METHOD AND APPARATUS FOR FLUID SEPARATION

Specification of the present invention relates to "method and apparatus for fluid separation".

The present invention relates to a method and apparatus for separation of multiphase fluid streams. The method and apparatus find application in particular in the separation of multiphase liquid streams, especially in separating liquid hydrocarbon water.

The method and apparatus are particularly suited for purifying water made subterranean well oil and gas.

Hydrocarbons produced from a subterranean well, such as oil and gas, are accompanied by amounts of other materials, including water. In some cases, the volume of water produced from the well may be significant. In many situations, the produced water is discarded to the re-injected in the terrain below, therein well from which it is produced or neighboring in a well. The requirements for the purity of water being in a manner such [...] are stringent. In particular, it is important that the solids content of the water is low and that the water contains a minimum amount of oil woodworm. Generally, it is required that the water contains less than 400 ppm [...] for oil and less than 2 ppm of sand. Further lower values are required in certain [...]. These requirements must be met so PFA prevent the well becomes plugged and legal requirements for suitability to [...] relating to water.

Conventional techniques to clean and purify the water produced from wells ready for [...] based on use of deposition tanks, in which the fluid stream is fed and mixed fraction a separation of lighter oil the water fraction denser occurs under gravity. The very small size of the oil droplets in the water requires stubborn residence time long deposition into a mixing vessel, such that a gravity separation whether actual. This, in turn, requires that the vessel volume is large. A large vessel such as this would be expensive to manufacture and install near the head downhole in a submerged location. Indeed, may not be possible to manufacture a vessel with sufficient strength to explosion or collapse for operation under pressures encountered in many [...][...] head well of deep water. Thus being, vessels are generally [...] deposition in the surface a fixed or floating platform.

This necessitates the provision of a manifold suitable for transferring water from the sea bed to the surface and return of the water to the sea bed ultrapurified for [...]. In addition, due to their size, deposition vessels occupy a large volume of space in the surface structure, which is very often space of much value. An additional problem is that the separation efficiency tanks deposition generally is low and only approaches acceptable levels after excessively long residence times for water in the tank. in turn, increases more the tank volume. Thereby, a need exists for a better system for purifying water produced to make it suitable for [...].

An alternative technique for oil removal D. the Eagle driven a [...] '23 d, often referred in the art as' [...]'.

These devices are advantageous in that they have a high separation efficiency, when compared with a gravity separation, by being compact and by a lack of moving parts. An array of hydrocyclone machinery is a set tied or in series. The first cyclone in the series is a cyclone oil - water volume (bow wow), wherein the concentration of oil feeding is reduced as much as 50% to 15% by volume. The water then is passed into a cyclone pre-[...] (CDP), wherein the concentration of oil is more reduced to around 0.2%. The final stage of separation cyclone is the [...]. There is a problem because the hydrocyclone machinery Han [...] effective as only the flow rates of liquid low. For example, a typical production is of the order of 1200 barrels of m 3) per day ([...]). However, it is required that the [...] assembly operates by a range much greater range of flow rates, up to coolant ([...]) (6359.49 m3/day). The known technology of hydrocyclone does not allow [...] cyclone operates by a wide range of flow rates and obtain such a consistently high separation efficiency.

Thereby, there is a need for a system that is improved separation able to attain a high separation efficiency for a wide range of flow rates of fluid. It also would be advantageous if the system was capable of being [...] head well in a underwater location, where the fluid leaving the well had the highest temperature and the lowest viscosity.

EP 1,352,679 shows a separator for separating a multiphase flow, the separator comprising an inlet for a fluid multiphase, a plurality of leaves, with at least one outlet being provided for each separate phase, and a annular main barrel bore. The separator operates to separation of components lighter and heavier by making the fluid from flowing in a rotating travel. While this separator is particularly effective in separating multi-phase fluid, such as gas, oil and water, it cannot ensure the high separation efficiency required in order to effectively purify water made sufficiently to allow [...]. In particular, sufficient oil droplets remain in the product water of this separator, to avoid water being [...] directly into a subterranean formation. Such PFA purify more water, it is necessary to provide a system that is low shear, such that droplets small remainders are not oil emulsified with the water fraction, since this emulsification making it a further separation very difficult, if not impossible, in a reasonable time.

The GB 2 2,374,028 shows a separator for oil and water mixtures employing a vortex separator for removal of the water volume of oil. The resulting oil/water is passed through a stack of plates inclined towards additional wiping of oil droplets of the water. The system of GB 2 2,374,028, although capable of separating water oil, is not able to provide a sufficient separation for water is re-injected in a subterranean formation.

Thereby, there is a need for improved separation technique to allow multiphase fluid streams are separated, in particular water and oil streams, so that water may be sufficiently clean oil allowing a [...] in a subterranean formation.

According to the present invention, is provided in a first aspect a method for separating a multiphase fluid stream comprising a component fluid heavier component and a lighter fluid, the method comprising causing the fluid to flow along a helical flow travel wherein the critical Reynolds number of the fluid stream is high, the fluid stream flowing at a Reynolds number below the critical high number, the fluid stream flowing at a rate sufficient to cause the fluid phases from separating.

The first aspect of the present invention employs the phenomenon of a fluid caused to flow in a conduit confined, as between two plates or the like, exhibit different flow regimes for the same fluid flowing in a conduit or tube open. In particular, the fluid flow forced exhibits a significantly increased critical Reynolds number, i.e., Reynolds number in which a turbulent flow begins. This, in turn, allows the speed of the fluid is significantly increased, while still maintaining a flow regime not turbulent. References to a "high critical Reynolds number" should be constructed such as.

By forming the helical flow travel so as to provide a high critical Reynolds number, the rotational speed of the fluid can be significantly increased, by leveraging the separation of the different phases. Preferably, the critical Reynolds number is greater than 10,000, more preferably greater than 100,000.

In a second aspect, the present invention provides a method for separating a multiphase fluid stream comprising a component fluid heavier component and a lighter fluid, method comprising cause fluid to flow along a helical flow travel extending around a central conduit, the fluid flowing at a rate sufficient to cause the component lighter fluid to move into the internal region of the helical flow travel; and collecting the lighter fluid component in central conduit.

Preferably, the method of this aspect utilizes the principle mentioned previously rising Reynolds number of the fluid stream. The critical Reynolds number of the fluid stream is high, while the fluid stream is maintained flowing at a Reynolds number below the critical high number.

In a further aspect, the present invention provides a method for separating a multiphase fluid stream comprising an fluid heavier component and a lighter fluid, the method comprising:

cause fluid to be forced along a first helical flow travel, travel the first flow having a first helical pitch, the first helical flow travel being sufficiently long to establish a fluid flow pattern established for the current rotating; cause fluid flow uniform rotating along a second helical flow travel, the second helical flow travel having a second pitch, wherein the second pitch is generally larger than the first pitch; and removal of fluid lighter of a radially inner region of the second helical flow travel.

method of the present invention is suitable for separating any fluid stream [...], including streams comprising one or more phases of liquid and gas phase or phases. The method is approximately suitable for separation multiphase liquid - liquid streams. An application of the method is the separation of crude oil of water produced from a subterranean well, before [...] water produced in a subterranean formation.

method is particularly suitable for the separation of a smaller fraction of a first fluid dispersed or continuous phase of the volume of a second fluid. Preferably, the fraction of lighter fluid is the dispersed phase.

In the first step of separation method, inlet fluid is divided into manageable portions allowing at an appropriate flow rate is achieved. The or each portion preferably is first made enter tangentially into a separator, thereby printing an if sufficient rotational speed upon the fluid to cause the phases begin to encompass. This separate roll, phases in current congregate and coalesce, thereby allowing the dispersed phase to form larger droplets.

The fluid stream is then made impeller rotate in a compact under pressure, so that the fluid is subjected to a high centrifugal force, allowing the fluid forms a rotating stable flow pattern. In order to prevent different fluid phases become further mixed, in particular emulsified, the fluid stream is established in a flow regime which is below the critical Reynolds number (i.e., Reynolds number above which the flow regime is turbulent). The critical Reynolds number will depend upon factors such as viscosity and specific weight of the fluid stream, the velocity of the fluid stream and dimensions of the conduit through which the current is passing. Preferably, the fluid is stabilized in a transient flow regime, thereby maintaining active if droplets of fluid phase dispersed. Herein, the impeller compact is arranged such that the Reynolds number can be significantly higher than the critical number custom, while still benefitting fluid in a laminar flow regime or transition. Such an effect generated, for example, when a fluid is made flow between two face plates, is known in the art. This effect is employed in the present invention, such a PFA allow high speed rotary fluid is obtained, while maintaining the fluid at a flow regime not turbulent. In this way, separation of the various phases due to centrifugal forces is improved.

The length of the first helical flow travel should be of sufficient length to allow fluid flow to be established centrifugally and stabilize in the flow regime required, more preferably a transient flow regime. The nature of the fluid stream, components thereof and the flow regime of the fluid being processed in the method will determine the length of the first helical flow travel. If required flow regime can be established quickly, the first helical flow travel will be correspondingly short.

Once a stabilized flow regime has been established, the fluid stream is made creep along a first helical flow travel. In this step, the fluid is acted upon by a centrifugal force to create a multiple gravity force, as a result of be caused to flow along the helical travel, their effect is cause fluid heavier is forced into the external cylindrical wall and the fraction lighter or fractions migrates to the inner region of the impeller. The helical flow travel has a first pitch. It is preferable that the pitch of the helical flow travel remains constant throughout the length of the first helical flow - [...], as the stream of fluid is being pressurized through plates helix.

After this, the fluid stream is brought to a second helical flow travel. The second helical flow travel has a second pitch, which is larger than the first pitch helical flow travel. The second pitch may be constant throughout the length of second helical flow travel. However, in order to reduce frictional losses in the fluid stream as a result of back pressure, is preferred that the cross-sectional area of the second helical flow travel increases along its length. This is achieved, more conveniently, by having the pitch of the second helical flow increased travel along its length. The pitch may increase in increments or gradually. In a preferred embodiment, the pitch of the second helical flow travel increases continuously along the length of second helical flow travel. In a preferred arrangement, the pitch increases by up to 5% for each travel about the fluid flow around the axis of the travel [...] flow, more preferably up to 3%, especially around 1% for each back. Thus, a flow regime is maintained, allowing the lighter fractions fluid migrates to the interior region of the helical flow travel, from where they are removed.

The second helical flow travel should be long enough to allow the phases of lighter fluid being collected and removed from the fluid stream. Small droplets of the lighter fluid may remain in the fluid phase heavier. If so, and the desired level of purity required or fluid has not been obtained, additional processing stages can be employed, as follows.

If a further separation and purification are required, the method may comprise additional steps, in which the rotational speed of the fluid stream is increased so PFA generate a vortex central fractions of lighter fluid, from the fluid light may be retrieved. The increase in speed of rotation may be accomplished using a third helical flow travel, along which the cross-sectional area of the flow travel is adjusted, so as to cause an increase in fluid speed required for the generation of vortex. In a preferred arrangement, the pitch of the third helical flow travel increases in the direction of flow. The increase in pitch can be continuous or in increments. Preferably, the third step in the helical flow travel increases along its length substantially entire. Such PFA generate the required increase in fluid velocity, the helical flow travel narrows in width in the radial direction, as the pitch increase. The increase in velocity of fluid is preferably controlled such that the critical Reynolds number of the fluid flow is not exceeded. The cross-sectional area of the third helical flow travel is such that excessive frictional losses and back are avoided.

After the increase in rotational speed, the fluid is ejected from the third helical flow travel in the form of a wall annular space rotating fluid, which contains a rotating core fluid.

In the core rotating fluid, a vortex separation is established. At this stage, the lighter fluid remaining is made migrate toward and to the vortex, with the fluid circulating in the annular region heavier extending around the vortex established. At this point, a helical flow travel need not be provided and flow regimes of the aforementioned the vortex can be established within a conduit open, such as a tube or a pipe. Thus, the vortex is established when exiting the second helical flow travel.

In many cases, the vortex induced in this way is relatively short, as compared to the length of the surrounding conduit. In such cases a vortex short, the stability of the vortex can be reduced, leaving the vortex susceptible to changes in the flow rate of the fluid smaller. Thereby, providing a medium is preferred to establish the vortex. In a preferred embodiment, the vortex is formed below a conduit for removal of fluid lighter that migrated into and has collected in the vortex. A preferred means for capturing and establishment of vortex is a cone of guide is a guide conduit of suitable dimensions disposed within said conduit region of its opening to the vortex. Thus, the vortex is established within the inlet region in the fluid conduit and volume.

The fluid stream leaving the separation region will contain little or no vortex component lighter and will comprise mainly on heavier fluid components. If some lighter components remain, additional steps of separation may be performed, as follows.

In a preferred embodiment of the present invention, the method further comprises introducing the fluid stream into a fluid deposition - fluid, in which the components of lighter fluid components are separated from heavier fluid under gravity. The speed of the fluid stream in the deposition region of fluid - fluid is significantly lower than in the previous separation areas or zones. In particular, the speed is such that the Reynolds number of the fluid stream is well below the critical Reynolds number, more preferably in the laminar flow regime.

Preferably, the fluid stream is made rotate in the deposition region of fluid - fluid. This is achieved, more advantageously, by having rotation printed to the fluid stream when the outlet region vortex separation. Although the effect of major separation in this region is a gravity separation, the rotating flow regime will cause components of lighter fluid to concentrate in the central zone or innermost region, allowing easier removal and a separation [...].

To aid in separating any remaining lighter fluid components, the method preferably comprises the centering of rotating flow of the fluid stream within the deposition region of fluid - fluid. This is achieved preferably in such a way that the cross-sectional area of the fluid flow in travel deposition region of fluid - fluid is reduced in the direction of flow.

In a preferred arrangement, a fluid richer component lighter fluid is removed from the central region lower deposition region of fluid - fluid is passed to central region region upper fluid deposition - fluid. To avoid a remixing in centrifuging outlet region, a hood may be provided axially to allow the lighter fluid droplets to move to the region of lighter fluid not disturbed by rotating phase volume. Thus, the separation of the heavier and lighter components is improved. In particular, the lighter components are moved to the upper portion of the deposition region, which already is relatively rich in lighter components, with heavier components thereby transported back to the lower portion under the effects of gravity.

Windows and monitoring lines, fluid sampling and fluid injection can be provided, which terminate in appropriate [...] within the system. For example, may be provided with lines for injecting pressurized gas or a liquid fluidized with a gas to cause upward movement of bubbles to ascend through the heavier fluid phase. This would effect separation predominantly by gravity. In particular, lightweight phases, such as oil and other hydrocarbons may adhere to the surface of gas bubbles and, then, be moved at a faster rate for regions of lighter fluid, as is satisfying - mind employed in flotation separation processes.

If desired, separation of the fluid component lighter components heavier fluid can be enhanced by adding additives active in inducing coalescence component lighter fluid. Suitable additives are well known in the art and eating - officially available. Scale inhibitors can be applied, to avoid the formation of scale, in particular in [...] wherein huh significant a pressure loss into the fluid stream, such as at the inlet to the system of the present invention. [...] can be added upstream of the first stage of separation, so PFA improve the separation fluid phases. Corrosion inhibitors may be required in the system of the present invention, in particular downstream sets [...] separation. [...] can be introduced, as required in the system, so as to promote aggregation of fluid phases.

Wax inhibitors may be required, when oil is present as a fluid phases, so prevent crystallization of PFA wax compounds of high molecular weight at regions of high oil concentration.

Other additives which may be employed include reducing friction, hydrate inhibitors and biocides.

The remaining fluid in the process will be almost entire population - [...] on the component or components heavier. These preferably are passed to a region of fluid removal, in which a fluid stream consisting essentially of the heavier fluid component is removed. The fluid stream preferably is made rotate in the fluid removal zone, nonaqueous fluid stream being removed from the central region of the zone of fluid removal. Thus, any heavy components, such as a sediment or the like, may be collected under gravity is withdrawn from the system, for example, on a type of batch, as sufficient sediment to collect in an appropriate receptacle.

A particular advantage of the method of the present invention is that it can be applied at a modular primer. Thus, a wide range of flow rates of operating fluid can be accommodated, and provided a separation process, which can be applied for extended time periods with significant variations in the production fluid. This is of advantage in particular in applying the method for separating [...] in remote, especially in operations head well submerged.

Thereby, the present invention also provides a method for separating a multiphase fluid stream comprising a component fluid heavier component and a lighter fluid, the flow rate in volume of the multiphase fluid stream undergoing a variation over time, the method comprising the provision of a plurality of sets of separation for performing the method steps of:

allow a current flow rate controlled between a set of dedicated separation; establish a fluid flow pattern for the current stabilized rotating; cause fluid to be forced rotating established along a first helical flow travel, travel the first flow having a first helical pitch; cause fluid flow uniform rotating along a second helical flow travel, the second helical flow travel having a second pitch, the second pitch where is greater than the first pitch; and remove fluid lighter of a radially inner region of the second helical flow travel; sets are [...] to accommodate different fluid flow rates; and select one or more sets of separation for performing the method steps according to the flow rate in volume of the multiphase fluid stream.

The method steps performed on each separation assembly can have any of the preferred features described herein above or specific.

In one embodiment, the separation method further comprises modulating the provision of a finishing assembly for performing the steps of depositing fluid - fluid described herein above, wherein each of the plurality of separation is connected at its output to the set of finishing.

In addition to the foregoing method aspects of the present invention, are also provided corresponding aspects of apparatus. Thus, in a first aspect, the present invention provides an apparatus for separating a multiphase fluid stream comprising a component of. fluid heavier component and a lighter fluid, the apparatus comprising a helical flow travel having a cartridge inlet " fluid, a first outlet for a fluid heavier and a second outlet for a lighter fluid, the helical flow travel being formed such that the critical Reynolds number of the fluid stream flowing along the helical flow travel to be elevated.

Preferably, the second outlet component to the lighter fluid is disposed axially centrally in the helical travel, in particular opening up to a fluid conduit lighter axially center.

The helical flow travel may be arranged to provide the critical Reynolds number raised described herein above. In particular, this can be achieved by adjusting the inner dimensions of the helical flow travel according to the properties of the fluid stream to be processed.

In a further aspect, the present invention provides an apparatus for separating a fluid stream comprising a component fluid heavier component and a lighter fluid, the apparatus comprising:

a means for selecting a predetermined flow rate of fluid stream; a first conduit for establishing a fluid flow pattern for the stabilized rotating fluid stream having a first helical flow travel, travel the first flow having a first helical pitch; a second conduit having second helical flow travel, the second helical flow travel having a second pitch, wherein the second pitch is greater than the first pitch; and a means for withdrawing the fluid lighter of a radially inner region of the second helical flow travel.

apparatus comprises a first conduit having a helical passage through therefrom, through which a fluid may be made flow in a helical flow travel. In order to prevent the different fluid phases are more mixed, in particular emulsified, first conduit preferably is shaped so that the fluid stream is stabilized in a flow regime that is below the critical Reynolds number (i.e., Reynolds number above which the flow regime is turbulent). The critical Reynolds number will depend upon factors such as viscosity and specific weight of the fluid stream, the fluid stream velocity and the dimensions of the conduit through which the current is passing. Thereby, the specific shape, the dimensions and length of the first conduit will be determined by the properties of the feed stream being processed. Preferably, the conduit is of such a size that the fluid be stabilized into a transient flow regime, thereby maintaining if droplets of fluid phase dispersed active. An array is particularly preferred that the first conduit comprises a tube having an impeller inner regulate, in order to provide the helical flow travel.

length of the first helical flow travel within the first conduit should be sufficient to allow the flow of fluid to stabilize in flow regime required, more preferably a transient flow regime. The nature of the fluid stream, components thereof and the flow regime of the fluid being processed in the method will determine the with - the first flow travel [...] helical. The first helical flow travel is long enough to allow time for the centrifugal separation of the fluid phase lighter phase in volume of fluid heavier. If the flow regime required can be established quickly, the first helical flow travel will be correspondingly short.

Preferably, the pitch of the first helical flow travel remains constant throughout its length.

apparatus preferably is provided with a feed conduit, wherein the multiphase fluid stream is forced to be separated, before entering the first conduit. The apparatus preferably comprises a means for establishing a flow of fluid in the conduit rotating power. Preferably, the conduit feeding comprises a tangential opening through which the feed stream is forced, the tangential arrangement of the opening causing the fluid rotate, as it run along the feed conduit and is subjected to high centrifugal forces providing a region of initial phase separation, before the fluid enters the first conduit.

apparatus further comprises a second conduit, in which a separation of the different phases of the fluid stream occurs. The second conduit also comprises a helical flow travel extending therein. In a preferred arrangement, the second conduit comprises a tube having an impeller extending [...] therein to the provision of a second helical flow travel. Preferably, the pitch of the second helical flow travel increases in the direction of flow along the second flow travel. The increase in pitch can be in a manner or continuous increments. In a preferred arrangement, the pitch of the second helical flow travel is increased over the entire travel of the second length substantially helical flow within the conduit.

pitch can increase up to 5% for each travel about the second helical flow around the axis of the helical flow [...] travel, preferably up to 3%, more preferably around for each back.

For separating the phase fluid lighter phases heavier fluid, means for removal of the fluid phase lighter is provided within the second conduit. Preferably, the means for removal of fluid lighter comprises a collection conduit extending coaxially within the second conduit, the impeller extending within annular space around the collection conduit.

The feed conduit, the first and second conduits may comprise separate components of the apparatus. However, in a more convenient arrangement, the feed conduit, the first and second conduits are adjacent portions of a single tube, a first impeller being provided in an upstream portion of the tube to the provision of the first helical flow travel, and a second impeller being provided in a downstream portion of the tube to the provision of the second helical flow travel. In such an array, the means for removal of fluid lighter may comprise a collection conduit extending coaxially within the single tube, the collection conduit with openings in the portion that extends into the downstream portion or second portion for collecting fluid.

In many circumstances, the provision of the apparatus with the first and second conduits, optionally with a feed conduit, will result in a centrifugal separation phases acceptable fluid lighter and heavier. However, if a further separation is required, apparatus may comprise one or more of the following components.

If a further separation is required or desired, preferred technique is the use of vortex separation action, which subjects the remaining flow to very high centrifugal forces. Thus being, in such a case, the apparatus further may comprise a conduit for retention of a vortex, said conduit being arranged to receive a fluid leaving the second helical flow travel. In order to provide the optimum vortex for separating fluid - fluid, the rotational speed of the fluid stream should be adequately high. Thus being, if required, the apparatus further may comprise a means for increasing the speed of rotation of fluid disposed between the outlet of the second helical flow travel and the inlet to the conduit retention of a vortex.

A medium suitable for increasing the rotational speed of the fluid is a third helical flow travel. In order to provide the necessary increase of Veloc - ness, the cross-sectional area of the third helical flow travel decreases along the length of the helical flow travel.

The increase in cross-sectional area may occur in a continuous manner or in increments. Preferably, the decrease in cross-sectional area occurs over the entire length substantially - [...] travel have helical flow. The third helical flow travel more conveniently is formed within a downstream portion of the pipe containing the first and second helical flow paths.

Can be permitted the vortex is formed inside a conduit substantially empty, such as a downstream portion's hollow conduit containing the first, second and, if present, third helical flow paths. In some process regimens, it may be necessary to provide a means to establish the vortex. In a preferred arrangement, the apparatus further comprises a conduit for collecting component lighter fluid from the vortex, the means for establishing vortex being the pro - living by a tapered portion in the region of the opening of the said conduit.

The apparatus described herein above may be conveniently housed inside a single conduit or tube, as already mentioned. A further separation may be provided by means of a separation process essentially by gravity. Thereby, the apparatus further may comprise a vessel for receiving the fluid stream, the vessel having a volume sufficient for reducing the Reynolds number of the flow of fluid stream, such that a fluid inlet in the vessel may be subjected to a gravity separation. In such an array, single tube or conduit, as described herein above, conveniently may extend into the vessel. In a preferred arrangement, the apparatus may be modular design, as described herein below, wherein a plurality of such conduits can extend in a single vessel.

To assist in the process of gravity separation into the vessel, the apparatus may whip flow comprising a means for inducing a rotating flow in the fluid stream entering the vessel.

will allow a gravity separation efficient and will prevent a contaminating - tion crossflow of the separate phases. This means more preferably is a tangential outlet in the conduit through which the fluid stream is introduced into the vessel. To assist in separating, the vessel may comprise a means for centering the rotating flow of fluid into the vessel, e.g., an inverted cone [...] coaxially into the vessel. The inverted cone can be provided with a flow guide extending helically along its outer surface in the direction of fluid flow.

[...] removal components lighter fluid phases into the vessel heavier, the apparatus further may comprise a conduit which extends coaxially within the vessel, the conduit having [...] - frogs therein through which components of lighter fluid may leave the fluid stream. In a preferred arrangement, the conduit having an outlet for the components of lighter fluid into the vessel, the outlet being disposed upstream of the inlet fluid stream.

The fluid remaining in the vessel will be essentially heavier fluid components. The apparatus further may comprise a fluid collection zone heavier, a conduit fluid collection weighed being disposed centrally within the collection zone, the conduit having a plurality of apertures therein for collection of the heavier fluid.

If the feed stream of fluid comprises any solid components, remains at this apparatus, traveling in a downstream direction. In such cases, the apparatus further may comprise a solids collection zone and a means for removal of solids of the collection zone, means removing solids on a continuous or intermittent.

As mentioned above, the apparatus is particularly suited to be constructed in a modular. In particular, the assembly comprising the first and second conduits and, if present, the conduit for housing a vortex of fluid and [...] means provided for increasing the rotational speed of the fluid stream may be housed in a single conduit, representing a single separation module assembly. Thereby, in a further aspect, the present invention provides an apparatus for separating a multiphase fluid stream comprising an fluid heavier component and a lighter fluid, the flow rate in volume of the multiphase fluid stream undergoing a variation over time, the apparatus comprising a plurality of sets of separation, as described herein above, and operable to accommodate different fluid flow rates; the apparatus further comprising a means for selectively operating one or more sets of separation according to the flow rate in volume of the multiphase fluid stream.

The apparatus can be operated with a module, a selection of modules or with all sets of separation being in use. Thus, individual separation assemblies may be placed in line and taken out of line, as the volumetric flow rate of the stream vary. This is particularly effective when the individual separation assemblies are sized to accommodate different fluid flow rates. Preferably, the apparatus comprises a means for feeding a fluid flush for each set of separation, so as to allow each set of separation is flushed and cleaned, before being placed in line is taken out of line.

If a stage of gravity separation is required, the modular assembly may comprise, further, a separation vessel, as described herein above, each of the set of separation extending into the vessel separation.

In a use of the modular apparatus of the present invention, a plurality of modular separation units may be provided, each comprising a plurality of sets of separation of varying sizes. A group of such units can be grouped around a head location downhole in a field or oil, for example, at one location or underwater surface, so as to serve a group of wells.

The separation system of the present invention helical presents a problem in particular when arriving at start-up and stop, if the conduits for the lighter fluid produced in the process are not to be contaminated with heavier fluid components. This problem is solved by the methods start and stop forming additional aspects of the present invention.

Thereby, the present invention provides a method for start-up of a separation system for operating helical separating a multiphase fluid stream comprising an fluid heavier component and a lighter fluid, the method comprising feeding the separation system helical with a first fluid stream consisting essentially of the component higher fluid J. weighed; when velocity of fluid inside the system separation helical has reached the minimum operating speed the fluid stream multiphase, the substitution for a period of time of the first fluid stream by multiphase fluid stream to be separated.

A method for stop separation system helical from a normal operation, in which a multiphase fluid stream comprising a component fluid heavier component and a lighter fluid is being fed to the separation system helical, comprises the steps of introducing a first fluid stream consisting essentially of the heavier fluid component in powering multiphase fluid stream over time for replacement of the multiphase fluid stream; when feeding fluid is in first fluid stream, reducing the flow rate of fluid feed to zero.

separation system preferably is left filled with helical first fluid, after the flow rate of feed fluid has been reduced to zero. Thus, the starting method mentioned above may be employed, without delay and optimally to achieve normal operating conditions with minimal contamination of the lighter fluid streams.

procedures start and stop of the present invention are of advantage in particular when the separation system is disposed in the helical modular shaped discussed herein above is operated [...] a selection varied separation modules to accommodate helical fluid flow rates and different compositions.

Embodiments of the present invention will be described, now, by way of example only, with reference to the associated drawings, in which:

figure 1 is a cross-sectional view of a complete separation according to an embodiment of the present invention; Figure 2 is a cross-sectional view of the upper portion of Figure 1 separation; Figure 3 is a plan view of the separation apparatus of Figure 1; Figure 4 is a stylized cross-sectional view of a helical separation according to the present invention; Figures 5 to 5c are a cross-sectional view in a stylized scaled up three portions of helical separation regions labeled as the, b and c in Figure 4; Figure 6 is a cross-sectional view of a set of separation [...] helical of the present invention; Figure 7 is a cross-sectional view of the portion of the assembly of [...] Figure 1 along the line of the vile it vile; Figure 8 is a cross-sectional view of the portion of the assembly of [...] Figure 1 the along line VIII have it VIII.; Figure 9 is a cross-sectional view of the upper portion of Figure 1 the separation along an axis different from that of Figure 2; Figure 10 is a schematic representation of a system of the present invention, indicating how the monitor tubes is employed for monitoring various regions of the system performance; Figure 11 is a histogram showing bands performing flow and the operating pressure ranges of operation for sets of different dimensions; and Figure 12 is a graph indicating the selection of different combinations of assembly to accommodate different flow rates of feed stream.

Referring to Figure 1, there is shown an array of separation, generally denoted as 2. the assembly is shown disposed substantially vertically on the bed of the sea, with the lower portion of the assembly extending below the sea bed. This is a convenient arrangement for location of the assembly, in particular adjacent to a head assembly downhole submerged." Thus, head assemblies can be found in existing well the separation assembly of the present invention, significant installation without modification head well.

The assembly 2 is separation formed around a generally cylindrical tubular housing 4. the housing 4 most conveniently is a section of conductor commercially available. The conductor is supplied in a range of sizes, including the nominal sizes of 108 cm (42 inches), 92 cm (36 inches), 76 cm (30 inches) and 50 cm (20 inches). The housing 4 may be constructed from a section of the conductor, with the diameter being selected to the accommodation of the volumetric flow rate of the fluid stream to be processed. The embodiments shown in Figures and described herein are associated forward [...] with separation of fluid in a submerged location. However, the method and apparatus with only minor modifications can also be applied to surface-bound conductors or leads platform.

The separation assembly 2 comprises a plurality of discrete components. A set of inlet and outlet 6 is connected to the upper end of the housing 4, supply fluid to the assembly for separation and whereby the separate fluid streams are removed. The assembly still clinging 2 comprises a plurality of sets of helical separation 8 extending within the housing 4, wherein the first stage of separation of fluid components lightweight components heavier fluid is performed. The remaining portion of the housing 4 is arranged to provide other stages of prediction error section, comprising a stabilization region fluid 10, a second stage of fluid separation 12 - fluid, and one stage of separation and recovery fluid - solid end 14. each of these components will be discussed in more detail below.

A fluid interface/slight operating heavier fluid 16, 17 maximum a high level and a low level minimum 18 for the fluid within the housing 4 are represented in Figure 1, and are shown as being along the length of helical separation assemblies 8, so that they all lie above the lower end or downstream impeller assemblies.

Referring to Figure 2, the inlet assembly and outlet 6 is mounted on the upper end of the housing 4 via a connector of conventional design. The inlet assembly and outlet 6 comprises a body of generally cylindrical inlet 22. a buffer assembly 24 is mounted on the upper end of the body 22 and inlet comprises a stopper bottom 26 and a plug top 28, which in conjunction define a separation zone of [...] 30, wherein a gas is removed from the liquid present in the zone 30. A venting gas is provided by a hole 32 extending obliquely through the upper buffer 28, which is in turn connected to a conduit 34 gas recovery by flange of conventional arrangement. A hole 35 is formed in the side lower buffer 26 and mates with a fluid conduit 37. a hole axially center 36 extends through the body inlet 22, connecting the internal region of the housing 4 with a chuck of fluid 38 extending through the separation zone gas - liquid, which, in turn, connects with a hole extending laterally 40 way the upper buffer 28. A liquid can be removed through this array, to be taken the liquid conduit 42, which is connected to a suitable line ([...]) via a conventional flange assembly. A hole 44 coaxially extends through the upper buffer 28 and provides an opening for the removal of solid material, such as a slit from the assembly, chemical injection, or for monitoring purposes. A valve 46 is shown connected to the bore 44 in Figure 2 coax.

Turning on again to the inlet body 22, a plurality of liquid conduits in the form of holes is provided [...] 48 spaced around the center hole 36. Conduits liquid originate a direct connection between the separation zone gas - liquid 30 and the upper region interior of the housing 4, through which fluids can pass, as required.

The LOC ' powder inlet 22 is provided with an additional set of holes 50 [...] spaced around and radially outward from the center hole and bores [...] 48. As will become apparent, the bolt holes originate the feed conduit for each set of helical separation 8. each of the bores 50 is connected at its [...] lower opening to a respective helical separation assembly 8, whose details are provided herein below. The layout of the holes 50 and their assemblies [...] separation is shown in 8 helical [...] planar view in Figure 3. as shown in Figure 3, each of the bores is provided with an inlet [...] disposed tangentially 52, from which radially extends a hole 54. An inlet conduit 56 is connected to the end of each bore 54 radially via a conventional flange assembly. Each inlet conduit 56 is connected to a collector fluid inlet 58, shown in Figure 3 as a circular tube extends around the upper portion of the assembly. A conduit feed fluid connects to collector fluid inlet 58, whereby a multiphase fluid stream can be fed to be processed. The flow of fluid from the collector fluid inlet 58 for each inlet conduit 56 is controlled by a valve 62. as shown in Figure 3, each inlet conduit 56 is provided with its own valve 62 and a one way check valve 63, to prevent any return flow occurs. This provides independent control of each inlet conduit 56 and fluid flow for each set of helical separation 8.

Thus, the assembly is operable for the accommodation of larger variations in flow rate and composition of the feed stream of fluid. It will be appreciated that alternative arrangements are possible, wherein a single valve is used to control fluid flow to two or more sets of helical separation 8, although with a reduction in freedom of operation.

Such an array can be employed, for example, in situations where only limited variation in the flow rate and/or composition of the feed stream of fluid are envisioned during the life in the installation work.

Radial windows extend through the inlet body 22 and connect with respective lines 53, which extend to a proper position within the housing 4. they are employed for fluid injection operations, fluid sampling or monitor process.

A purging system fluid is also shown in Figure 3 and comprises an array similar to fluid inlet system described above, including a fluid manifold 64 having a flush round flush inlet conduit 66 which extends into each inlet conduit 56. The operation of the purging system fluid is to the provision of a stream of flush fluid, typically water, for each set of helical separation, as it come into line or out of line. A valve 68 is positioned in each inlet conduit 66 flush, so as to provide independent control purging of each helical separation 8.

Again, two or more sets of helical separation 8 may have its purging controlled by a single valve. A fluid feed conduit 70 supplies the purge fluid flush to flush the fluid manifold 64.

Although referring to Figure 3, it is convenient to note the layout of the sets of helical separation 8. as shown, the assembly comprises a total of 10 sets of helical 8 separation of a range of sizes, capable of accommodate a range of flow rates different fluid. In the layout shown, the assembly comprises each of the set of separation 8 having helical a nominal diameter of 10 cm (4 inches), 12.5 cm (5 inches) and 15.25 cm (6 inches). In addition, the assembly comprises 7 sets of helical separation having a nominal diameter of 8 7 inches (18 crude). The arrangement shown thus can operate for a wide range of flow rates of feed fluid, from the lower flow rate when the set of helical separation 10.16 cm (4 inches) single is in line, to a maximum flow rate when all sets of helical separation are operating. Combinations helical separation assemblies can be made to 8 accommodating flow rates there between.

The arrangement shown in Figures 1 3 is one in which collectors feeding and flush and their respective valves are integral with the inlet assembly and outlet 6. it will be appreciated that alternative arrangement may be employed, wherein valves and collectors are combined in a separate module which is connected to inlet and outlet lines 6 by suitable. Thus, valves and its control may be more readily accessible to recovery and replacement.

It is a significant advantage of the assembly that the number and size of helical separation assemblies disposed within the housing may be varied to accommodate a load in particular, allowing the design and construction of the assembly are generally on a largely modulate. This in turn allows for design, construction, maintenance and repair are direct and economical.

The construction and operation of separation assemblies 8 will be described helical rotates, with as reference Figure 4, which is a stylized representation of a typical set. It will be appreciated that the assembly shown in Figure 4 is significantly shortened, for ease of reference, the relationship of the overall length to the diameter of the impeller assembly typically being much greater than that depicted in Figure 4.

Referring to Figure 4, a set of helical separation 8 comprises a conduit 100 is generally cylindrical, shown in Figure 4, to extend vertically downward from the body inlet 22.

A fluid conduit light 102 in the form of a generally cylindrical tube extending coaxially in the cylindrical conduit is open at its uppermost end separation zone gas - liquid 30 in the buffer 24. A ring cavity is formed around the fluid conduit 102 between the light fluid conduit 102 and the slight cylindrical conduit 100. The uppermost region 104 the annular cavity is empty, allowing the free passage of fluid. A radial bores 54 in the body inlet 22 terminates in an aperture 52 in tangential region uppermost cylindrical conduit 104 to the annular cavity region adjacent and below the uppermost region 104 is a stabilization region fluid flow indicated as in Figure 4. in this region, an impeller 108 is disposed within the annular cavity and extends around the fluid conduit light 102 for forming a helical flow travel for fluid movement within the cylindrical conduit. The function of this region is allow fluid stabilizes in the flow regime required, forcing the fluid to flow in a helical travel compact. The propeller flow stabilization region 106 is formed to the provision of a fluid flow pattern and stable to allow the phases partition centrifugally and break, undergoing multiple rotary forces of gravity and before exiting. In the layout shown in Figure 4, the cross-sectional area of the helical flow travel preferably is constant along the entire length of impeller 108. As the impeller 108 is disposed within a cylindrical conduit 100, this dictates that the pitch of the impeller 108 preferably is constant along the length of the region 106. In other arrangements, the pitch of the impeller 108 may be varied along its length, such PFA provide the flow pattern required at its outlet end.

The movement of droplets of the fluid phase specific gravity stabilization region helical fluid flow 106 is depicted in Figures 5 to 5c.

The end of the stabilization region flow impeller 106 and 108 is contiguous with a region of fluid separation, generally indicated as 110. In this region, an impeller 112 is disposed within the annular cavity and extends around the fluid conduit 102 light, for forming a helical flow travel for a fluid moving within the cylindrical conduit. The function of this region is separating the fluid phase lighter phase fluid more heavily. The fluid conduit 102 is provided with light a plurality of windows or holes 114. The windows 114 are formed in the upper region of the travel inner helical flow. The light liquid phase is recovered through windows 114 in fluid conduit 102, as described herein below.

PFA provide such phase separation of fluid in the region of fluid separation 110, the cross-sectional area of the helical flow is increased travel along the length of the region 110. Such PFA provide this increase, the impeller 112 is shown in Figure 4 as increasing pitch along the length of the region of fluid separation 110. The increase is shown as being an increase of around 1% in step impeller 112 for each full round around the fluid conduit light 102. The increase in pitch is to allow a natural flow of the fluid (as opposed to the flow forced in helical sections upstream) and to prevent back pressure fluid arises due to frictional forces within the helical channel. If allowed to occur, the fluid back pressure would rise to a transverse flow detrimental force into the fluid. The increase in pitch will depend on the properties of the fluid being processed and is selected to allow the natural motion of the phases for the lighter fluid conduit occurs, while allowing the remaining heavier fluid phases continue along the flow travel [...] end region of fluid separation 110 and impeller 112 is contiguous with an enhancement region fluid speed, generally indicated as 116. In this region, an impeller 118 is further disposed within the annular cavity and extends around the fluid conduit 102 light, for forming a helical flow travel for a fluid moving within the cylindrical conduit. The impeller 118 terminates at the open end of the fluid conduit light 102. The function of this region is to increase the speed of the fluid remaining in the cylindrical conduit 100, so as to provide a stable vortex in the region downstream or lower conduit 100, as described below.

In the region enhancement fluid speed 116, the impeller 118 is shown in Figure 4 for each footfall [...] back around the fluid conduit light 102. The increase in pitch will be determined by the nature of the fluids being separated and by charging [...] separation to be performed. A rate of increase of typical pitch of the helix is around 3% for each back around the fluid conduit light 102. The portion of the fluid conduit light 102 that extends through the region 116 typically is cylindrical and of substantially constant diameter. An alternative embodiment is to provide a fluid conduit 102 slight tapered portion or widened, so that their diameter increases through this region in the direction of flow of fluid in the annular cavity. This in turn causes the ring cavity between the fluid conduit and the conduit 102 light either cylindrical cross-sectional area in the downstream direction of fluid flow in the annular cavity.

A cross-sectional view of a typical entire helical separation assembly 8 is shown in Figure 6, from which it will be appreciated that many separation operations require the length of three regions 106, 110 and 116 is many times larger than the diameter of the cylindrical conduit 102. It will also be noted that the helixes 108, 112 and 118 are shown as a single helical element extending within the cylindrical conduit 102. This arrangement is preferred. However, it will be appreciated that each of the helices 108, 112 and 118 may be disposed separately within its own cylindrical conduit portion 102, or even within separate conduits. The arrangement shown in Figures 4 and 6 is advantageous upon applying the separation assembly 8 in a modular helical, as described. For certain fluid separations, arrays can be employed double-helix, comprising two helix paths between the conduits 100 and 102.

As cited above, the impeller 118 within the region enhancement fluid speed 116 terminates at the end of fluid conduit light 102. The cylindrical conduit 100 is provided with an outlet oriented and angled 120 on its lower end downstream, whose details are described herein below. The downstream portion of cylindrical conduit 100 extending from the end of the fluid conduit 102 tay the outlet 120 light conduit 100 is a cylindrical volume substantially empty and gives a vortex region generally indicated as 122. As will be described below, a vortex is established in this region extending in the direction to downstream from the end of the fluid conduit light 102. For acquisition of the vortex created, a vortex guide, in the form of an inverted cone 124 and a vortex tube 126 are disposed within the end portion of the fluid conduit light 102, as shown more clearly in Figure 6.

The assembly shown in Figures 4 helical separation and 6 may be operated as a separation system independent. Alternatively, if a further separation, such as a [...], is required, the separation may be helical assembly used in conjunction with systems additional error prediction section and the method described below, more suitably in an array as shown in Figures associated.

Referring to Figure 7, there is shown a cross-sectional view of the portion of the embodiment of the present invention immediately downstream from the outlet 120 of helical separation 8.

As shown in Figure 7, a plurality of sets of helical separation 8 (two of which are visible in Figure 7) extends downwardly into the housing 4 and is retained in position by a guide assembly of deflector plate 123. A plurality of sets of guide may be provided deflector plate 123, depending on the length of the sets of helical 8 and separation of their relative dimensions. Deflector plate assemblies 123 originate guide and spacing for helical separation assemblies. In addition, they serve for dispersion of any large gas bubbles that may be present in fluid volume, as a result of a flotation gas be employed.

The outlet 120 of each helical separation 8 is oriented to direct a fluid leaving the conduit in a tangential direction downwardly, so PFA create a large vortex flow regime, as described below. A fluid conduit 160 secondary light in the form of a generally cylindrical tube coaxially extends within the housing 4 and has its open upper end in the form of an outlet 162. It will be appreciated that the outlet 162 is atop, the outlet 120 at the lower end of each helical flow separation 8. rotating below outlets initially will consist transverse streams, even have stabilized. The fluid conduit as a light 160 your hood to help any fluid droplets PFA slight move upward through this flow region not stabilized a fluid conduit 164 weighed coaxially extends within the secondary fluid conduit light 160 upwardly and coaxially through the mandrel fluid 38, which is connected on its upper end to the liquid conduit 42, as shown in Figure 2.

A solid/injection conduit 166 extends coaxially within the fluid conduit 164 and weighed is connected at its upper end wellbore coax 44 in buffer upper 28, as shown in Figure 2. material flow through conduit 166/solid injection is controlled by the valve 46, also shown in Figure 2.

An inverted cone 170 is disposed around the fluid conduit and spaced secondary light 160 ends lower separation assemblies 8. helical helical 172 a palette is provided in the tapered surface of the inverted cone 170. The region within the housing 4 between the lower ends of helical separation assemblies 8 and the downstream end or lower inverted cone 170 is a region of [...] fluid flow, generally indicated as 10 in Figures, whose purpose is to establish a flow pattern of rotating slower fluid flowing down in this region from outlets of 120 sets the inverted cone 8. helical separation 170 is of a length and an angle such to the provision of a sufficient reduction in travel between the annular flow housing 4 and the secondary fluid conduit light 160, for creating an annular rotary speed higher fluid for carrying out one final separation phases fluid lighter and heavier in the next region of the assembly.

The region of the housing 4 immediately downstream or below the inverted cone 170 is a second stage of fluid separation - fluid, generally indicated as 12 in Figures. In this region, phases of lighter fluid remaining is finally removed from the assembly. To achieve this, the fluid conduit 160 is provided secondary light with a plurality of windows or holes 174 the along its length from within the inverted cone 170, whereby the lighter fluid phases may enter the conduit 160 and travel along the annular cavity between the fluid conduit and the light 160 fluid conduit 164 weighed. It will be appreciated that the fluid conduit is closed secondary light 160 on its lower end 161, as shown in Figure 8.

Referring to Figure 8, there is shown a cross-sectional view of the downstream portion or lower separation assembly. The final assembly region is the stage separation and recovery fluid - solid end, generally denoted as 14 in Figures. A palette conical 176 is disposed at the downstream end of the second stage of fluid separation - 12 and provides a fluid barrier to the lighter fluids in the s - skip annular central and ensures that only components of fluid heavier solids in the outer annular space and continue in the direction of flow to downstream. The finger conical 176 marks the upstream end of the stage of separation and recovery fluid - solid end 14. The portion of the fluid conduit 164 extending heavy for this end region 14 is perforated by a plurality of windows 180, through which the fluid phases heavier are withdrawn.

The solid/injection conduit 166 extends to the end region of the fluid conduit 164 weighed, as shown in Figure 8. means may be provided for withdrawal of solid material, such as silt and sediment, through conduit 166/solid injection, e.g., by a reduced pressure or a vacuum suction. Alternatively, the solid/injection conduit 166 may be used for the injection of active components in the fluid in the housing, for example, of improving fluid phase separation.

The lower end of the housing 4 is provided with a hole 182, in which they are [...] a fill or bungs insulation 184 and a pressure balanced valve. 0.186, both of conventional design. The bore 182 can be used to provision of jet or circulating sea water, sludge or cements, the installation time of the housing 4 in the sea bed.

The operation of the assembly in Figures associated will be described with respect to fluid separation of two phases of oil and water. A stream of mixed phase since this is experienced in water recovered from fluids production of a subterranean well. Typically, in such a current, the oil is suspended as droplets in the aqueous phase bulky, that are not susceptible to coalescence and separation using conventional techniques of gravity separation and are insufficient mass to segregation under centrifugal forces low. To be suitable for [...] in a subterranean formation, the oil should be removed from the water to a concentration below 400 ppm. This is achieved using the method and apparatus of the present invention in the embodiment shown Figures associated, as follows:

the current oil/water mixed phase is fed to the assembly 2 abeam conduit fluid feed 60 and enters the collector fluid inlet 58, from where it is delivered to one or more sets of helical abeam of the respective separation 8 inlet conduit 56, the flow through which is controlled by respective valve 62 and by a one way check valve 63. This allows the general flow is segregated portions is divided and manageable for distribution to respective sets of helical separation. As described above, the number and sets 8 helical separation being used are selected to have combined with the volumetric flow rate of the feed stream to be processed. As cited, it is an advantage of the present invention assembly, in particular as shown in Figures associated with, a wide range of flow rates can be accommodated volumetric, without any reduction in separation efficiency. Indeed, the ability to select a combination of different sized sets of helical separation allows the system to be suited for a very wide range of flow rates and fluid compositions, while allowed separation processes operate under their optimal conditions and a high efficiency.

From each inlet conduit 56, the oil/water stream enters the respective bore 54 in the body of the radial inlet 22, through opening 52 in tangential uppermost portion of the feed conduit of the respective cylindrical helical separation assembly 8, as shown in Figures 3 and 4. the fluid stream enters the feed conduit selected cylindrical tangentially, rough [...] where a separation occurs. This allows the masses are general phase split and start PFA separate and to form the current in a plurality of discreet phases, before the fluid enter the helical flow travel. As the operation of each helical separation is identical, with the only difference being the size of the assembly and its volumetric production, the operation of only a single helical separation 8 will be described, for clarity.

The current oil/water entering the separation assembly 8 is made helical flow in a pattern of rotation, as it descends by uppermost region 104, as seen in Figure 4. oil/water then enters in stabilization region fluid flow 106 and enters the flow travel formed by helical impeller 108. The function of the uppermost region 104 and the stabilization region fluid flow 106 is to generate a fluid flow pattern uniform rotating in current oil/water. The current flowing through the various conduits and tubes upstream of the separation assembly 2 will provide current to a turbulent flow regime, wherein the Reynolds number is significantly above the critical Reynolds number when inlet in the separation assembly 8. a helical flow pattern such turbulent non will provide a high separation efficiency of oil droplets of the water. Thereby, the uppermost region 104 and flow stabilization region 106 are operated for stabilizing of flow regime, so that the Reynolds number is below the critical number. In other words, the Reynolds number of the fluid flow is driven into below the value in which there arises a turbulent flow. Preferably, the flow stabilization region 106 is of length sufficient for the flow regime of fluid becomes sheet. At least the flow regime should be in the transition state, preferably with a Reynolds number in ' towards the lower end of the transition range.

In stabilization region flow 106, the transition state and the compact helical flow pattern will generate high centrifugal forces within a fluid, forcing even drops of fluid to migrate according to their respective specific weights. This action encourages coalescence of small droplets into larger droplets, which, in turn, due to their larger masses, experience a higher force and accelerate the phase separation. One advantage of a forced flow in stabilization region flow 106 is that it significantly increases the critical Reynolds number, allowing the Reynolds number is considerably higher, but still within the laminar flow regime than for a flow in an open. This in turn allows fluid to flow at a speed significantly higher along the helical travel.

Stabilization region while letting fluid flow 106, the current oil/water immediately enters the upper end region of fluid separation 110 and travel formed by helical flow impeller 112. In this region, the main portion of the oil droplets is large enough to be collected and separated from water in oil/water stream is removed from the current. The action of high centrifugal forces in small oil droplets and the action of separation at various stages, as the flow is forced through the helix, are represented in Figures 5 diagrammatic form the 5c. In upper regions of fluid separation region 110, as shown in Figure 5, the rotating flow of the fluid stream causes the oil droplets of lighter migrates to the upper inner region of the travel helical flow, as seen in Figure 5. This movement progresses along the length of the helical flow travel, as shown in Figures 5b and 5c. The oil being collected in the upper region of the travel inner helical flow flows through the windows in the light fluid conduit 102 and travels upward in the conduit for the gas separation zone 30 - liquid in the buffer 24, as shown in Figure 2. any gas in the oil at this point is collected at the upper region of the separation zone gas - liquid 30 is removed within the through 32 and conduit 34 gas recovery. The oil is removed from the buffer assembly 24 way the side hole 35 in the lower buffer and fluid conduit 37. any water in the oil reaching dirtthat buffer assembly 24 returns to the housing 4 by bores 48 in the body inlet [...] 22.

While letting the region of fluid separation 110, the liquid remaining, consisting essentially of water with minimal amounts of oil, enters the region enhancement fluid speed 116 and the upper end of the travel provided by helical flow impeller 118. In this region, the rotational speed of the current is increased. As a result, the Reynolds number of the current increases and can approach the critical value. The stream velocity is increased sufficiently for producing a stable vortex in the portion of the cylindrical conduit 100 immediately downstream end region enhancement fluid speed 116. The vortex is stabilized in the open end of the impeller 112 and collected with the aid of inverted cone 124 and 126 vortex tube at the lower end of fluid conduit light 102. Under the action of the pivoting motion of the fluid in the vortex, the remaining oil droplets migrate to the center of the vortex and enter the lower end of the fluid conduit light from where they pass to the buffer assembly 24, as discussed above.

remaining liquid flows down at cylindrical conduit and exits via angled window 120 to enter the main volume of the housing 4. in operation, the main body of the housing 4 is filled with liquid, the lower region being filled with water and the upper region being filled with the oil lighter. This entire assembly is operated so that the water/oil interface level is above the maximum high cylindrical conduit 100 of helical separation 8. In the main volume of the housing 4, two actions improve separating any oil droplets of the remaining water. The first action is a direct gravity separation, by the droplets are made lighter oil rising within the housing and entering into upper region.

oil collected in this region will the housing 4 abeam bores in the body inlet [...] 22 to enter separation zone gas liquid in buffer assembly 24. The oil is removed from the buffer assembly as described above.

in the second mode of operation the main volume [...] - is a additional rotary separation. The action of the angled outlet 120 is for induction of a slowly rotating phase substantially of water within the lower housing region 4. the rotary water stream descends in the allo - [...] stabilization region through the fluid 10. As the stream of water passes by inverted cone 170 and 172 helical finger, its rotation speed is increased, before the water stream entering the region of fluid separation - additional fluid 12. in this region, the oil droplets remaining is made to migrate the center of the housing 4, on a - of they pass through windows 174 in the secondary fluid conduit light 160. Within this conduit, the oil droplets move upward in front of the outlets 120 sets 8 helical separation and enter the upper region housing 4.

The water leaving the region of fluid separation - additional fluid 12 will contain only very minimal or trace oil and will be suitable for [...] in a subterranean formation or for disposal of other forms. Water is removed from the array in the scrap region 14 pass through windows 180 in fluid conduit 164 weighed. The water in this conduit flows upwardly for the set of buffer 24 and leaves the assembly 2 abeam wellbore side of the liquid conduit 40 and 42.

Any solid materials, such as a sediment or silt, may be collected in the lowermost region of the housing 4 and removed, such periodic or continuous, through conduit 166/solid injection.

solid/injection conduit 166 also provides for a means for introduction of components in the fluids in the housing 4, such as improvers separation, as can be required for improving separation efficiency of the assembly. in general.

A portion of the water removed from the fluid removal section 14 can be recirculated to the inlet conduit 60, so PFA adjust the volumetric flow rate of fluid through the assembly. This may be necessary, for example, to the provision of rotational speed sufficient current oil water separation assemblies 8 helical.

control and monitoring of the overall system are obtained using an array of injection lines, monitoring and sampling. As cited above, the body cylindrical inlet 22 is formed with a plurality of radial holes 55 connected at their inner ends to respective control lines 53. As shown more clearly in Figure 9, control lines 53 extend in a downstream direction to [...] within the housing 4. the bolt holes 55 radial lines and control 53 may be used for injecting components in fluid phase in volume within the housing, such as additives and enhance separation. A gas may be injected through one or more of these lines, so as to provide a flotation system within a gas phase in liquid volume.

A particular use for control lines 53 is to determine and monitor the interface between fluid phase light-heavy fluid phase within the housing 4. as described above, the fluid phase light will be collected from upstream and rise within the housing to occupy the uppermost regions of the housing, as shown in Figures.

For a efficient operation of the separation process, is necessary to identify the interface between the two phases. In operation, this may be a well defined 15. Alternatively, depending on the nature of the fluids [...], the interface may be poorly defined. For example, in the case of breaking of oil dispersed in an aqueous continuous phase, the interface may extend for several meters and comprise an emulsion of oil and water.

The technique of determining position of the interface 15 is shown schematically in Figure 10. A control line 53 is shown extending to the housing 4, lower end of which defines a datum 19. The pressure fluid injected into the SP control line 53 is measured by a sensor. Similarly, the pressure pH within the housing in its uppermost end is measured. For the determination of the interface 15 on an oil fluid/water, clean oil, for example, that was removed from the fluid conduit light after a separation in the array of a specific weight known is introduced into one or more control lines 53.

The pressure in the control line is measured and compared with the pressure at the exit of the fluid conduit light. The height between the [...] 19 overruns and the interface is determined using the formula:

overruns=([...])/([...]) where HW is the height between the [...] and the interface 15; SP is the pressure of the oil injected into the control line 53; pH is the pressure at the uppermost end of the housing 4; DV is the specific weight of the water and is the specific weight of the oil injected. A formula similar applied to other systems of fluid.

A feed constant light fluid, such as oil, is maintained by control line 53, so PFA allow the system actively monitor interface changes. Generally, the system will be operated with a predetermined operating level 16, as shown in Figure 10, with a high point and a low point 17 18 interface, defining the operating range acceptable fluid/fluid interface. A movement of the system outside of this range may be used to trigger an alarm and/or for initiating a corrective operation, such as the injection through one or more control lines 53 of a volume of fluid light or heavy fluid. Alternately or additionally, one or more of pumps or an outgoing pressure regulating inlet around the system can be adjusted, depending on the required correction. The corrective action may include the recirculation of a portion of the heavier fluid.

As cited above, the arrangement of the present invention is particularly suitable for application in a modular. In a preferred arrangement, a separation module comprises a set of helical separation, as described in general and in specific details above and shown in Figures associated, indicated by reference number 8. the general assembly helical separation can be provided in a variety of different sizes, in particular in a range of different nominal diameters. This variation possible in the size of the separation module is an advantage of the present invention, by allowing a wide range of flow rates of fluid and compositions is accommodated. There are many forms by which the modular approach of the present invention may be applied.

Firstly, the sets of helical separation larger size can accommodate larger fluid flow rates. Referring to Figure 11, there is shown a graph of flow rates and operating pressures for a range of sets of helical separation 8, as shown in Figures associated. The operating ranges and parameters are given for separation assemblies having helical diameters of a nominal 10 cm, 12.5 cm, 18 cm and 15.25 cm (4, 5, 6 and 7 inches) (numbered 1 4 in Figure 11) and for operating droplet separation of crude oil of a stream of water. A current since this is typical of water streams contaminated with oil encountered during drilling operations in underground wells and producing oil and gas. As a first approach to accommodating a given fluid stream and flow rate, is merely required select proper size assembly helical separation, for example, from a graph as in Figure 11.

If the current has a flow rate to be processed to flow rate exceeding maximum operating assembly helical separation, the current may be split and a plurality of such assemblies can be operated in parallel. A additionally of applying the modular approach of the present invention is selecting a plurality. An appropriate selection of the sizes of the plurality of separation allows a helical assemblies of different sizes is determined to match the given current and flow rate.

A complication arises when the flow rate and/or the composition of the fluid stream to be processed vary depending well or wells are placed in current or stationary and working life time of separation. This situation has probability of being found in the case of oil wells and gas in high-sea, is preferred in these [...] providing a remote that can operate for extended time periods, typically of many years, with little or no adjustment or maintenance. A problem arises with a separation in these remote locations, as a result of the flow rate of fluid and of the composition produced from the downhole variation over time. Advantageously, the present invention provides a system that may be installed and operated to accommodate a range of flow rates and compositions by changing over time.

A set embodying the concepts of the present invention is adapted to accommodate these changes into the fluid stream over time comprises a plurality of sets of helical 8 separation of a variety of nominal sizes. As the flow rate of fluid and compositions change, assemblies are placed in individual helical separation line down from line and originate a optimum separation efficiency. Referring to Figure 12, is shown as an example additional a graph, in which the flow rate of a stream of water contaminated with oil, as obtained from the oil production of a subterranean well, is combined with combinations of sets of Figure 11 1 4 helical separation. As will be seen, at flow rates low, a set of single helical separation size proper may be employed. As the flow rate increases, it is necessary to employ combinations of two or more sets of the proper size. The number and size are selected to separation assemblies with the total flow rate required, while still allowing each individual assembly operates address its operating range and its optimum efficiency.

Referring to Figure 11, there is shown an histogram dual vertical axis. The vertical axis 200 on the right side indicates the flow rate of fluid to each helix, while the vertical axis 202 on the left side shows the pressure differential across an impeller. The base of the histogram identifies a set of helical separation single sized. For each set of helical separation, the vertical column 204 left describes the minimum flow rate to provide sufficient centrifugal forces within a fluid flow rate and the maximum acceptable to 206 if remain less critical of Reynolds number. The column 208 to the right of each set of helical separation shows the minimum allowable differential pressure to provide a centrifugal separation within the acceptable differential pressure and maximum 210 to remain below the critical Reynolds number. A fault in the flow rate in the operate with correct pressure differential within the band of operation for each set of helical separation will result in a fluid being conveyed through the light system and pollution of the heavier fluid phase collected. This makes the heavier fluid for pumping well below unacceptable, unless recirculated to the system inlet separation phases of lighter fluid removed.

Therefore, as the total flow rate increases or decreases, the sets of helical separation cannot be simply open or Fe - [...], since fluid flow to other sets of open helical separation could change and be outside the aforementioned operating windows. For the general system perform the load required for separation a wide range of flow rates of fluid, combinations of intermediate helical separation assembly have to be selected.

Turning in especially for examples of Figure 11, at flow rates very low, that be below 1200 [...], a set of single helical separation, number 1 in Figure 11, having a nominal diameter of 10 cm (4 inches) is applied. The operation optimal set yarn is obtained by using a recirculation flow rate fresh water to supplementation of the low current to be processed. As the flow rate of the stream to be processed increases, helical separation assemblies 2, 3 and 4 are placed in line, alone or in combination. The rates up to 5500 [...] may be accommodated, using a single helical separation 4, having a nominal diameter of 18 cm (7 inches). To be able to cover a full range of flow, will be required that combinations of two or more assemblies illustrated in Figure 11 are employed.

Figure 12 shows a histogram with the vertical axis 212 indicating the flow rate of total fluid accommodated by 2. assembly to be the base of the histogram identifies the step 220 and the maximum flow rate flow rate minimum step 222 that can be processed using the separation assemblies 224 shown in the steps identified helical coextrusion OM - 225. Each of sets of helical separation was numbered, and individual arrays constituting the given identified. The safe operating range for each assembly 226 has been identified. Thus, a flow rate of 42,400 [...] is accommodated using a seven sets of helical diameter nominal separation 18 cm (7 inches) (4 in Figure 11 assembly) and a set of nominal diameter of 15.25 cm (6 inches) (3 in Figure 11 assembly), identified as 16 in Figure 12.

As will be seen in Figure 12, the operating range safety 226 assembly selected for each range overlaps two adjacent operation combinations. As the flow rate increases and the total fluid flow rate of a given maximum operating assembly 228, the operation is switched to the next higher assembly, as identified in steps 225. When the flow rate of total fluid drops and approaches the minimum flow rate of the operating 230, the operation is switched to the next lower assembly. Thus, a separation operation smooth and continuous fluid may be obtained from zero up to a flow rate of fluid maximum total production 232 of the complete assembly 2.

As will be appreciated, during the operation of the present invention assembly, when applied in a modular approach, individual helical separation assemblies are placed on-line and taken from Li - tical, as the flow rate of fluid and the composition change. This requires that each set has the given starting and is stopped. Preferred methods for from assemblies and stop them are provided as aspects of the present invention.

So that separation required is obtained in the various s - of the present invention [...] separation, it is necessary that the flow rate of fluid is above a critical minimum value, as indicated at 204 value for each set of helical separation 11 shown in Figure. At flow rates below this critical value, lighter fluid phases will not be completely removed will contaminate phases produced in the process heavier fluid. This feature makes undesirable simply stop and starting in sets individual separation using only the fluid stream to be separated. To overcome this problem, it is preferred to place each separation assembly helical line using a purge of a heavy fluid clean.

As cited above and as shown in Figures 2 and 3, the inlet assembly of the system comprises a fluid manifold 64 flush [...] by a fluid conduit 70 flush. The flow of the fluid flush from the collector 64 for each set of helical separation 8 is controlled by a fluid valve 68 flush. When the flush fluid valve 68 for a given set of helical separation 8 is open, a fluid flush light (as clean water in the case of a set separating oil droplets of the water produced) is introduced downstream of the valve 62 and valve 63 retaining controling the flow of fluid to be processed. When starting up a given helical separation, the relevant valve 62 and 63 one-are closed and valve 68 liquor flush fluid, to the provision of a fluid stream flow rate above the minimum critical to separation. Once the flow has been established, the valve 62 is opened. It is preferable to have the flush fluid pressure above the pressure of fluid stream, such PFA ensure that the fluid stream flush has dominance over the fluid stream being processed.

Thus, when the valve 62 is opened, the fluid stream will not flow, since the purge fluid pressure higher will replace the washer retaining closed. As the purge valve 68 is gradually closed, the pressure of fluid entering the bore radially flush 54 will fall, allowing one-to open 63. Thus, the fluid stream to be processed replaces the flush fluid decreasing, as the purge valve closes, putting the assembly fully in line 8 helical separation.

To stop a given helical separation, opposite procedure is followed. Thus, the flush fluid valve proper 68 is gradually open, by supplementing the fluid stream with flush fluid. The check valve 63 prevents a higher pressure downstream of the valve 62 entering the system and feed fluid flowing downstream. The flush fluid, because it was at higher pressure, gradually close the check valve 63, in turn slowly stopping flow of feed fluid, to a static flow be obtained. The valve is then closed at this point.

The purge valve 68 remains open to a sufficient fluid has passed completely to purge the entire helical separation 8 the waste fluid being processed. The purge valve 68 is then closed. The assembly 8 is left helical separation with only a fluid flush clean and allowed to remain in this state until off-line time as a change in the flow rate additional total fluid require it to be placed in line.

It is important that the helical separation assemblies 8 to be put out of line in a clean state is purged, the flow rate of fluid since starting 8 through a set flow rate below the minimum will be critical to achieve complete separation. If the separation is allowed to helical containing a fluid being processed, this would be discharged to the zone of clean fluid downstream upon starting. This would result in a contamination of the fluid fractions separated. This contaminated fluid should be recirculated to the inlet of the assembly 2 to be processed again. This would result in a production flow head well have to be reduced or even stopped, until fluid [...] have been processed. As will be appreciated, this is not acceptable for the process of making continuous well, in particular given the frequency wherein the separation assemblies being placed in 8 helical line and taken from read should change.

The feed valve fluid flush 68 may be a pressure regulator, a flow control valve, a ball valve or hopper. The separation can be held in this state helical until needed placing it in line again.

The operation of the present invention, in particular embodiments shown in Figures associated, can be described in detail in relation to a current multiphase comprising oil and water. It will be appreciated that the assembly and method of the present invention may be employed for the separation of liquid streams - multiphase liquid.

The stream may contain two, three or more phases, which can be separated in accordance with the weights relative specific liquids [...]. In addition, the invention may be employed for the separation of gas streams - multiphase liquid in a similar manner.

SR!VOLTS!NA!Dona 1. method of separating a multiphase fluid stream comprising an fluid heavier component and a lighter fluid, the method comprising:

cause the fluid to flow along a helical flow travel, wherein the critical Reynolds number of the fluid stream is high, the fluid stream flowing at a Reynolds number below the critical number raised, the fluid stream flowing at a rate sufficient to cause the fluid phases from separating.

2. method, according to claim 1, wherein the critical Reynolds number is greater than 10,000.

3. method, according to claim 2, wherein the critical Reynolds number is greater than 100,000.

4. method of separating a multiphase fluid stream comprising an fluid heavier component and a lighter fluid, the method comprising:

cause the fluid to flow along a helical flow travel extending around a central conduit, the fluid flowing at a rate sufficient to cause the component lighter fluid to move into the internal region of the helical flow travel; and collecting the lighter fluid component in central conduit.

5. method, according to claim 4, wherein the helical flow travel is such that the critical Reynolds number of the fluid flow to be elevated, the fluid stream flowing at a Reynolds number below the critical high number.

6. method of separating a multiphase fluid stream comprising an fluid heavier component and a lighter fluid, the method comprising:

cause the fluid to flow along a first helical flow travel, travel the first flow having a first helical pitch, the first flow being substantially helical travel long for establishing a fluid flow pattern rotating stabilized