Multiphase separation system

A system and method for separation of liquids and gases within a multiphase fluid are provided herein. The method includes flowing a multiphase fluid into a number of divisions within a multiphase separation system, wherein the divisions are configured to lower a velocity of the multiphase fluid. The method also includes separating the multiphase fluid among a number of lower pipes and a number of upper pipes, wherein each lower pipe includes an expansion zone configured to lower a pressure within the lower pipe to allow entrained liquids to drain from a corresponding upper pipe via a downcomer.

FIELD OF THE INVENTION

The present techniques provide for the separation of gases and liquids within production fluids. More specifically, the techniques provide for the separation of production fluids into gases and liquids using a subsea multiphase separation system.

BACKGROUND

This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present techniques. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present techniques. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art.

Any of a number of subsea separation techniques may be used to enhance the amount of oil and gas recovered from subsea wells. However, subsea separation at water depths greater 1500 meters becomes especially challenging due to the environmental conditions. As water depth increases, the external pressure on a vessel created by the hydrostatic head increases the required wall thickness for vessels used for subsea processing. At water depths greater than 1500 meters, this wall thickness has increased to such an extent that typical gravity separation is not practical. In addition, vessels with such a large wall thickness can be a challenge to fabricate, and the added material and weight can impact project economics, as well as the availability of the vessel for maintenance. As a result, large diameter separators often cannot be used at such depths.

SUMMARY

An exemplary embodiment provides a multiphase separation system including an inlet line configured to allow a multiphase fluid to flow into the multiphase separation system. The inlet line includes a number of divisions configured to lower a velocity of the multiphase fluid and feed the multiphase fluid into a distribution header. The distribution header is configured to split the multiphase fluid among a number of lower pipes, wherein each lower pipe includes an expansion zone. The system also includes a number of upper pipes branching from the lower pipes. The expansion zones are configured to lower a pressure within the lower pipes to allow entrained liquids to drain from the upper pipes via a corresponding downcomer.

Another exemplary embodiment provides a method for separation of liquids and gases within a multiphase fluid. The method includes flowing a multiphase fluid into a number of divisions within a multiphase separation system, wherein the divisions are configured to lower a velocity of the multiphase fluid. The method also includes separating the multiphase fluid among a number of lower pipes and a number of upper pipes, wherein each lower pipe includes an expansion zone configured to lower a pressure within the lower pipe to allow entrained liquids to drain from a corresponding upper pipe via a downcomer.

DETAILED DESCRIPTION

In the following detailed description section, specific embodiments of the present techniques are described. However, to the extent that the following description is specific to a particular embodiment or a particular use of the present techniques, this is intended to be for exemplary purposes only and simply provides a description of the exemplary embodiments. Accordingly, the techniques are not limited to the specific embodiments described below, but rather, include all alternatives, modifications, and equivalents falling within the true spirit and scope of the appended claims.

As discussed above, traditional large diameter separators face technical challenges at depths greater than approximately 1500 meters. Thus, embodiments described herein provide an unconventional separation system that is capable of achieving acceptable gas-liquid separation and damping potential flow fluctuations, while meeting the size and weight restrictions imposed on deepwater processing units. Further, the separation system can be designed to pipe code instead of vessel code, which may provide cost and weight savings. In many cases, for a given pressure class, the required wall thickness for a pipe is less than the required wall thickness for a corresponding vessel.

According to embodiments described herein, a compact, subsea multiphase separation system is used to enhance subsea well production, especially in deepwater and Arctic environments. In various embodiments, the subsea multiphase separation system is a four phase subsea separator that is configured to separate production fluids into a gas phase, an oil phase, an aqueous phase, and a solid phase. In other words, subsea separation may be used to create single phase streams. This may allow for the usage of single phase pumps, which are more efficient and can achieve larger pressure differentials compared to multiphase pumps. In order to pump a single phase stream, one single phase pump may be sufficient. In contrast, in order to pump a multiphase stream, a series of multiphase pumps may be used to achieve the same pressure differential, especially for high boosting applications.

The separation process described herein may be used to achieve bulk removal of aqueous fluids from production fluids. The removal of aqueous fluids is termed water removal herein, although this may be understood to include water with other contaminants, such as salts or other miscible fluids. Such bulk water removal may mitigate flow assurance concerns, by allowing substantially pure oil and/or gas streams to be sent to the surface. These substantially pure streams will form lower amounts of hydrates, such as methane clathrates, thus lowering the risk of plugging or flow restrictions. Further, corrosion concerns can be reduced or eliminated. The sand and water by-product streams can then be disposed topsides to dedicated disposal zones, reservoirs, the seabed, or the like.

Bulk water removal may also result in a decrease in the hydrostatic head acting on the reservoir, thus increasing both the reservoir drive and production. Further, the separation process may be used to reduce flow line infrastructure, reduce the number of topside water treating facilities, reduce power and pumping requirements, and de-bottleneck existing facilities that are challenged with declining production rates due to increased water cuts.

As used herein, the term “slug” refers to a small volume of fluid that is entrained within the production fluids and is often of a higher density than the production fluids, for example, a liquid zone carried along by gas flow in a pipeline. Slugs may affect the flow characteristics of the production fluids. In addition, slugs exiting a pipeline may overload the gas-liquid handling capacity of the subsea, topsides, or onshore processing facility at the pipeline outlet. Thus, according to embodiments described herein, one or more subsea multiphase slug catchers may be used to dampen or remove the slugs from the production fluids before the production fluids enter the export pipelines.

FIG. 1is a block diagram showing a system100for separating production fluids102into a gas stream104and a liquid stream106using a multiphase separation system108. The production fluids102may be hydrocarbon fluids that include a mixture of natural gas, oil, brine, and solid impurities, such as sand. The production fluids102may be obtained from a subsea well110, as indicated by arrow112. The production fluids102may be obtained from the subsea well110via any type of subsea production system (not shown) that is configured to produce hydrocarbons from subsea locations.

In an embodiment, the production fluids102are flowed into the multiphase separation system108, as indicated by arrow114. The multiphase separation system108may be any type of vessel that is configured to achieve bulk separation of gas and liquid from the production fluids102. In addition, the multiphase separation system108may remove slugs from the production fluids102. The multiphase separation system108may be implemented within a subsea environment.

Within the multiphase separation system108, the production fluids108may be separated into the gas stream104and the liquid stream106, as indicated by arrows116and118, respectively. The gas stream104may include natural gas, while the liquid stream106may include water, oil, and other residual impurities, such as sand. Designs for the multiphase separation system108, as well as the mechanisms by which the multiphase separation system108may affect the quality of the separated gas stream104and the separated liquid stream106, are described with respect toFIGS. 2-8.

In some embodiments, the gas stream104is flowed to downstream equipment120, as indicated by arrow122. The downstream equipment120may include, for example, any type of downstream gas processing equipment, such as a gas compressor, gas treatment facility, gas polishing device, or the like, or a gas pipeline. In addition, the liquid stream106may be flowed to downstream equipment124, as indicated by arrow126. The downstream equipment124may include, for example, oil and water pre-treating or coalescence equipment, such as a heating system, chemical injection system, electrostatic coalescer, or the like, a pipe separator or cyclone for oil-water separation, or a liquid export pipeline.

The block diagram ofFIG. 1is not intended to indicate that the system100is to include all of the components shown inFIG. 1. Further, any number of additional components may be included within the system100, depending on the details of the specific implementation. For example, the multiphase separation system108can be designed to achieve liquid/liquid separation, thus delivering two substantially pure oil and water streams to the downstream equipment124. Further, multiphase and single phase desanders may be placed upstream and/or downstream of the multiphase separation system108.

FIG. 2is a perspective view of a multiphase separation system200. The multiphase separation system200may include an inlet line202configured to feed the multiphase fluid into a circular distribution header204. The multiphase fluid may be any type of fluid that includes both liquid and gaseous components. For example, the multiphase fluid may be production fluids from a subsea well. The circular distribution header204may be coupled to a number of upper lines206and a number of lower lines208. The upper lines206and the lower lines208may be perpendicular to the circular distribution header204.

Each upper line206may feed gases within the multiphase fluid into a circular gas header210. The circular gas header210may be in a second plane that is above and substantially parallel to the circular distribution header204. In addition, each lower line208may feed liquids within the multiphase fluid into a circular liquid header212. The circular liquid header212may be below and substantially parallel to the circular distribution header204.

A gas outlet line214may be coupled to the circular gas header210and may be configured to flow the gases out of the multiphase separation system200. A liquid outlet line216may be coupled to the circular liquid header212and may be configured to flow the liquids out of the multiphase separation system200. The gas outlet line214and the liquid outlet line216may be coupled via a downcomer218. The downcomer218may be configured at a right angle or an oblique angle.

The downcomer218may allow entrained liquids within the gases to flow from the gas outlet line214to the liquid outlet line216. In addition, the downcomer218may allow entrained gases within the liquids to flow from the liquid outlet line216to the gas outlet line214. However, in some embodiments, the separation of gases and liquids may be sufficient in the upper lines206and the lower lines208perpendicular to the circular distribution header204. In this case, the downcomer218may be omitted from the multiphase separation system200.

The schematic ofFIG. 2is not intended to indicate that the subsea multiphase separation system200is to include all of the components shown inFIG. 2. Further, any number of additional components may be included within the subsea multiphase separation system200, depending on the details of the specific implementation. For example, the liquid outlet line216may be extended, with or without an optional sealing downcomer, to increase residence time in the liquid phase and achieve oil/water separation. This may allow for the enhancement or the elimination of downstream oil/water separation steps and equipment. In addition, the liquid outlet line216may include separate outlet lines for flowing the oil and water out of the multiphase separation system200.

FIG. 3is a side view of the multiphase separation system200ofFIG. 2. As shown inFIG. 3, the circular distribution header204may be in the same plane as the inlet line202. Thus, the multiphase fluid may flow directly into the circular distribution header204. Due to the configuration of the circular distribution header204, the multiphase fluid flow may initially distribute along two flow paths within the circular distribution header204, resulting in a reduction in velocity of the multiphase fluid as it flows throughout the circular distribution header204. In some embodiments, such a reduction in velocity of the multiphase fluid dissipates any slugs within the multiphase fluid. In addition, the circular distribution header204may act as a stratification section that is configured to perform an initial bulk separation of gases and liquids within the multiphase fluid.

The upper lines206may be perpendicular to the circular distribution header204and may couple the circular distribution header204to the circular gas header210. The lower lines208may be perpendicular to the circular distribution header204and may couple the circular distribution header204to the circular liquid header212. The circular gas header210and the circular liquid header212may be parallel to the circular distribution header204.

In some embodiments, the circular gas header210acts as a droplet separation section configured to remove entrained liquids from the gases within the circular gas header210. In addition, in some embodiments, the circular liquid header212acts as a liquid degassing section configured to remove entrained gases from the liquids within the circular liquid header212.

FIG. 4is a process flow diagram showing a method400for separating gases and liquids within a multiphase fluid. In some embodiments, the multiphase separation system500discussed below with respect toFIGS. 5 and 6is used to implement the method400. In other embodiments, the multiphase separation system700discussed below with respect toFIGS. 7 and 8is used to implement the method400.

The method begins at block402, at which the multiphase fluid is flowed into a number of divisions configured to lower a velocity of the multiphase fluid. From the divisions, the multiphase fluid may be flowed into a distribution header.

At block404, the multiphase fluid is separated among a number of lower pipes and a number of upper pipes. Each lower pipe includes an expansion zone configured to lower a pressure within the lower pipe to allow entrained liquids to drain from a corresponding upper pipe via a downcomer.

Liquids flowing through the lower pipes may be collected within a liquid header. The liquids may then be flowed out of the multiphase separation system via a liquid outlet line. Gases flowing through the upper pipes may be collected within a gas header. The gases may then be flowed out of the multiphase separation system via a gas outlet line.

The process flow diagram ofFIG. 4is not intended to indicate that the steps of the method400are to be executed in any particular order, or that all of the steps of the method400are to be included in every cases. Further, any number of additional steps not shown inFIG. 4may be included within the method400, depending on the details of the specific implementation. For example, gases may be flowed from the multiphase separation system to downstream liquid processing equipment or a gas export line, and liquids may be flowed from the multiphase separation system to downstream gas processing equipment or a liquid export line.

In various embodiments, the multiphase fluid is flowed into a distribution header configured to split the multiphase fluid among a number of pipes in a same plane as the distribution header. The multiphase fluid may be separated into gases and liquids within an expansion zone of each pipe. The gases within each pipe may be flowed into a corresponding upper pipe in a second plane disposed above a plane of the distribution header, and the liquids within each pipe may be flowed into a corresponding lower pipe in the plane of the distribution header. Entrained liquids within each upper pipe may then be drained to a corresponding lower pipe via a downcomer. In addition, entrained gases within each lower pipe may be flowed to a corresponding upper pipe via the downcomer.

In other embodiments, the multiphase fluid is separated into gases and liquids within a distribution header. The gases may be flowed into a number of upper pipes in a first plane disposed above the distribution header, and the liquids may be flowed into a number of lower pipes in a second plane disposed below the distribution header. The gases may be flowed out of the multiphase separation system via a gas outlet line, and the liquids may be flowed out of the multiphase separation system via a liquid outlet line. In addition, entrained liquids within the upper pipes may be drained to corresponding lower pipes via downcomers.

FIG. 5is a perspective view of another multiphase separation system500. The multiphase separation system500may include an inlet line502that is configured to allow a multiphase fluid to flow into the multiphase separation system500. The inlet line502may include a number of divisions504that are configured to lower the velocity of the multiphase fluid and feed the multiphase fluid into a distribution header506.

The distribution header506may be configured to split the multiphase fluid among a number of upper fingers508and a number of lower fingers510. Each upper finger508is angled upward to feed into a corresponding upper pipe512in a first plane disposed above and substantially parallel to the distribution header506. Each lower finger510is angled downward to feed into a corresponding lower pipe514in a second plane disposed below and substantially parallel to the distribution header506. In addition, each upper pipe512may be coupled to a corresponding lower pipe514via a downcomer516. The downcomer516may be configured perpendicular to the upper pipes512and lower pipes514, or may be at an oblique angle.

Each lower pipe514may include an expansion zone518that is configured to lower a velocity and a pressure of liquids within the lower pipe514. This may allow entrained gases within the liquids to rise to the corresponding upper pipe512via the downcomer516.

Each upper pipe512may feed into a common gas header520. The gas header520may be configured to lower a velocity of gases within the upper pipe512to allow entrained liquids, such as droplets, within the gases to coalesce and drop to the corresponding lower pipe514via the downcomer516.

The multiphase separation system500may also include a liquid header522for collecting the liquids and flowing the liquids out of the multiphase separation system500via liquid outlet lines524. In addition, the gas header520may include gas outlet lines526for flowing the gases out of the multiphase separation system500.

The schematic ofFIG. 5is not intended to indicate that the subsea multiphase separation system500is to include all of the components shown inFIG. 5. Further, any number of additional components may be included within the subsea multiphase separation system500, depending on the details of the specific implementation. For example, the lower pipe514may be extended, with or without an optional sealing downcomer, to increase residence time in the liquid phase and achieve oil/water separation. This may allow for the enhancement or the elimination of downstream oil/water separation steps and equipment. Separate oil and water outlets can be included in the liquid header522for flowing the oil and water out of the multiphase separation system500.

FIG. 6is a side view of the multiphase separation system500ofFIG. 5. As shown inFIG. 6, the divisions504may be in the same plane as the inlet line502. Thus, the multiphase fluid may be flowed directly into the divisions504from the inlet line502. However, because the multiphase fluid is split among the divisions504, the velocity of the multiphase fluid is reduced. In some embodiments, the reduction in velocity of the multiphase fluid dissipates any slugs within the multiphase fluid.

The distribution header506may also be in the same plane as the inlet line502. Thus, the multiphase fluid may be flowed directly into the distribution header506from the divisions504. Within the distribution header506, the multiphase fluid may be split among the upper fingers508and the lower fingers510. This may further reduce the velocity of the multiphase fluid.

In some embodiments, the distribution header506is a stratification section that is configured to perform an initial bulk separation of gases and liquids within the multiphase fluid. Thus, gases may be flowed into the upper fingers508, and liquids may be flowed into the lower fingers510. The gases may be flowed from the upper fingers508to corresponding upper pipes512, and the liquids may be flowed from the lower fingers510to corresponding lower pipes514. In some embodiments, the upper pipes512are parallel to the lower pipes514.

FIG. 7is a perspective view of another multiphase separation system700. The multiphase separation system700may include an inlet line702configured to allow a multiphase fluid to flow into the multiphase separation system700. The inlet line702may include a number of divisions704configured to lower a velocity of the multiphase fluid and feed the multiphase fluid into a distribution header706.

The distribution header706is configured to split the multiphase fluid among a number of pipes708in a same plane as the distribution header. Each pipe708may include an expansion zone710configured to lower the velocity and the pressure of the multiphase fluid. The multiphase fluid is split between each upper finger712and a corresponding lower pipe714.

Each upper finger712may feed into a corresponding upper pipe716in a second plane disposed above and substantially parallel to the plane of the distribution header706. Each lower pipe714may be in the same plane as the distribution header706. In addition, each upper pipe716may be coupled to a corresponding lower pipe714via a downcomer720. The downcomer720may be configured at a right angle (as shown) or an oblique angle.

Each lower pipe714can be configured to allow entrained gases within liquids to rise to the corresponding upper pipe716via the downcomer720. Each upper pipe716may feed into a common gas header722. The gas header722may be configured to lower a velocity of gases to allow entrained liquid droplets to coalesce and drop to any of the lower pipes714via any of the downcomers720.

The multiphase separation system700may include a liquid header724for collecting the liquids from the lower pipes714and flowing the liquids out of the multiphase separation system700via liquid outlet lines726. In addition, the gas header722may include gas outlet lines728for flowing the gases out of the multiphase separation system700.

The schematic ofFIG. 7is not intended to indicate that the subsea multiphase separation system700is to include all of the components shown inFIG. 7. Further, any number of additional components may be included within the subsea multiphase separation system700, depending on the details of the specific implementation. For example, the lower pipe714may be extended, with or without an optional sealing downcomer, to increase residence time in the liquid phase and achieve oil/water separation. This may allow for the enhancement or the elimination of downstream oil/water separation steps and equipment. Separate oil and water outlets can be included in the liquid header724for flowing the oil and water out of the multiphase separation system700.

FIG. 8is a side view of the multiphase separation system700ofFIG. 7. As shown inFIG. 8, the divisions704may be in the same plane as the inlet line702. Thus, the multiphase fluid may be flowed directly into the divisions704from the inlet line702. However, because the multiphase fluid is split among the divisions704, the velocity of the multiphase fluid is reduced. In some embodiments, such a reduction in velocity of the multiphase fluid dissipates any slugs within the multiphase fluid.

The distribution header706may also be in the same plane as the inlet line702. Thus, the multiphase fluid may be flowed directly into the distribution header706from the divisions704. Within the distribution header706, the multiphase fluid may be split among the pipes708. Within the pipes708, the multiphase fluid may be flowed through the expansion zone710, resulting in a reduction of the pressure and velocity of the multiphase fluid.

The multiphase fluid may then be split between each of the upper fingers712and the corresponding lower pipe714. This may further reduce the velocity of the multiphase fluid. In some embodiments, the distribution header706acts as stratification section that is configured to perform an initial bulk separation of gases and liquids within the multiphase fluid. Thus, gases may be flowed into the upper fingers712, and liquids may remain in the lower pipes714. In addition, the gases may be flowed from the upper fingers712to corresponding upper pipes716. In some embodiments, the upper pipes716are parallel to the lower pipes714.

Embodiments

Embodiments of the invention may include any combinations of the methods and systems shown in the following numbered paragraphs. This is not to be considered a complete listing of all possible embodiments, as any number of variations can be envisioned from the description above.1. A multiphase separation system, including:an inlet line configured to allow a multiphase fluid to flow into the multiphase separation system, the inlet line including a number of divisions configured to lower a velocity of the multiphase fluid and feed the multiphase fluid into a distribution header;the distribution header configured to split the multiphase fluid among a number of lower pipes, wherein each of the number of lower pipes includes an expansion zone upstream of a corresponding downcomer, and wherein the expansion zone is configured to lower a pressure within the number of lower pipes to allow entrained liquids to drain from a number of upper pipes via the corresponding downcomer.2. The multiphase separation system of paragraph 1, including a liquid header for collecting the liquids from the number of lower pipes and flowing the liquids out of the multiphase separation system via a liquid outlet line.3. The multiphase separation system of any of paragraphs 1 or 2, wherein each of the number of upper pipes feeds into a common gas header, and wherein the common gas header includes a gas outlet line for flowing the gases from the number of upper pipes out of the multiphase separation system.4. The multiphase separation system of any of paragraphs 1, 2, or 3, wherein entrained gases within any of the number of lower pipes rise to any of the number of upper pipes via the corresponding downcomer.5. The multiphase separation system of any of paragraphs 1-4, including a stratification section upstream of each expansion zone that is configured to separate gases from liquids within the multiphase fluid.6. The multiphase separation system of any of paragraphs 1-5, wherein the multiphase separation system is implemented within a subsea environment.7. The multiphase separation system of any of paragraphs 1-6, wherein the multiphase separation system includes a slug catcher.8. The multiphase separation system of any of paragraphs 1-7, wherein a desander is located upstream of the inlet line.9. The multiphase separation system of any of paragraphs 1-8, wherein a desander is located downstream of a liquid outlet line.10. The multiphase separation system of any of paragraphs 1-9, including;an oil/water separation section that is coupled to each of a number of lower pipes and is configured to separate the liquids into oil and water;an oil outlet line that is configured to flow the oil out of the multiphase separation system; anda water outlet line that is configured to flow the water out of the multiphase separation system.11. The multiphase separation system of paragraph 10, wherein the oil/water separation section is coupled to each of the number of lower pipes via a sealing downcomer.12. The multiphase separation system of any of paragraphs 1-10, wherein the distribution header is configured to split the multiphase fluid among a number of pipes in a same plane as the distribution header, and wherein:each pipe includes an expansion zone upstream of an upper and a lower finger that is configured to lower a pressure of the multiphase fluid prior to separating the multiphase fluid among the upper finger and the lower finger;each upper finger feeds into a corresponding upper pipe in a second plane disposed above a plane of the distribution header;each lower finger feeds into a corresponding lower pipe in the plane of the distribution header;each upper pipe is coupled to a corresponding lower pipe by a downcomer;each lower pipe is configured to allow entrained gases to rise to the corresponding upper pipe via the downcomer; andeach upper pipe is configured to allow entrained liquids to drain to the corresponding lower pipe via the downcomer.13. The multiphase separation system of paragraph 12, wherein each upper finger is raised at an acute angle relative to the distribution header, and wherein each lower finger is in the plane of the distribution header.14. The multiphase separation system of any of paragraphs 12 or 13, wherein each upper finger includes a droplet separation section configured to remove the entrained liquids from gases.15. The multiphase separation system of any of paragraphs 12, 13, or 14, wherein each lower finger includes a liquid degassing section configured to remove entrained gases from the liquids.16. The multiphase separation system of any of paragraphs 1-10 or 12, wherein the distribution header is configured to split the multiphase fluid among a number of upper fingers and a number of lower fingers, and wherein:each upper finger feeds into a corresponding upper pipe in a first plane disposed above the distribution header;each lower finger feeds into a corresponding lower pipe in a second plane disposed below the distribution header;each upper pipe is coupled to a corresponding lower pipe by a downcomer;each lower pipe includes an expansion zone configured to lower a pressure within the number of lower pipes to allow entrained liquids to drain from the number of upper pipes via a corresponding downcomer.17. The multiphase separation system of paragraph 16, wherein each upper finger is raised at an acute angle relative to the distribution header, and wherein each lower finger is lowered at an acute angle relative to the distribution header.18. The multiphase separation system of any of paragraphs 16 or 17, wherein each upper finger includes a droplet separation section configured to remove the entrained liquids from gases.19. The multiphase separation system of any of paragraphs 16, 17, or 18, wherein each lower finger includes a liquid degassing section configured to remove entrained gases from liquids.20. The multiphase separation system of any of paragraphs 1-10, 12, or 16, wherein the multiphase fluid includes slugs including liquids entrained within gases.21. A method for separation of liquids and gases within a multiphase fluid, including:flowing a multiphase fluid into a number of divisions within a multiphase separation system, wherein the number of divisions are configured to lower a velocity of the multiphase fluid; andseparating the multiphase fluid among a number of lower pipes and a number of upper pipes, wherein each of the number of lower pipes includes an expansion zone upstream of a downcomer that is configured to lower a pressure within the lower pipe to allow entrained liquids to drain from a corresponding upper pipe via the downcomer.22. The method of paragraph 21, including:flowing gases from the multiphase separation system to downstream gas processing equipment or a gas export line; andflowing the liquids from the multiphase separation system to downstream liquid processing equipment or a liquid export line.23. The method of any of paragraphs 21 or 22, including:separating the liquids into oil and water;flowing the oil out of the multiphase separation system via an oil outlet line; andflowing the water out of the multiphase separation system via a water outlet line.24. The method of any of paragraphs 21, 22, or 23, including:collecting the liquids within a liquid header; andflowing the liquids out of the multiphase separation system via a liquid outlet line.25. The method of any of paragraphs 21-24, including:collecting the gases within a gas header; andflowing the gases out of the multiphase separation system via a gas outlet line.26. The method of any of paragraphs 21-25, including:flowing the multiphase fluid into a distribution header configured to split the multiphase fluid among a number of pipes in a same plane as the distribution header;separating the multiphase fluid into gases and liquids within an expansion zone of each of the number of pipes;flowing the gases within each of the number of pipes into a corresponding upper pipe in a second plane disposed above a plane of the distribution header; andflowing the liquids within each of the number of pipes into a corresponding lower pipe in the plane of the distribution header;wherein entrained liquids within each upper pipe are drained to a corresponding lower pipe via a downcomer.27. The method of paragraph 26, including flowing entrained gases within each lower pipe to a corresponding upper pipe via the downcomer.28. The method of any of paragraphs 26 or 27, including lowering a velocity and a pressure of the multiphase fluid by splitting the multiphase fluid among the number of pipes in the same plane as the distribution header.29. The method of any of paragraphs 21-26, including:separating the multiphase fluid into gases and liquids within a distribution header;flowing the gases into a number of upper pipes in a first plane disposed above the distribution header;flowing the liquids into a number of lower pipes in a second plane disposed below the distribution header,flowing the gases out of the multiphase separation system via a gas outlet line; andflowing the liquids out of the multiphase separation system via a liquid outlet line;wherein entrained liquids within any of the number of upper pipes are drained to a corresponding lower pipe via a downcomer.30. The method of paragraph 29, including flowing the gases into the number of upper pipes via a number of upper fingers.31. The method of any of paragraphs 29 or 30, including lowering a velocity and a pressure of the gases within the distribution header.32. The method of any of paragraphs 29, 30, or 31, including flowing the liquids into the number of lower pipes via a number of lower fingers.33. The method of paragraph 32, including separating entrained gases from the liquids within a liquid degassing section of each of the number of lower fingers.34. The method of any of paragraphs 29-32, including lowering a velocity and a pressure of the liquids within the distribution header.

While the present techniques may be susceptible to various modifications and alternative forms, the embodiments discussed above have been shown only by way of example. However, it should again be understood that the techniques is not intended to be limited to the particular embodiments disclosed herein. Indeed, the present techniques include all alternatives, modifications, and equivalents falling within the true spirit and scope of the appended claims.