# US 10,246,983 B2 · Systems and methods for achieving three-phase separation and core annular flow in pipelines > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,246,983 B2 - Document ID: US10246983B2 - Status: Granted - Kind: B2 - Application number: 15/615,129 - Filed: 2017-06-06 - Published: 2018-02-01 - Granted: 2019-04-02 - Earliest claimed: 2016-07-28 - Assignees: ExxonMobil Upstream Research Company - Applicants: Timothy J. Nedwed; Xiaolei Yin - Inventors: Timothy J. Nedwed; Xiaolei Yin - Web page: https://patentgrep.com/patent/US10246983B2 ## CPC - E21B 43/36: Underwater separating arrangements (E21B43/38 takes precedence) - E21B 43/01: specially adapted for obtaining from underwater installations - F16T 1/00: Steam traps or like apparatus for draining-off liquids from enclosures predominantly containing gases or vapours, e.g. gas lines, steam lines, containers - F17D 1/08: for liquids or viscous products (water-main or service pipe systems E03B7/04; domestic hot-water supply systems F24D17/00) - F17D 3/10: for taking out the product in the line (sampling in general, examining the physical or chemical properties of materials G01N) - F17D 3/14: for eliminating water (separation of liquids B01D, e.g. B01D17/00; separation of gases or vapours B01D53/00) - F22B 37/32: using centrifugal force - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - F16T: STEAM TRAPS OR LIKE APPARATUS FOR DRAINING-OFF LIQUIDS FROM ENCLOSURES PREDOMINANTLY CONTAINING GASES OR VAPOURS - F17D: PIPE-LINE SYSTEMS; PIPE-LINES (pumps or compressors F04; fluid dynamics F15D; valves or the like F16K; pipes, laying pipes, supports, joints, branches, repairing, work on the entire line, accessories F16L; steam traps or the like F16T; fluid-pressure electric cables H01B9/06) - F22B: METHODS OF STEAM GENERATION; STEAM BOILERS ## Abstract A method for the subsea transport of a multi-phase production fluid from a wellhead to a point remote from the wellhead, the multi-phase production fluid comprising a water phase, an oil phase and a gas phase. The method includes introducing the multi-phase production fluid into a pipeline, the pipeline extending from proximate the wellhead to a point remote from the wellhead; imparting rotational motion to the multi-phase production fluid; wherein the rotational motion of the multi-phase production fluid separates the water phase from the oil phase and the gas phase and reduces the pressure drop along the pipeline. A system for the subsea transport of a multi-phase production fluid from a wellhead to a point remote from the wellhead and a method for reducing hydrate formation during the subsea transport of a multi-phase production fluid from a wellhead to a point remote from the wellhead are also provided. ## Claims ### Claim 1 A system for the subsea transport of a multi-phase production fluid from a wellhead to a point remote from the wellhead, the system comprising: a multi-phase production fluid comprising a water phase, an oil phase and a gas phase; a pipeline extending from proximate the wellhead to a point remote from the wellhead, the pipeline structured and arranged to impart rotational motion to the multi-phase production fluid and effective to separate the water phase from the oil phase and the gas phase and reduce the pressure drop along the pipeline, wherein the pipeline is structured and arranged to impart the rotational motion to the multi-phase production fluid; and a core-annular flow within the pipeline comprising a center gas phase, an annulus of the oil phase surrounding the center gas phase, and a thin annulus of the water phase surrounding the annular oil phase; wherein the thin annulus of the water phase is formed between the wall of the pipeline and the annulus of the oil phase within the pipeline, and wherein the thickness of the thin annulus of the water phase is at least 6% of the diameter of the pipeline. ### Claim 2 (depends on 1) The system of claim 1, wherein the rotational motion imparted reduces hydrate formation. ### Claim 3 (depends on 1) The system of claim 1, wherein the rotational motion imparted reduces settling out of precipitated waxes and solids, including produced sand. ### Claim 4 (depends on 1) The system of claim 1, further comprising a plurality of pumping stations positioned along the pipeline to provide additional pressure to maintain flow and phase separation. ### Claim 5 (depends on 1) The system of claim 1, further comprising one or more helical grooves formed along an internal surface of the pipeline to impart rotational motion to the multi-phase fluid. ### Claim 6 (depends on 5) The system of claim 5, wherein the one or more helical grooves are continuous along the length of the pipeline. ### Claim 7 (depends on 1) The system of claim 1, further comprising one or more helical strakes or ribs formed along an internal surface of the pipeline to impart rotational motion to the multi-phase fluid. ### Claim 8 (depends on 7) The system of claim 7, wherein the one or more helical strakes or ribs are continuous along the length of the pipeline. ### Claim 9 (depends on 1) The system of claim 1, further comprising a water inlet tangentially positioned to the flow of the multi-phase production fluid to impart rotational motion. ### Claim 10 (depends on 1) The system of claim 1, further comprising a separation station for separately removing each phase of the multi-phase fluid proximate a processing facility. ### Claim 11 (depends on 1) The system of claim 1, further comprising: a detector to monitor produced water, the produced water comprising water and dissolved gas; and an injector to inject water into the pipeline if the produced water is below a the amount necessary to maintain the minimum thickness of the thin annulus of the water phase. ### Claim 12 (depends on 11) The system of claim 11, wherein the additional water is injected proximate the wellhead. ### Claim 13 (depends on 11) The system of claim 11, wherein the additional water injected reduces the concentration of dissolved gas below a saturation concentration. ### Claim 14 A method for the subsea transport of a multi-phase production fluid from a wellhead to a point remote from the wellhead, the multi-phase production fluid comprising a water phase, an oil phase and a gas phase, the method comprising: introducing the multi-phase production fluid into a pipeline, the pipeline extending from proximate the wellhead to a point remote from the wellhead; and imparting rotational motion to the multi-phase production fluid, wherein the rotational motion of the multi-phase production fluid separates the water phase from the oil phase and the gas phase; creating a core-annular flow within the pipeline comprising a center gas phase, an annulus of the oil phase surrounding the center gas phase, and a thin annulus of the water phase surrounding the annular oil phase; maintaining the thin annulus of the water phase, wherein the thin annulus of the water phase is formed between the wall of the pipeline and the annulus of the oil phase within the pipeline, and wherein the thickness of the thin annulus of the water phase is at least 6% of the diameter of the pipeline. ### Claim 15 (depends on 14) The method of claim 14, further comprising periodically pumping along the pipeline to provide additional pressure to maintain flow and phase separation. ### Claim 16 (depends on 14) The method of claim 14, further comprising separately removing each phase of the multi-phase fluid proximate a processing facility. ### Claim 17 (depends on 14) The method of claim 14, further comprising: monitoring produced water; and if the produced water is below a predetermined level, injecting additional water into the pipeline. ### Claim 18 A method for reducing hydrate formation during the subsea transport of a multi-phase production fluid from a wellhead to a point remote from the wellhead, the method comprising: introducing the multi-phase production fluid into a pipeline, the pipeline extending from proximate the wellhead to a point remote from the wellhead; and imparting rotational motion to the multi-phase production fluid; wherein the rotational motion of the multi-phase production fluid separates the water phase from the oil phase and the gas phase; creating a core-annular flow within the pipeline comprising a center gas phase, an annulus of the oil phase surrounding the center gas phase, and a thin annulus of the water phase surrounding the annulus of the oil phase, wherein the creation of the separated annular phase flow within the pipeline reduces hydrate formation within the pipeline; and maintaining a thin annulus of the water phase, wherein the thin annulus of the water phase is formed between the wall of the pipeline and the annulus of the oil phase within the pipeline, and wherein the thickness of the thin annulus of the water phase is at least 6% of the diameter of the pipeline. ### Claim 19 (depends on 18) The method of claim 18, further comprising: monitoring produced water; and if the produced water is below a the amount necessary to maintain the minimum thickness of the thin annulus of the water phase, injecting additional water into the pipeline. ### Claim 20 (depends on 18) The method of claim 18, further comprising periodically pumping along the pipeline to provide additional pressure to maintain flow and phase separation.