Caisson Two-Phase Emulsion Reducer

• US 20110024124A1
• Filed: 07/31/2009
• Published: 02/03/2011
• Est. Priority Date: 07/31/2009
• Status: Active Grant

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Inventors: Brown, Donn J., Brookbank, Earl B., Bearden, John L.
• Granted Patent: US 8,397,821 B2
• Time in Patent Office: Days
• US Class Current: 166/369
• CPC Class Codes: B01D 19/0021 by bringing the liquid in a thin layer
• CPC Class Codes: B01D 19/0052 in rotating vessels, vessels containing movable parts or in which centrifugal movement is caused B01D19/0026 takes precedence
• CPC Class Codes: E21B 43/128 Adaptation of pump systems with down-hole electric drives
• CPC Class Codes: E21B 43/38 in the well
• CPC Class Codes: F04B 47/00 Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps by using positive or negative pressurised fluid medium acting directly on the liquid to be pumped F04F1/00

Abstract

A seafloor pump assembly is installed within a caisson that has an upper end for receiving a flow of fluid containing gas and liquid. The pump assembly is enclosed within a shroud that has an upper end that seals around the pump assembly and a lower end that is below the motor and is open. A separating device is connected to an upper end portion of the discharge pipe within the caisson. The separating device causes separation of gas from the flow containing gas and liquid to be enhanced prior to the flow reaching the operating liquid level in the caisson.

Claims

1. An apparatus for pumping a fluid containing gas and liquid, the apparatus comprising:

a caisson having an inlet at an upper end for receiving a flow of fluid containing gas and liquid and an outlet at an upper end for discharging gas;

a pump within the caisson for pumping liquid from the caisson;

a liquid discharge pipe extending vertically within the caisson, connected to the pump on a lower end and extending upwardly through the caisson; and

at least one separating device connected to and surrounding the discharge pipe for separating gas from liquid prior to reaching the pump.

2. The apparatus according to claim 1, wherein the separating device is connected to the discharge pipe such that an inner annulus is formed between the discharge pipe and an upper portion of the separating device to allow gas to pass upwardly therethrough and an outer annulus is located between the caisson and the separating device to allow liquid to flow downward past an exterior portion of the separating device.

3. The apparatus according to claim 1, wherein the separating device has a body with a conical portion containing a plurality of apertures located in and extending through the conical portion to allow liquid to pass downwardly therethrough.

4. The apparatus according to claim 1, wherein the separating device has a body with a conical portion containing a plurality of raised vanes positioned along an outer surface of the conical portion, each vane extending helically.

5. The apparatus according to claim 1, wherein the separating device is passive.

6. The apparatus according to claim 1, wherein the at least one separating device comprises a plurality of bodies mounted to the discharge pipe, each of the bodies having a conical portion that extends downward and around a portion of a next lower one of the bodies, defining an annular slot between each of the bodies for admitting gas.

7. The apparatus according to claim 1, further comprising:

a shroud surrounding at least a portion of the pump within the caisson below the separating device, the shroud having an inlet at a lower end for receiving fluid flowing into the caisson.

8. An apparatus for pumping liquid from a subsea caisson having an inlet at an upper end for receiving a flow of fluid containing gas and liquid and an outlet at an upper end for discharging gas, the apparatus comprising:

an electric submersible pump assembly located in the caisson;

a shroud surrounding at least a portion of the pump assembly within the caisson, the shroud having an inlet at a lower end for receiving fluid flowing into the caisson;

a discharge pipe extending vertically within the caisson, connected to the pump assembly and extending upwardly through the caisson; and

at least one passive separating device connected to and surrounding the discharge pipe above the shroud, the separating device having a body with a substantially conical portion extending outward and downward from the discharge pipe, thereby forming an outer annulus between an inner surface of the caisson and an outer surface of the body allowing fluid to pass downwardly therethrough, the body having an open lower end and an upper end that is larger than an outer diameter of the discharge pipe, defining an inner annulus for gas to flow upwardly in the caisson.

9. The apparatus according to claim 8, wherein the at least one separating device comprises a plurality of the bodies, each having a lower end that extends around an upper portion of a next lower one of the bodies, defining an annulus slot to admit gas.

10. The apparatus according to claim 8, wherein the separating device further comprises:

a plurality of apertures located in and extending through the conical portion of the body to allow liquid to pass therethrough.

11. The apparatus according to claim 8, wherein the at least one separating device further comprises:

a plurality of raised vanes positioned along an outer surface of the conical portion of the body, each vane extending helically to thereby create a spiraling effect when the fluid passes over the device.

12. The apparatus according to claim 8, wherein the at least one separating device further comprises:

a cylindrical lower portion joining the conical portion of the body.

13. The apparatus according to claim 8, wherein the separating device comprises:

a plurality of the bodies, each having a cylindrical lower end that extends around the conical portion of a next lower one of the bodies, defining an annulus slot to admit gas into the bodies.

14. The apparatus according to claim 8,

wherein the body of the separating device is mounted to the discharge pipe by a set of spokes.

15. The apparatus according to claim 8, wherein the separation device further comprises:

a plurality of apertures located in and extending through the conical portion of the body to allow liquid to pass therethrough, each of the apertures having an axis parallel with an axis of the body.

16. A method for pumping from a caisson a fluid containing a mixture of liquid and gas flowing into an upper end of the caisson, the method comprising:

(a) suspending a pump assembly within the caisson on a discharge pipe that extends up the caisson;

(b) mounting at least one separating device around the discharge pipe in the caisson above the pump assembly;

(c) flowing a fluid containing a mixture of gas and liquid into an upper end of the caisson;

(c) separating gas from liquid in the fluid with the separating device as the fluid flows downward in the caisson;

(d) allowing the separated gas to flow back upward in the caisson;

(e) allowing the separated liquid to flow downward to an inlet of the pump assembly; and

(f) pumping the liquid through the discharge pipe with the pump assembly.

17. The method of claim 16, wherein step (b) comprises:

mounting the separating device above a liquid level in the caisson; and

step (c) occurs passively without rotating any components of the separating device.

18. The method of claim 16, wherein step (b) comprises:

providing the separating device with a conical portion containing a plurality of raised helical vanes along an outer surface; and

step (c) comprises;

spiraling the fluid thereby further separating a portion of the gas from the fluid.

19. The method of claim 16, wherein step (b) further comprises:

providing a first separation device having a conical body and a plurality of apertures located in and extending through the conical body, and a second separation device with a conical body positioned a distance below and overlapped by the first separation device, defining an annular slot; and

step (c) further comprises;

flowing the fluid over the first separation device and through the apertures in the conical body of the first separation device, thereby further separating a portion of the gas from the fluid mixture; and

flowing the fluid over the second separation device, and inducing gas to flow through the annular slot to further separate a portion of the gas from the fluid.

20. The method of claim 16, wherein step (b) further comprises:

providing the separating device with a body having a conical portion with an upper diameter greater than an outer diameter of the discharge pipe, defining an inner annulus and a lower diameter that is larger than the upper diameter but smaller than an inner diameter of the caisson, defining an outer annulus; and

step (c) comprises;

with the conical portion of the body, impelling the liquid outward to the inner diameter of the caisson and downwardly through the outer annulus, and drawing gas into an open lower end of the body and allowing the gas to flow upwardly through the inner annulus.