WO2014058778A1

WO2014058778A1 - System for downhole and surface multiphase pumping and methods of operation

Info

Publication number: WO2014058778A1
Application number: PCT/US2013/063684
Authority: WO
Inventors: Ramachandran Thazhathe PERINGOD
Original assignee: Shell Oil Company; Shell Internationale Research Maatschappij B.V.
Priority date: 2012-10-09
Filing date: 2013-10-07
Publication date: 2014-04-17

Abstract

A combination downhole and surface level multiphase pumping apparatus and method for lifting extracted materials. Extracted fluids are lifted from wellbore using a hydrocarbon-powered multiphase jet pump. The extracted fluids are pressure treated at surface level, and a portion of them are diverted from collection be reintroduced into the wellbore. The reintroduced hydrocarbon fluids are routed into the downhole hydrocarbon-powered multiphase jet pump so that additional fluids may be extracted.

Description

SYSTEM FOR DOWNHOLE AND SURFACE MULTIPHASE PUMPING AND

METHODS OF OPERATION

FIELD OF THE INVENTION

[0001] The invention relates to lifting fluids from a wellbore by artificial means. Artificial lifting of subterranean fluids is especially important when the borehole includes a dogleg, deep or major deviations, or horizontal segments, or when the produced fluids have a high g content, and/or variable properties.

BACKGROUND OF THE INVENTION

[0002] In some drilling operations for the extraction of energy resources, unexpected complications may hinder the ability to extract subterranean resources such as oil and gas. For example, wells with severe doglegs, major deviations, deep horizontal segments, high gas content, and unpredictable performance are situations that will impede the equipment' s extraction of resources.

[0003] Limited options currently exist for mitigating or solving these problems. One method of extraction, hydraulic jet pumping, is uncommon despite being known in the art because of its disadvantages. One disadvantage of hydraulic jet pumping is the greater footprint caused by the operation. Another problem with this approach is that it requires a power fluid, commonly water, which increases tube corrosion because carbon dioxide is frequently present in the fluids produced from pumping.

[0004] A second method for extracting resources in this situation is downhole multiphase pumping technology, but its usefulness is also limited. When a wellbore includes a deviation or severe dogleg, the long-term use of a downhole pump is nearly impossible.

[0005] Thus, known technologies provide only limited solutions to a major and complex problem in hydrocarbon production . Oil and gas are expected to remain as primary energy sources well into the foreseeable future, and demand for energy is expected to increase rapidly. Initiating new extraction operations is also difficult, expensive, and time consuming. Technology for efficient use of present drilling operations is thus a valuable and necessary frontier for driving sustainable extraction of oil and gas. SUMMARY OF THE INVENTION

[0006] It is an object of the invention to provide a combination downhole and surface system and process for multiphase pumping of oil and gas that avoid the disadvantages associated with existing technologies.

[0007] It is a further object of the invention to provide an improvement to existing jet pumping systems that makes efficient use of available resources and minimizes collateral damage to the drill string and equipment housed inside a wellbore.

[0008] It is another object of the invention to use wellbore fluids in lieu of a conventional power fluid to perform jet pumping to decrease the surface footprint and avoid issues of incompatibility.

[0009] It is yet a further object of this invention to lift subsurface hydrocarbons to the surface through a jet pump powered by previously-extracted fluids, and to further pass the extracted hydrocarbons with a surface multiphase pump or wellhead compression system. The surface multiphase pump and wellhead compression systems offer surface accessible alternatives to the existing wellbore-installed pumps and compressors.

[0010] In wellbore with high gas content, adding a downhole gas separator offers additional advantages. Generally, a subsurface pump is sufficient to life extracted hydrocarbons to the surface. However, in situations where a significant portion of the hydrocarbons comprise gas, the addition of a downhole gas separator allows gas to be extracted and lifted through a casing line. The subsurface pump will then be applied only to the non-separated hydrocarbons for greater efficiency.

[0011] Preferred embodiments of the invention include two methods for supplementing energy to the production stream using surface or wellhead installations. By one method, fluids at surface level enter a multiphase pump and, through a booster, reach a higher pressure and may be injected back into the wellbore through a multiphase downhole jet pump. By a second, similar method, a stream of discharge enters a wellhead compression system and optional multiphase booster instead of a surface level multiphase pump. In the compression system and optional booster, the liquid's pressure increases and is injected into a downhole multiphase jet pump. This optional booster may be an ESP, gas compressor, or multiphase booster pump depending on the nature of the treated fluid. This second allows for both gas liquids to be diverted for reuse as a power fluid. [0012] As used in this specification and claims the following terms shall have the following meanings:

[0013] "Dogleg" refers to a crooked location in wellbore where the wellbore experiences a relatively abrupt change in trajectory.

[0014] "Downhole" refers to a location inside wellbore as opposed to a location at earth's surface.

[0015] "Electric Submersible Pump" or "ESP" refers to a downhole electric pump designed to avoid losses caused by friction in oil viscosity

[0016] "Multiphase" refers to a composite fluid containing two or more of oil, water, gas, or other immiscible fluids.

[0017] "Wellhead" refers to the surface termination of wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a more detailed understanding of the invention, reference is made to the accompanying wherein:

[0019] Figure 1 is a schematic of one embodiment of the invention, displaying the process by which oil, gas, and water are artificially lifted from wellbore.

[0020] Figure 2 is a cyclical flowchart of a method for using the disclosed invention. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0021] Referring to Figure 1, a first embodiment of the invention includes equipment for providing artificial lift of resources such as oil and gas installed within and above a wellbore 502, which may be linked to other wells 504 by a wellhead pad 506. Materials and resources extracted from wellbore 502 and wells 504 are connected by pipeline or similar delivery system to a central processing facility 500. Components of the present system may be installed on both wellhead pad 506 and within wellbore 502.

[0022] Wellbore 502 is located beneath the earth's surface to extract fluids 10 such as subsurface oil, gas, and water. According to the invention, fluids 10 enter wellbore 502 through perforations in the casing. In some cases, fluids 10 are pumped directly from wellbore 502. When fluids 10 include high gas content, they are preferably processed in a downhole gas separator 100, which separates produced gas from other fluids before they are pumped out of wellbore 502. In this situation, gas separated by downhole separator 100 enters a production line, which for greater efficiency may be the same line used for tubing operations. Liquids exiting separator 100 enter a downhole jet pump 102 powered by power fluids 12 obtained from previously extracted fluids 10. The fluids 10 are thus pumped from wellbore 502 to wellhead pad 506 at the surface.

[0023] The ability to use surface components to power downhole jet pump 102 may be achieved by at least two equipment assemblies. In one assembly, extracted fluids enter a multiphase pump 104 and may also have been processed by a downhole gas separator 100. Including downhole gas separator 100 is preferable when fluid 10 has high gas content, but fluid 10 may be passed through multiphase pump 104 regardless of whether it includes gas. Multiphase pump 104 boosts the pressure of liquids, i.e. oil and water from produced fluids 10 before transmission to central processing facility 500. The presence of multiphase pump 104 at the surface offers the advantages of greater accessibility and lower energy cost when fluids 10 have high gas content because gas was previously removed from fluid 10 by gas separator 100, decreasing the gas volume fraction of fluid 10. Low pressure fluids with a low gas volume fraction are more efficient for pressure boosting since less energy must be diverted to increase the pressure of the gas.

[0024] In this first assembly, a portion of fluid 10 leaving multiphase pump 104 is removed from the stream to eventually be used as high pressure power fluid 12 for downhole jet pump 102. The removed portion of fluid 10 preferably enters an in-line strainer 108 to remove any solids that are unnecessary and potentially harmful to downhole jet pump 102. If required, inhibitors 14 such as wax, asphaltene, corrosion inhibitor, scale inhibitor, or paraffin inhibitor may be added to the jetting stream after leaving strainer 108. The fluid thus becomes a high pressure power fluid 12 and returns to wellbore 502 to power jet pump 102, which lifts new fluid 10 to wellhead pad 506.

[0025] A second equipment assembly embodying the disclosed invention is also available. A wellhead compression system (not shown) may be used in lieu of multiphase pump 104 when fluid 10 exits wellbore 502. When a wellhead compression system is provided , pressurized compressed fluid 12 is either delivered to central processing facility 500 and/or a separate stream for re-entry into wellbore 502.

[0026] In some embodiments, this separate stream of fluid 12 for re-entry into wellbore 502 enters an optional booster 110, which further increases the pressure of fluid 10 before its reintroduction to wellbore 502. Inhibitors 14, when necessary, may be introduced into fluid 10 before reaching optional booster 110 in this configuration. Optional booster 110 may be a surface ESP, and an in-line strainer 108 may be installed to remove solid materials from fluid 10. For multiphase streams of fluid, the user may install a multiphase booster pump as optional pressure booster 110. If the system uses a stream of gas for re-entry into wellbore 502, optional booster 110 may take the form of a gas compressor. Following the applicable treatment, fluid 10 becomes a high pressure power fluid 12 which reenters wellbore 502 to power downhole jet pump 102.

[0027] Turning to Fig. 2, the processes for using this embodiment of the invention will now be described. In preferred embodiments, the invention includes a cyclical method for extracting hydrocarbon fluids such as oil and gas to be powered by the partial diversion of the same hydrocarbon fluids extracted from wellbore. First, hydrocarbon fluids such as oil, gas and water are extracted 1000 from wellbore and gas may be separated 1002 from other fluids when a high percentage of gas exists. After the optional separation, the system lifts gas to the surface of the well through a separate production line, and can be diverted into an existing tubing line. Meanwhile, fluids are pumped 1004 through a downhole jet pump which uses diverted and processed hydrocarbons, previously extracted by the system, as a power fluid.

[0028] Extracted fluids, upon reaching the wellhead, are converted to higher pressures 1006 through a multiphase pump or a compressor installed at pad level. At this point, the pressurized fluids may enter an in-line strainer for removal 1008 of solid materials from the fluid stream. Extracted hydrocarbons may then be relayed 1010 to a central processing utility, while a portion of the fluid stream is diverted 1012 to be used as power fluid for the downhole jet pump.

[0029] Upon diversion 1012, the system may inject inhibiting chemicals such as wax, asphaltene, corrosion inhibitor, scale inhibitor, etc. as necessary. When the extracted fluid stream was previously compressed at pad level, it may be pressure-boosted 1014 through an optional booster such as a second compressor, multisurface pump, or surface ESP. An ESP is preferable for boosting liquid streams, a pump is preferable for multiphase streams, and a gas compressor is preferable for gas streams.

[0030] Following the diversion and processing of diverted fluid streams, the fluid becomes a source of usable power fluid for a downhole pump. At this point, the new power fluid reenters 1016 the wellbore through a line connected to the downhole pump and allows the pump to perform step 1004. Hence, the diversion of some extracted fluids creates a cyclical and more sustainable process driven by surface-level equipment. Performing the compression and boosting phases at the wellhead pad improves fluid extraction in wells with doglegs and other difficult conditions that hinder the installation of downhole equipment.

[0031] Although the preferred embodiments of the present invention have been described herein, the above description is merely illustrative. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as described by the appended claims.

Claims

C L A I M S

1. An apparatus for extracting subterranean fluids wherein one of a surface level

multiphase pump, booster pump, and wellhead compression system increases the pressure of said extracted subterranean fluids and wherein at least a portion of said extracted subterranean fluids are diverted back into said apparatus to power further extraction of said subterranean fluids.

2. An apparatus for extracting fluids from a wellbore, comprising: a fluid-pressure-powered jet pump located in said wellbore;

a wellhead pad at the surface and in fluid communication with said wellbore; a pressurizing device receiving fluids from said wellbore wherein said pressurizing device converts fluids into a pressurized fluid; and,

an injection line wherein said pressurized fluid returns through said injection line to said fluid-pressure-powered jet pump from said wellhead.

3. The apparatus of claim 2 wherein a central processing facility receives hydrocarbon fluid from said pressurizing device.

4. The apparatus of claim 2 wherein a gas separator is disposed in said wellbore blow said fluid-pressure-powered jet pump.

5. The apparatus of claim 2 wherein said pressurizing device comprises at least one of a surface multiphase pump, booster pump, and gas compressor.

6. The apparatus of claim 2, further comprising a strainer disposed on said wellhead pad and operatively connected to said pressurizing device wherein said strainer removes a plurality of solid materials from said hydrocarbon fluid.

7. The apparatus of claim 2 wherein a booster is disposed between said pressurizing device and said injection line.

8. The apparatus of claim 7 wherein said booster comprises one of a multiphase pump, electric submersible pump, and gas compressor.

9. The apparatus of claim 2 wherein an inhibitor injection line communicates with said hydrocarbon fluid between said pressurizing device and said injection line.

10. The apparatus of claim 9 wherein said inhibitor injection line introduces at least one wax, asphaltene, corrosion inhibitor, and scale inhibitor, and paraffin inhibitor into said hydrocarbon fluid.

11. The apparatus of claim 2 wherein said wellhead pad is connected to a plurality of wellbores.

12. The apparatus of claim 11 wherein said plurality of wellbores each have a

hydrocarbon-powered jet pump.

13. A method for powering fluid from a wellbore, comprising:

a) providing hydrocarbon fluids extracted from a wellbore through operation of a hydrocarbon-powered jet pump;

b) increasing the pressure of said extracted hydrocarbon fluids through use of at least one surface-level pressurizing device so as yield pressurized fluids;

c) diverting at least a portion of said pressurized fluids into said wellbore; and d) using said diverted pressurized fluids to power said hydrocarbon-powered jet pump.

14. The method of claim 13 further comprising the additional step of separating, with a gas separator, gas from said hydrocarbon fluids before extracting said hydrocarbon fluids with said hydrocarbon-powered jet pump.

15. The method of claim 14 further comprising the additional step of diverting said extracted gas into a tubing production line.

16. The method of claim 13, further comprising the additional step of straining a plurality of solid matter from said extracted hydrocarbon fluids after extracting said hydrocarbon fluids from said wellbore.

17. The method of claim 13, further comprising the additional step of introducing at least one of wax, asphaltene, corrosion inhibitor, and scale inhibitor, and paraffin inhibitor.

18. The method of claim 13 wherein said at least one surface-level pressurizing device comprises one of a surface multiphase pump and booster pump.

19. The method of claim 18, further comprising the additional step of increasing the pressure of said hydrocarbon fluids by treating said hydrocarbon fluids with a booster device.

20. The method of claim 19 wherein said booster device comprises one of a surface-level electric submersible pump, gas compressor, and multiphase booster pump.