Single-pump same-well injection and production system and process method thereof

Abstract

The invention relates to the technical field of oil field injection and production, in particular to a single-pump same-well injection and production system and a process method thereof.The system is matched with a set of oil liquid production pipelines and a set of separated water reinjection pipelines, oil production operation and water injection operation can be freely switched according to operation requirements, and the system is very flexible and convenient; the requirement of a single pump driven by the same-well single pump is much lower than that of a single pump driven by double pumps, which is a main reason for realizing large-scale popularization, in addition, the pressure of different water injection layers can be acquired in real time by matching the pressure transmission branch with different water distributors, so that the pressure of separated layer water injection can be accurately judged, and the requirement of the separated layer water injection is met. And according to the water absorption index of each water injection layer, the water injection amount of different water injection layers is more accurately determined, and accurate dynamic adjustment of reinjection is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield injection-production, and particularly to a single-pump same-well injection-production system and its process method. Background Art

[0002] The same-well injection-production technology is an important technical measure for achieving economically sustainable exploitation in the late stage of extra-high water cut in oilfields.

[0003] The same-well injection-production technology mainly separates the production layer and the reinjection layer through downhole packers to form two independent pressure systems. A production pump and an injection pump are arranged downhole for simultaneous operation of the two pumps. After the high-water-cut produced fluid is separated by sedimentation or swirl separation in the downhole oil-water separator, the low-water-cut fluid is lifted to the ground by the production pump, and the separated water is injected into the reinjection layer after being pressurized by the injection pump. Therefore, the downhole oil-water separation same-well injection-production technology is an important technical means for improving oil recovery and economic benefits in the high water cut period and extra-high water cut period of oilfields.

[0004] However, the current downhole oil-water separation same-well injection-production technology also exposes many deficiencies through on-site tests, mainly in the following aspects: In the prior art, the use of two pumps in a single well has a relatively high cost, and a large torque is required to drive the two pumps to work simultaneously. The cost to achieve such an output capacity is as high as about three hundred thousand, and the power supply and usage cost is also very high. Such a high cost is not conducive to future industrial promotion and application; During on-site application, since the reinjection layer is composed of multiple oil layers with large differences in interlayer permeability, that is, the water absorption capacity of each oil layer is different at the same injection pressure, this results in only general water injection in the reinjection layer. To carry out layered water injection according to the requirements of the oilfield water injection plan, the oilfield water injection plan requires that the reinjection layer should meet three to five sections, and each section should be separated by a packer to meet the requirements of the layered water injection process of pressure-divided water injection. Therefore, it is necessary to develop a single-pump same-well injection-production system that can inject water layer by layer.

[0005] Currently, the string mechanism of the layered water injection system in the experimental stage is relatively cumbersome and cannot meet the requirement of multi-stage fine water injection pursued by oilfield development. This has led to the inability to increase the proportion of the water absorption thickness of oil layers with different properties, seriously affecting the swept volume of the injected water. Summary of the Invention

[0006] The purpose of the present invention is to provide a single-pump same-well injection-production system and its process method in view of the defects existing in the prior art. Based on a single pump and valve control, a new type of process string capable of alternate injection and production is formed. By adjusting the opening and closing of each valve control, it is also possible to monitor the water injection parameters in real time, control the layered injection parameters, and have an accurate targeted plugging removal effect.

[0007] The technical solution of the present invention is: a single-pump injection-production system for the same well, including an injection-production well string. Multiple injection layers are separated by vertically arranged multi-stage packers on the outer side of the injection-production well string, and a water distributor is provided at each injection layer; An injection-production pump is provided in the injection-production well string. The inlet end of the injection-production pump is respectively connected with an oil extraction pipeline and a water extraction pipeline extending into the injection-production well string. An oil extraction valve is provided on the oil extraction pipeline, and a water extraction valve is provided on the water extraction pipeline; The outlet end of the injection-production pump is respectively connected with a production pipeline pumped out of the ground and a reinjection pipeline pumped into the well and connected to each water distributor. A production valve is connected to the production pipeline, and a reinjection valve is connected to the reinjection pipeline; A pressure transmission branch is connected to a part of the reinjection pipeline between the reinjection valve and the water distributor, and a pressure detection module is connected through the pressure transmission branch.

[0008] Preferably, it further includes a ground controller. The ground controller receives the data collected by the pressure detection module, and the ground controller controls the opening and closing of the oil extraction valve, the water extraction valve, the production valve, the reinjection valve and each water distributor.

[0009] Preferably, the water distributor is a hydraulically driven water distributor, and the ground controller is also provided with a hydraulic pump. The outlet of the hydraulic pump is communicated with each water distributor through a pressure boosting pipeline respectively.

[0010] Preferably, the water distributor is an electrically controlled water distributor, and the water distributor is electrically connected to the ground controller.

[0011] Preferably, an injection liquid branch extending to the ground is provided on the pressure transmission branch, and an injection liquid valve is provided on the injection liquid branch.

[0012] Preferably, an underground oil-water separator is provided at the bottom of the injection-production well string.

[0013] A single-pump injection-production process method uses the above single-pump injection-production system for the same well; During the oil production operation: open the oil extraction valve and the production valve, close the water extraction valve and the reinjection valve, and pump the oil liquid to the ground through the oil extraction pipeline, the injection-production pump and the production pipeline; During the water injection operation: open the water extraction valve and the reinjection valve, close the oil extraction valve and the production valve, pump the well water into the injection layer through the water extraction pipeline, the injection-production pump and the reinjection pipeline. During the water injection process, the water injection pressure is detected in real time by the pressure detection module, and according to the change of the water injection pressure, the water is injected into a single-stage injection layer by opening the switch of a single water distributor, or the position and injection volume of the reinjected water are adjusted to multiple injection layers by opening the switches of multiple water distributors.

[0014] Compared with the prior art, the present invention has the following advantages: The present invention adopts a single-pump operation structure, which is simple and has high stability. The single pump is equipped with a set of oil production pipelines and a set of separated water reinjection pipelines, and can switch between oil production operations and water injection operations at will according to operation needs, which is very flexible and convenient. More importantly, the single-pump method for driving the pump in the same well requires much less for a single machine compared to driving a double pump, so the manufacturing and maintenance costs are also much lower, which is also the main reason for enabling large-scale promotion.

[0015] Through the pressure transmission branch and by cooperating with different water distributors, the present invention can collect the pressures of different water injection layers in real time, thereby accurately judging the pressure of layered water injection, and more accurately determining the water injection volume of different water injection layers through the water absorption index of each water injection layer. Furthermore, it can feedback the change of water injection pressure, open the switch of a single water distributor to inject water into a single-stage water injection layer, or open the switches of multiple water distributors to inject water into a multi-stage water injection layer, realizing precise dynamic adjustment of reinjection.

[0016] The liquid injection branch can be connected to a pump truck, so that it can pump agents into different water injection layers in cooperation with the water distributor switch through the liquid injection branch. For example, when a water injection layer with reduced water absorption capacity needs to be unblocked, the water distributor of this water injection layer can be opened, and the water distributors of other water injection layers can be closed, and the plugging removal agent can be injected into the water injection layer that needs to be unblocked by connecting the ground pump truck to the liquid injection branch, which is more precise and reliable. In addition, water can also be replenished into the water injection layer through the liquid injection branch in cooperation with the ground pump truck. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the present invention; In the figure: 1. Production pipeline, 2. Pressure detection module, 3. Liquid injection branch, 4. Liquid injection valve, 5. Production valve, 6. Pressure transmission branch, 7. Reinjection pipeline, 8. Reinjection valve, 9. Injection-production pump, 10. Water intake valve, 11. Oil intake valve, 12. Packer, 13. Water distributor, 14. Downhole oil-water separator, 15. Oil intake pipeline, 16. Water intake pipeline, 17. Hydraulic pump, 18. Ground controller, 19. Pressurization pipeline, 20. Pressure control valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The following further describes the present invention in conjunction with the drawings and embodiments.

[0019] Embodiment 1 As Figure 1 , a single-pump injection-production system in the same well, including an injection-production well string, a downhole oil-water separator 14 is provided at the bottom of the injection-production well string, and multiple water injection layers are separated by a multi-stage packer 12 arranged vertically on the outside of the injection-production well string, and a set of water distributors 13 are connected to the bottom of each stage of the packer 12, so that a water distributor 13 is provided at each water injection layer.

[0020] A injection-production pump 9 is provided inside the injection-production well string. The inlet ends of the injection-production pump 9 are respectively connected with an oil extraction pipeline 15 and a water extraction pipeline 16 extending into the injection-production well string. An oil extraction valve 11 is provided on the oil extraction pipeline 15, and a water extraction valve 10 is provided on the water extraction pipeline 16.

[0021] The outlet ends of the injection-production pump 9 are respectively connected with a production pipeline 1 pumped out to the ground and a reinjection pipeline 7 pumped into the well and connected with each water distributor 13. A production valve 5 is connected to the production pipeline 1, and a reinjection valve 8 is connected to the reinjection pipeline 7.

[0022] A pressure transmission branch 6 is connected to the part of the reinjection pipeline 7 between the reinjection valve 8 and the water distributor 13, and is connected with a pressure detection module 2 through the pressure transmission branch 6. The pressure detection module 2 can be a mechanical pressure gauge or an electronic pressure sensor.

[0023] Embodiment 2 This embodiment is further optimized on the basis of the above embodiment. Specifically: In order to further improve efficiency and perform intelligent control, a ground controller 18 is added in this embodiment. The ground controller 18 can be a PLC controller, an industrial control computer, etc.

[0024] Such as Figure 1 , in this embodiment, the pressure detection module 2 selects an electronic pressure sensor, and the electronic pressure sensor is electrically connected to the ground controller 18, and the data collected by the pressure detection module 2 is received through the ground controller 18.

[0025] In addition, the oil extraction valve 11, the water extraction valve 10, the production valve 5, and the reinjection valve 8 all select electrically controlled valves and are respectively electrically connected to the ground controller 18, and their opening and closing are controlled through the ground controller 18.

[0026] The switch of the water distributor 13 can select an electrically controlled water distributor 13 that can be electrically connected to the ground controller 18, or a hydraulically driven water distributor 13; When the hydraulically driven water distributor 13 is selected, a hydraulic pump 17 is also added on the ground. The hydraulic outlet of the hydraulic pump 17 is respectively communicated with each water distributor 13 through a pressure pumping pipeline 19, and a pressure control valve 20 is provided on each pressure pumping pipeline 19 entering the water distributor 13. The pressure control valve 20 and the hydraulic pump 17 are both electrically connected to the ground controller 18.

[0027] By controlling the start of different pressure control valves 20, the corresponding water distributors 13 are opened.

[0028] Embodiment 3 This embodiment is a process method applying the above single-pump same-well injection-production system, specifically including two parts: oil production operation and water injection operation.

[0029] During oil production operation: Open the oil extraction valve 11 and the production valve 5, close the water intake valve 10 and the reinjection valve 8, and pump the oil in the well to the ground through the oil extraction pipeline, the injection-production pump 9, and the production pipeline 1 for production.

[0030] During water injection operation: Open the water intake valve 10 and the reinjection valve 8, close the oil extraction valve 11 and the production valve 5, and pump the water at the bottom of the well to the water injection layer through the water intake pipeline 16, the injection-production pump 9, and the reinjection pipeline 7.

[0031] The single-pump operation structure is simple and has high stability. A single pump is paired with a group of oil production pipelines 1 and a group of separated water reinjection pipelines 7, which can switch between oil production operation and water injection operation according to operation needs at will, which is very flexible and convenient. More importantly, the single-pump drive of the same well requires much lower single-machine requirements compared to the double-pump drive, so the manufacturing and maintenance costs are also much lower. This is also the main reason for achieving large-scale promotion.

[0032] During water injection operation, by opening different water distributors 13, the pressure of the water injection layer at this place is transmitted to the pressure detection module 2 through the pressure transmission branch 6, and the pressure during water injection operation can be detected in real time.

[0033] Through the cooperation of the pressure transmission branch 6 and the switching of different water distributors 13, the present invention can collect the pressures of different water injection layers in real time, so as to accurately judge the pressure of stratified water injection, and more accurately determine the water injection volume of different water injection layers through the water absorption index of each water injection layer.

[0034] Furthermore, it can feedback the change of water injection pressure, open the switch of a single water distributor 13 to inject water into a single-stage water injection layer, or open the switches of multiple water distributors 13 to inject water into a multi-stage water injection layer, realizing precise dynamic adjustment of reinjection.

[0035] Embodiment 4 This embodiment is further optimized on the basis of the above embodiment. Specifically: As a preferred method of this embodiment, a liquid injection branch 3 extending to the ground is provided on the pressure transmission branch 6, and a liquid injection valve 4 is provided on the liquid injection branch 3.

[0036] The pump truck can be connected through the liquid injection branch 3, so that it can pump chemicals into different water injection layers through the cooperation of the liquid injection branch 3 and the switch of the water distributor 13. For example, when a water injection layer with reduced water absorption capacity needs to be unblocked, the water distributor 13 of this water injection layer can be opened, the water distributors 13 of other water injection layers are closed, and the blocking agent is injected into the water injection layer that needs to be unblocked through the ground pump truck and the liquid injection branch 3. It is more accurate and reliable to use, and water can also be replenished into the water injection layer through the cooperation of the pump truck and the liquid injection branch 3 on the ground.

[0037] The present invention is based on a single pump combined with valve control to form a new process method capable of cyclic injection and production. Moreover, by adjusting the opening and closing of each valve control, it is also possible to realize real-time monitoring of water injection parameters, control layered injection parameters, and have an accurate targeted plugging removal effect.

[0038] The present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the gist of the present invention, and the changed content still falls within the protection scope of the present invention.

Claims

1. A single pump injection-production system in the same well, including an injection-production well string, characterized in that: The outer side of the injection-production well pipe string is separated into multiple water injection layers by vertically arranged multi-stage packers, and a water distributor is provided at each water injection layer; An injection pump is provided in the injection-production well string, and the inlet end of the injection pump is respectively connected to an oil extraction pipeline and a water extraction pipeline extending into the injection-production well string, an oil extraction valve is provided on the oil extraction pipeline, and a water extraction valve is provided on the water extraction pipeline; The outlet ends of the injection pumps are respectively connected to production pipelines pumped out of the ground and reinjection pipelines pumped into the well and connected to various water distributors, the production pipelines are connected to production valves, and the reinjection pipelines are connected to reinjection valves; The portion of the reinjection pipeline between the reinjection valve and the water distributor is connected with a pressure transmission branch, and is connected with a pressure detection module through the pressure transmission branch.

2. The single-pump injection-production system in the same well according to claim 1, characterized in that: It also includes a ground controller, which can receive data collected by the pressure detection module and control the oil extraction valve, water extraction valve, production valve, re-injection valve and the switches of various water distributors.

3. The single-pump injection-production system in the same well according to claim 2, characterized in that: The water distributor is a hydraulically driven water distributor, and a hydraulic pump is also provided on the ground. The hydraulic outlet of the hydraulic pump is connected to each water distributor through a pressure pipeline, and each pressure pipeline entering the water distributor is provided with a pressure control valve. The pressure control valve and the hydraulic pump are electrically connected to the ground controller.

4. The single-pump injection-production system in the same well according to claim 2, characterized in that: The water distributor is an electrically controlled water distributor, and the water distributor is electrically connected to a ground controller.

5. The single-pump same-well injection-production system according to claim 1, characterized in that: The pressure transmission branch is provided with a liquid injection branch extending to the ground, and the liquid injection branch is provided with a liquid injection valve.

6. The single-pump same-well injection-production system according to claim 1, characterized in that: A downhole oil-water separator is provided at the bottom of the injection-production well pipe string.

7. A single-pump injection-production process in the same well, characterized by: A single-pump injection-production system in the same well as claimed in any one of claims 1 to 6; During oil extraction operations: open the oil extraction valve and production valve, close the water extraction valve and re-injection valve, and pump the oil to the surface through the oil extraction pipeline, injection pump and production pipeline; During water injection operation: open the water intake valve and the re-injection valve, close the oil extraction valve and the production valve, pump the water in the well into the injection layer through the water intake pipeline, the injection pump and the re-injection pipeline, and detect the injection pressure in real time through the pressure detection module during the water injection process. According to the changes in the injection pressure, open a single water distributor switch to inject water into a single-stage water injection layer, or open multiple water distributor switches to adjust the position and injection volume of the re-injection water to multiple water injection layers.

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