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

Abstract

The present invention relates to the technical field of oilfield injection and production, and specifically relates to a single-pump same-well injection and production system and its process method. The system adopts a single pump and is equipped with a set of oil production pipelines and a set of separated water reinjection pipelines, which can freely switch between oil production operations and water injection operations according to operation needs, and is very flexible and convenient. The requirement for a single machine to drive the pump in the same-well single-pump mode is much lower than that for driving a double pump, which is also the main reason for realizing large-scale promotion. In addition, through the pressure transmission branch and by switching different water distributors, the pressures of different water injection layers can be collected in real time, so as to accurately judge the pressure of stratified water injection, and through the water absorption index of each water injection layer, the water injection volume of different water injection layers can be more accurately determined, realizing precise dynamic adjustment of reinjection.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield injection-production technology, 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 economic and 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 cyclone 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, many deficiencies have also been exposed in the current downhole oil-water separation same-well injection-production technology through on-site tests, mainly in the following aspects:

[0005] In the prior art, the cost of using two pumps in a single well is relatively high, and a large torque is required to drive the two pumps to work simultaneously. The cost to achieve such 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;

[0006] 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 leads to the reinjection layer being injected with water in a general way. To carry out stratified 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, each section should be separated by a packer, and the requirements of the stratified water injection process for pressure-divided water injection should be implemented. Therefore, it is necessary to develop a single-pump same-well injection-production system that can inject water in layers.

[0007] At present, the pipe string mechanism of the stratified water injection system in the experimental stage is relatively cumbersome and cannot meet the requirements of multi-stage fine water injection pursued by oilfield development. This results in the proportion of water absorption thickness of different property oil layers not being able to increase, seriously affecting the swept volume of the injected water. Summary of the Invention

[0008] 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 pipe 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 water injection parameters in real time, control stratified injection parameters, and have an accurate targeted plugging removal effect.

[0009] The technical solution of the present invention is: a single-pump injection-production system for the same well, including an injection-production well string. A plurality of water 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 water injection layer;

[0010] An injection-production pump is arranged 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 arranged on the oil extraction pipeline, and a water extraction valve is arranged on the water extraction pipeline;

[0011] The outlet end of the injection-production pump is respectively connected with a production pipeline pumped out to 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;

[0012] 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.

[0013] 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.

[0014] 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 pumping pipeline.

[0015] Preferably, the water distributor is an electronically controlled water distributor, and the water distributor is electrically connected to the ground controller.

[0016] Preferably, an injection liquid branch extending to the ground is arranged on the pressure transmission branch, and an injection liquid valve is arranged on the injection liquid branch.

[0017] Preferably, an underground oil-water separator is arranged at the bottom of the injection-production well string.

[0018] A single-pump injection-production process method uses the above single-pump injection-production system for the same well;

[0019] 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;

[0020] 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 water 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 injection is carried out to a single-stage water injection layer by opening the switch of a single water distributor, or the position and the water injection volume of the reinjected water are adjusted to a multi-stage water injection layer by opening the switches of a plurality of water distributors.

[0021] 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 drive method of the same well requires much lower single-machine requirements compared to driving a double pump, so the manufacturing and maintenance costs are also much lower. This is also the main reason for the ability to achieve large-scale promotion.

[0022] Through the pressure transmission branch and different water distributors, 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 through the water absorption index of each water injection layer, more accurately determine the water injection volume of different water injection layers. 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.

[0023] The liquid injection branch can be connected to a pump truck, so that the liquid injection branch and the water distributor switch can be used to pump chemicals into different water injection layers. 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. The unblocking agent is injected into the water injection layer that needs to be unblocked through the connection between the ground pump truck and the liquid injection branch, which is more accurate and reliable. In addition, the liquid injection branch can also be used to supplement water into the water injection layer in cooperation with the ground pump truck. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic structural diagram of the present invention;

[0025] 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 INVENTION

[0026] The following further describes the present invention in conjunction with the drawings and embodiments.

[0027] Embodiment 1

[0028] 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. Multiple injection layers are separated by a multi-stage packer 12 arranged vertically on the outer side of the injection-production well string, and a water distributor 13 is connected to the bottom of each stage of the packer 12, so that a water distributor 13 is provided at each injection layer.

[0029] An injection-production pump 9 is provided in the injection-production well string. The inlet end of the injection-production pump 9 is 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.

[0030] The outlet end of the injection-production pump 9 is respectively connected with a production pipeline 1 pumped out of the ground and a reinjection pipeline 7 pumped into the well and connected to 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.

[0031] 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 a pressure detection module 2 is connected through the pressure transmission branch 6. The pressure detection module 2 can be a mechanical pressure gauge or an electronic pressure sensor.

[0032] Embodiment 2

[0033] This embodiment is further optimized on the basis of the above embodiment. Specifically:

[0034] 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.

[0035] Such as Figure 1 , in this embodiment, the pressure detection module 2 is 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.

[0036] In addition, the oil extraction valve 11, the water extraction valve 10, the production valve 5, and the reinjection valve 8 are all 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.

[0037] The switch of the water distributor 13 can be an electrically controlled water distributor 13 that can be electrically connected to the ground controller 18, or a hydraulically driven water distributor 13;

[0038] When the hydraulic-driven water distributor 13 is selected, a hydraulic pump 17 is additionally provided on the ground. The hydraulic outlet of the hydraulic pump 17 is communicated with each water distributor 13 through a pressure injection pipeline 19 respectively. A pressure control valve 20 is provided on each pressure injection pipeline 19 entering the water distributor 13. Both the pressure control valve 20 and the hydraulic pump 17 are electrically connected to the ground controller 18.

[0039] By controlling and starting different pressure control valves 20, the corresponding water distributors 13 are opened for cooperation.

[0040] Embodiment 3

[0041] This embodiment is a process method applying the above single-pump same-well injection-production system, which specifically includes two parts: oil production operation and water injection operation.

[0042] During the 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. The oil in the well is pumped to the ground through the oil extraction pipeline, the injection-production pump 9 and the production pipeline 1 for production.

[0043] During the 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. The water at the bottom of the well is pumped to the water injection layer through the water intake pipeline 16, the injection-production pump 9 and the reinjection pipeline 7.

[0044] The single-pump operation structure is simple and has high stability. A single pump is matched with a group of oil production pipelines 1 and a group of separated water reinjection pipelines 7, and can switch between oil production operation and water injection operation 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 has much lower requirements for the single machine compared with driving a double pump, so the manufacturing and maintenance costs are also much lower. This is also the main reason for realizing large-scale popularization.

[0045] During the 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 the water injection operation can be detected in real time.

[0046] The present invention can collect the pressures of different water injection layers in real time by cooperating with the pressure transmission branch 6 and switching different water distributors 13, 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.

[0047] Furthermore, it can feedback the change of the 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, so as to realize accurate dynamic adjustment of reinjection.

[0048] Embodiment 4

[0049] This embodiment is further optimized on the basis of the above embodiment. Specifically:

[0050] As a preferred embodiment of this example, 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.

[0051] The liquid injection branch 3 can be connected to a pump truck, so that it can pump chemicals into different water injection layers through the cooperation of the liquid injection branch 3 and the opening and closing 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, and the water distributors 13 of other water injection layers can be closed. The unblocking agent is injected into the water injection layer that needs to be unblocked through the ground pump truck connecting to the liquid injection branch 3, which is more accurate and reliable in use. It can also supply water to the water injection layer through the cooperation of the pump truck and the liquid injection branch 3 on the ground.

[0052] The present invention is based on a single pump combined with valve control to form a new process method capable of alternate injection and production. By adjusting the opening and closing of each valve control, it can also achieve real-time monitoring of water injection parameters, control of stratified injection parameters, and has an accurate targeted unblocking effect.

[0053] 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 purpose of the present invention, and the changed content still belongs to the protection scope of the present invention.

Claims

1. Single-pump same-well injection and production system, including injection and production well string, characterized in that: A plurality of water injection layers are separated by a multi-stage packer arranged vertically on the outer side of the injection-production well string, and a water distributor is provided at each water 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 to 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.

2. The single-pump same-well injection and production system according to claim 1, characterized in that: It further includes a ground controller, which can receive the data collected by the pressure detection module and can control the opening and closing of the oil extraction valve, water extraction valve, production valve, reinjection valve and each water distributor.

3. The single-pump same-well injection and production system according to claim 2, wherein: 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 respectively communicated with each water distributor through a pressure injection pipeline, and a pressure control valve is provided on each pressure injection pipeline entering the water distributor. The pressure control valve and the hydraulic pump are both electrically connected to the ground controller.

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

5. The single-pump same-well injection and production system according to claim 1, characterized in that: 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.

6. The single-pump same-well injection and production system according to claim 1, wherein: An underground oil-water separator is provided at the bottom of the injection-production well string.

7. The process method of single-pump injection and production in the same well is characterized in that: The single-pump co-well injection-production system according to any one of claims 1 to 6 is adopted; During 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 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 water 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, water is injected into a single-stage water 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-stage water injection layers by opening the switches of multiple water distributors.

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