Downhole oil-water separation testing, adjusting, reinjection, plug removal and flowback process pipe column

Abstract

The invention discloses an underground oil-water separation testing, adjusting, reinjection, plug removal and flowback process pipe column. Comprising a sleeve, a flowback plug, and a pipe with a hole, an insertion seal, a positioning bypass device, an annular check valve, a reinjection oil pipe, a central measuring and adjusting working barrel, an annular measuring and adjusting working barrel, a suspension type separator and a lifting oil pipe which are sequentially arranged and connected from bottom to top, the positioning bypass device and the annulus check valve are provided with channels allowing produced liquid, reinjection liquid and flowback liquid to pass through, and an annulus water nozzle is installed on the annulus type measuring and adjusting working barrel and can be opened or closed under regulation and control of a measuring and adjusting instrument. The annulus type measuring and adjusting working barrel and the center type measuring and adjusting working barrel are arranged on a reinjection channel, opening and closing and the opening degree of a water nozzle are adjusted and controlled through a measuring and adjusting instrument, and the functions of underground oil-water separation reinjection water monitoring and adjusting and well washing flowback switching can be achieved; and the problem of reinjection blockage caused by siltation in a near wellbore area is relieved.

Description

Technical Field

[0001] The invention relates to the technical field of oil-water separation pipe string, in particular to a downhole oil-water separation measurement, adjustment, injection, plugging and backflow process pipe string. Background Art

[0002] With the continuous exploitation of offshore oil fields, the problem of high water content in production oil fields has become increasingly severe, and various forms of water control technologies have emerged. Among them, downhole oil-water separation technology has received widespread attention and research. In recent years, a lot of useful work has been done at home and abroad in the upgrading and improvement of downhole oil-water separators, which has greatly improved the separation efficiency of oil-water separators, effectively solving the problem of downhole oil-water separation and production, and reducing the ground water content; but reinjection after downhole separation always faces many problems. Since the suspended matter and oil content of low-oil wastewater are higher than the required indicators, it is easy to cause siltation in the near-well area after reinjection into the injection layer, causing reinjection blockage, resulting in continuous increase in injection pressure, reduction in diversion ratio, and decrease in separation efficiency, affecting the downhole oil-water separation effect and overall economic benefits. This is also one of the main reasons why the promotion and application of downhole oil-water separation and reinjection technology are limited.

[0003] Therefore, a new downhole oil-water separation, measurement, adjustment, injection, plugging and return process string is urgently needed to solve the above technical problems. Summary of the invention

[0004] The present invention aims to solve the above-mentioned technical problem, that is, to solve the problem that the low-oil-containing wastewater that is reinjected after the existing downhole oil-water separation contains suspended matter and oil content that are higher than the required indicators, so it is easy to cause siltation in the near-well area after reinjection into the injection layer, resulting in reinjection blockage, thereby causing the injection pressure to continue to increase, the diversion ratio to decrease, the separation efficiency to decrease, and the downhole oil-water separation effect and the overall economic benefits to be affected.

[0005] To this end, the present invention provides a downhole oil-water separation measurement, adjustment, reinjection, unblocking and return flow process pipe column, including casing, return flow plug and a perforated pipe arranged inside the casing and arranged in sequence from bottom to top, an insert seal, a positioning bypass, an annulus check valve, a return oil pipe, a central measurement and adjustment working cylinder, an annulus measurement and adjustment working cylinder, a suspended separator and a lifting oil pipe. The positioning bypass and the annulus check valve are provided with channels that can allow production fluid, reinjection fluid and return flow fluid to pass through. The channel for passing production fluid on the annulus check valve is a one-way channel. An annulus water nozzle is installed on the annulus measurement and adjustment working cylinder. The annulus water nozzle can be opened or closed under the control of the measurement and adjustment instrument to make the annulus measurement and adjustment working cylinder and the casing annulus connected or disconnected with each other. The return flow plug is lowered into the channel on the suspended separator for reinjection of reinjection water when performing the unblocking and return flow operation.

[0006] In the specific implementation of the downhole oil-water separation measurement, adjustment, injection, plugging and flowback process string, a central measurement and adjustment working water nozzle is installed inside the central measurement and adjustment working cylinder.

[0007] In the specific implementation of the above-mentioned downhole oil-water separation measurement, adjustment, reinjection, blockage removal and return flow process string, the suspended separator includes a three-way joint, an electric submersible pump unit and an oil-water separator. The top of the three-way joint is provided with an oil outlet, and the oil outlet is connected to the lifting oil pipe. The bottom end of the three-way joint is provided with a production liquid inlet and a reinjection liquid outlet. The oil-water separator is installed at the production liquid inlet, and the inlet of the oil-water separator is installed with the electric submersible pump unit, and the reinjection liquid outlet is connected to the annular measurement and adjustment working cylinder.

[0008] In the specific implementation of the downhole oil-water separation, measurement, adjustment, reinjection, blockage removal and backflow process string, a sampling joint is connected between the reinjection fluid outlet and the annular measurement and adjustment working cylinder, and a sampling pipeline is connected to the sampling joint.

[0009] In the specific implementation of the above-mentioned downhole oil-water separation measurement, adjustment, injection, unblocking and return flow process tubing string, the positioning bypass device includes a positioning plate and a first reinjection and return flow channel that can allow the return fluid of the reinjection fluid and the water injection layer to pass through when the return fluid is returned, one end of the first reinjection and return flow channel is connected to the inserted seal, and the other end of the first reinjection and return flow channel is connected to the annulus current valve, the positioning plate is fixed on the outer peripheral wall of the first reinjection and return flow channel in a sleeve manner, the positioning plate cooperates with the first sealer arranged between the liquid producing layer and the casing annulus to achieve position positioning and sealing, and the positioning plate is provided with a bypass channel for allowing the production fluid produced by the liquid producing layer to pass through.

[0010] In the specific implementation of the above-mentioned downhole oil-water separation measurement, adjustment, reinjection, unblocking and return flow process tubing string, the annulus check valve includes an annular disk and a second reinjection return flow channel that can allow the return fluid of the reinjection fluid and the water injection layer to pass through, one end of the second reinjection return flow channel is fixedly connected to the other end of the first reinjection return flow channel, and the other end of the second reinjection return flow channel is fixedly connected to the reinjection oil pipe, the annular disk is fixed on the outer peripheral wall of the second reinjection return flow channel in a sleeve manner, and a one-way valve is installed on the annular disk to form a one-way channel to pass the liquid flowing through the bypass channel.

[0011] In the specific implementation of the above-mentioned downhole oil-water separation, measurement, adjustment, injection, plugging and return flow process string, the inserted seal is inserted on the second packer located in the casing between the liquid production layer and the water injection layer, and a cable packer is also arranged in the casing.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention arranges an annular measuring and adjusting working cylinder with an annular water nozzle and a central measuring and adjusting working cylinder with a central measuring and adjusting working water nozzle on the reinjection channel. The opening and closing and the opening degree of the water nozzle are adjusted by carrying a measuring and adjusting instrument through a ground cable, so that the monitoring and control of the reinjection water for downhole oil-water separation and the switching function of the well washing and return flow can be realized. The pipe string structure is simple, and the reinjection water control and return flow functions are safe, timely and reliable. Since the unblocking and return flow operation can be carried out regularly, the problem of reinjection blockage caused by siltation in the near-well area is alleviated, the life of the reinjection water for downhole oil-water separation is prolonged, which is beneficial to improving the downhole oil-water separation effect and the overall economic benefit.

[0013] 2. The annular check valve provided in the present invention includes liquid that is only allowed to pass through the bypass channel on the positioning bypass device. During the flowback process, it can not only make the oil-water separation production channel and the production layer flowback channel the same, but also ensure that the flowback liquid will not flow back into the liquid production layer during the flowback process, which is beneficial to ensuring the quality of the produced liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings, in which: Figure 1 It is a structural schematic diagram of the downhole oil-water separation, measurement, adjustment, injection, plugging and backflow process string provided by the present invention; Figure 2 yes Figure 1 Schematic diagram of the production layer return channel C and the injection layer return channel D during unblocking and return flow.

[0015] List of reference numerals: 1. Casing; 2. Perforated pipe; 3. Insert seal; 4. Positioning bypass; 4-1. Positioning disk; 4-2. First reinjection and return flow channel; 4-3. Bypass channel; 5. Annular check valve; 5-1. Second reinjection and return flow channel; 5-2. Annular disk; 6. Reinjection oil pipe; 7. Central type measuring and adjusting working cylinder; 7-1. Central type measuring and adjusting working water nozzle; 8. Annular type measuring and adjusting working cylinder; 8-1. Annular water nozzle; 9. Sampling joint; 10. Suspended separator; 10-1. Oil outlet; 10-2. Reinjection liquid outlet; 11. Lifting oil pipe; 12. Cable packer; 13. Oil-water separator; 14. Submersible pump unit; 15. Power cable; 16. Sampling pipeline; 17. Return flow plug; 18. First packer; 19. Second packer. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0017] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the system or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are used to define components, only for the convenience of distinguishing the above components, and unless otherwise stated, the above terms have no special meanings and cannot be understood as indicating or implying relative importance.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "setting", and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] The present invention relates to the technical field of oil-water separation pipe string, and in particular to a downhole oil-water separation measurement, adjustment, injection, plugging and backflow process pipe string. The purpose is to solve the problem that the low-oil-containing sewage injected after the existing downhole oil-water separation contains suspended matter and oil content higher than the required index, so it is easy to cause siltation in the near-well area after the injection layer, resulting in injection blockage, thereby causing the injection pressure to continue to increase, the diversion ratio to decrease, the separation efficiency to decrease, and the downhole oil-water separation effect and overall economic benefits to be affected. To this end, the present invention provides a downhole oil-water separation, measurement, adjustment, injection, unblocking and return flow process column, including casing, return flow plug and a perforated pipe arranged inside the casing and connected in sequence from bottom to top, an insert seal, a positioning bypass, an annulus check valve, a return oil pipe, a central measurement and adjustment working cylinder, an annulus measurement and adjustment working cylinder, a suspended separator and a lifting oil pipe. The positioning bypass and the annulus check valve are provided with channels through which production fluid, return injection fluid and return flow fluid can pass. The channel for production fluid on the annulus check valve is a one-way channel. An annulus measurement and adjustment working cylinder is equipped with an annulus water nozzle, which can be opened or closed under the control of the measurement and adjustment instrument to allow the annulus measurement and adjustment working cylinder to pass through. The return plug is connected or not connected with the casing annulus, and is lowered into the channel for reinjection of reinjection water on the suspended separator when performing unblocking and return operation. The present invention provides an annular measuring and adjusting working cylinder with an annular water nozzle and a central measuring and adjusting working cylinder with a central measuring and adjusting working water nozzle on the reinjection channel. The opening and closing and the opening degree of the water nozzle are regulated by carrying a measuring and adjusting instrument through a ground cable, so that the downhole oil-water separation return water monitoring and regulation and the well washing and return switching functions can be realized. The tubing string has a simple structure, and the return water regulation and return function operations are safe, timely and reliable. Since the unblocking and return operation can be performed regularly, the problem of return injection blockage caused by siltation in the near-well area is alleviated.

[0020] Next, the downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string provided by the embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0021] See also Figure 1-2The present invention provides a downhole oil-water separation, measurement, adjustment, injection, plugging and backflow process string, comprising a casing 1, a backflow plug 17, and a perforated pipe 2, an insert seal 3, a positioning bypass 4, an annular check valve 5, a backflow oil pipe 6, a central measurement and adjustment working cylinder 7, an annular measurement and adjustment working cylinder 8, a hanging separator 10 and a lifting oil pipe 11. The positioning bypass 4 and the annular check valve 5 are provided with channels that can allow production fluid, backflow fluid and backflow fluid to pass through. The channel on the annular check valve 5 for passing the produced liquid is a one-way channel. An annular water nozzle 8-1 is installed on the annular measuring and adjusting working cylinder 8. The annular water nozzle 8-1 can be opened or closed under the control of the measuring and adjusting instrument to make the annular measuring and adjusting working cylinder 8 and the casing annulus connected or disconnected with each other. The return plug 17 is lowered into the channel for reinjection of reinjection water on the suspended separator 10 when performing the unblocking and return operation. A central measuring and adjusting working water nozzle 7-1 is installed inside the central measuring and adjusting working cylinder 7.

[0022] Specifically, the insert seal 3 is inserted into the second packer 19 between the liquid production layer and the water injection layer in the casing 1. The casing 1 is also provided with a cable packer 12 for passing the cable and ensuring that the casing annulus is in a closed state. The lifting tubing 11 passes through the cable packer 12. The casing 1 is also provided with a power cable 15 matched with the pipe string, and the power cable 15 can provide power to the electric submersible pump unit 14.

[0023] During flowback, when the wellhead cable operation carries the measuring and adjusting instrument to open the annular water nozzle 8-1, the annular measuring and adjusting working tube is connected with the casing annulus. During oil-water separation production, the annular water nozzle 8-1 is in a closed state, at which time the annular measuring and adjusting working tube is not connected with the casing annulus, and the reinjection fluid flows from the annular measuring and adjusting working tube into the central measuring and adjusting working tube 7, and then flows to the water injection layer through the reinjection oil pipe.

[0024] More specifically, the suspended separator 10 includes a three-way joint, an electric submersible pump unit 14 and an oil-water separator 13. The top of the three-way joint is provided with an oil outlet 10-1, and the oil outlet 10-1 is connected to the lifting oil pipe 11. The bottom of the three-way joint is provided with a production liquid inlet and a reinjection liquid outlet 10-2. The production liquid inlet is equipped with an oil-water separator 13, and the inlet of the oil-water separator 13 is equipped with an electric submersible pump unit 14. The reinjection liquid outlet 10-2 is connected to the annular measuring and adjusting working cylinder 8.

[0025] In one embodiment, a sampling joint 9 is connected between the reinjection liquid outlet 10-2 and the annular measuring and adjusting mandrel 8, and a sampling pipeline 16 is connected to the sampling joint 9. The sampling is used to test the oil content in the reinjection water after separation.

[0026] In one embodiment, the positioning bypass device 4 includes a positioning plate 4-1 and a first reinjection return flow channel 4-2 that allows the return flow of the reinjection fluid and the water injection layer to pass through. One end of the first reinjection return flow channel 4-2 is connected to the insert seal 3, and the other end of the first reinjection return flow channel 4-2 is connected to the annular current valve. The positioning plate 4-1 is fixed on the outer peripheral wall of the first reinjection return flow channel 4-2 in a sleeve manner. The positioning plate 4-1 cooperates with the first packer 18 arranged between the liquid production layer and the casing annulus to achieve position positioning and sealing. The positioning plate 4-1 is provided with a bypass channel 4-3 for the production of the liquid production layer. The first packer 18 is used to separate the liquid production layer from the casing annulus. The bottom end of the positioning plate 4-1 is inserted into the first packer 18 and tightly fitted to achieve sealing, so that the production of the liquid production layer can only flow into the casing annulus through the bypass channel 4-3 and the annular check valve 5.

[0027] In one embodiment, the annular check valve 5 includes an annular disc 5-2 and a second reinjection return channel 5-1 that allows the return fluid and the return fluid of the water injection layer to pass through. One end of the second reinjection return channel 5-1 is fixedly connected to the other end of the first reinjection return channel 4-2, and the other end of the second reinjection return channel 5-1 is fixedly connected to the return oil pipe 6, so that the first reinjection return channel 4-2 is connected to the return oil pipe 6 through the second reinjection return channel 5-1. The annular disc 5-2 is fixed on the outer peripheral wall of the second reinjection return channel 5-1 in a sleeve manner. A check valve is installed on the annular disc 5-2 to form a one-way channel to pass the liquid flowing through the bypass channel 4-3. The liquid can be the production liquid or the return liquid returned from the production layer during the return. Due to the setting of the check valve, the production liquid can only enter the casing annulus from the bypass channel 4-3, and the liquid in the casing annulus cannot flow into the casing 1 connected to the production layer.

[0028] In addition, the first packer 18 and the second packer 19 are connected by a screen pipe, and the screen pipe is arranged in the casing 1. The produced liquid of the liquid producing layer flows to the bypass channel 4-3 through the screen pipe, and the reinjection liquid is reinjected into the water injection layer through the screen pipe. This part of the content is the existing technology for those skilled in the art, so it will not be elaborated here.

[0029] like Figure 1-2As shown, the underground oil-water separation production is divided into oil-water separation production channel A and measurement and adjustment reinjection channel B. The oil-water separation production channel A is composed of the liquid production layer, the positioning bypass device 4, the annular check valve 5, the electric submersible pump unit 14, the oil-water separator 13, the oil outlet 10-1 of the hanging separator to the lifting oil pipe 11; the measurement and adjustment reinjection channel B is the reinjection liquid outlet 10-2 of the hanging separator, the sampling joint 9, the annular measurement and adjustment working cylinder 8, the central measurement and adjustment working cylinder 7, the reinjection oil pipe 6, the perforated pipe 2 to the water injection layer; the reinjection water blockage relief backflow is divided into the production layer backflow channel C and the water injection layer backflow channel D. The annular check valve 5 is provided to ensure that the direction of the production layer return flow channel C is the same as that of the production channel A; the water injection layer return flow channel D is from the water injection layer, the perforated pipe 2, the return oil pipe 6, the central measuring and adjusting working cylinder, the annular water nozzle on the annular measuring and adjusting working cylinder, the electric submersible pump unit 14, the oil-water separator 13, the oil outlet 10-1 of the suspended separator to the lifting oil pipe.

[0030] Working principle of the present invention: When the downhole oil-water separation is in normal production: the annular water nozzle 8-1 on the annular measuring and adjusting working tube 8 is closed by the measuring and adjusting instrument, the produced liquid is lifted by the electric submersible pump unit 14 and separated by the oil-water separator 13, and the oil-rich produced liquid is lifted to the surface through the upper lifting oil pipe 11, such as Figure 1 As shown in the oil-water separation production channel A; low oil content reinjection water is reinjected into the water injection layer through the reinjection oil pipe 6; the measuring and adjusting instrument is lowered through cable operation to monitor the reinjection water parameters, and the central measuring and adjusting working water nozzle 7-1 on the central measuring and adjusting working cylinder 7 is adjusted to adjust the water injection volume. When backflow is performed: the measuring and adjusting instrument is lowered to open the annular water nozzle 8-1 of the annular measuring and adjusting working cylinder, and the backflow plug 17 is placed in the suspended separator. The oil-producing layer backflow channel C is the same as the production channel A; the water in the water injection layer enters the casing annulus through the reinjection oil pipe 6, the central measuring and adjusting working cylinder 7, and the annular water nozzle 8-1 on the annular measuring and adjusting working cylinder, and is lifted to the ground through the electric submersible pump unit 14 and the lifting oil pipe 11 to complete the backflow.

[0031] The channel for unblocking and returning flow designed in the present invention can alleviate the problem of reinjection blockage caused by siltation in the near-well area due to reinjection by regularly performing unblocking and returning flow operations, thereby delaying the life of the underground oil-water separation reinjection water, which is beneficial to improving the underground oil-water separation effect and the overall economic benefits.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A downhole oil-water separation, measurement, adjustment, injection, plugging and backflow process string, characterized in that: It includes casing, backflow plug, and a perforated pipe arranged inside the casing and connected in sequence from bottom to top, an insert seal, a positioning bypass, an annulus check valve, a reinjection oil pipe, a central measuring and adjusting working cylinder, an annulus measuring and adjusting working cylinder, a suspended separator and a lifting oil pipe. The positioning bypass and the annulus check valve are provided with channels that can allow production fluid, reinjection fluid and backflow fluid to pass through. The channel for production fluid on the annulus check valve is a one-way channel. An annulus water nozzle is installed on the annulus measuring and adjusting working cylinder. The annulus water nozzle can be opened or closed under the control of the measuring and adjusting instrument to make the annulus measuring and adjusting working cylinder and the casing annulus connected or disconnected with each other. The backflow plug is lowered into the channel on the suspended separator for reinjection of reinjection water when performing an unblocking and backflow operation.

2. The downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string according to claim 1 is characterized in that: A central-type measuring-and-adjusting working water nozzle is installed inside the central-type measuring-and-adjusting working cylinder.

3. The downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string according to claim 1 is characterized in that: The suspended separator includes a three-way joint, an electric submersible pump unit and an oil-water separator. The top of the three-way joint is provided with an oil outlet, and the oil outlet is connected to the lifting oil pipe. The bottom of the three-way joint is provided with a production liquid inlet and a reinjection liquid outlet. The oil-water separator is installed at the production liquid inlet, the electric submersible pump unit is installed at the inlet of the oil-water separator, and the reinjection liquid outlet is connected to the annular measuring and adjusting working cylinder.

4. The downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string according to claim 3 is characterized in that: A sampling joint is connected between the reinjection liquid outlet and the annular space-type simultaneous measurement and adjustment working cylinder, and a sampling pipeline is connected to the sampling joint.

5. The downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string according to claim 1, characterized in that: The positioning bypass device includes a positioning plate and a first reinjection return flow channel through which the return fluid of the reinjection fluid and the water injection layer can pass when the return fluid is returned. One end of the first reinjection return flow channel is connected to the inserted seal, and the other end of the first reinjection return flow channel is connected to the annulus current valve. The positioning plate is fixed on the outer peripheral wall of the first reinjection return flow channel in a sleeve manner. The positioning plate cooperates with a first sealer arranged between the liquid producing layer and the casing annulus to achieve position positioning and sealing. The positioning plate is provided with a bypass channel for allowing the produced liquid from the liquid producing layer to pass.

6. The downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string according to claim 5 is characterized in that: The annular check valve includes an annular disk and a second reinjection return flow channel through which the return fluid can pass when the reinjection fluid and the water injection layer are returned. One end of the second reinjection return flow channel is fixedly connected to the other end of the first reinjection return flow channel, and the other end of the second reinjection return flow channel is fixedly connected to the reinjection oil pipe. The annular disk is fixed on the outer peripheral wall of the second reinjection return flow channel in a sleeve manner, and a check valve is installed on the annular disk to form a one-way channel to pass the liquid flowing through the bypass channel.

7. The downhole oil-water separation, measurement, adjustment, injection, plugging and flowback process string according to claim 1, characterized in that: The insert seal is inserted on a second packer located in the casing between the liquid production layer and the water injection layer. A cable packer is also arranged in the casing.

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