Downhole oil-water separation multi-layer injection-production process pipe column with step-by-step setting and seal examining functions

Abstract

The invention relates to an underground oil-water separation multi-layer injection-production process pipe column with step-by-step setting and seal examining functions. The problems that an existing injection-production pipe column in the same well cannot be subjected to seal examination after setting, and effective setting cannot be achieved when the number of separation layers is large are mainly solved. The device is characterized in that the lower end of the extraction pump (12) is connected with a pipe column, the pipe column is connected with a plurality of delayed setting packers, the number of the delayed setting packers is the same as that of injection layers, the lower end of the pipe column is connected with an anchoring packer (6), and the water injection layer and the extraction layer are separated by the delayed setting packers and the anchoring packer (6); the injection pump (4) is located below the anchoring packer (6), and the oil-water separator (2) is arranged on the lower portion of the injection pump (4). In the construction process of the underground oil-water separation multi-layer injection-production process pipe column with the step-by-step setting and seal examining functions, step-by-step setting and seal examining can be achieved on the packing pipe column according to process requirements, and it is guaranteed that the injection-production process of the same well is reliably achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil production engineering, and specifically to a downhole oil-water separation multi-layer injection-production process string with step-by-step setting and verification of packers. Background Art

[0002] In the middle and late stages of development of multi-layer oil reservoirs, the water cut in oil wells will become higher and higher, reaching or approaching the economic and technical limits of exploitation, and it is impossible to carry out economic and effective exploitation using conventional oil production technologies. To solve this problem, the same-well injection-production process has been developed. In the production well, the same-well injection-production process string is used to separate oil and water downhole. The separated produced liquid with low water cut is lifted to the ground by a production pump, while the separated water is injected into the injection layer in the same well by an injection pump. This process not only greatly reduces the water cut of the produced liquid at the wellhead of the production well and reduces the production and development costs, but also realizes the dual use of one well, that is, a production well is both an oil production well and an injection well, enabling many high-water-cut wells that cannot be economically and effectively exploited by conventional oil production technologies to regain their vitality and be able to continue economic and effective exploitation for a long time. After implementation in the production well, it can well complete downhole oil-water separation. The oil content of the separated injection water is less than 20 ppm, and the water cut of the separated produced liquid drops below 80%. The dual functions of being both an oil production well and an injection well at the same well point are realized, enabling high-water-cut wells to be economically and effectively developed.

[0003] Currently, the downhole oil-water separation process that has been verified by large-scale field application is the method for realizing the same-well injection-production of high-water-cut wells using the multi-cup equal-flow downhole oil-water separator with the publication number of CN101025080B. When completing the well, the multi-layer gravity setting compression packer process string composed of multiple-stage bridge packers is put into the wellbore at one time together with the oil-water separator and the injection-production pump set, and the one-time setting is realized by the method of pressing the tubing at the wellhead. The following problems are exposed when this process is used for multi-layer staged injection and production in the same well: 1) Due to the shielding problem of the production pump and the sucker rod string, the conventional packer verification technology cannot be applied, and it is impossible to accurately judge whether each stage of the bridge packer is effectively set after setting; 2) In order to ensure that the multi-layer bridge packers can be set simultaneously, it is necessary to apply an additional large axial setting force to the same-well injection-production process string at the wellhead. On average, an additional 2-3 tons of axial setting force is required for each additional stage of the bridge packer. The more the number of separated layers, the greater the required axial setting force, and the large axial setting force will cause the tubing to bend. Even with tubing straightening measures, it is impossible to ensure that the tubing and the rod string are in a reasonable stress state, easily resulting in ineffective setting of the packer and early fatigue damage of the tubing and the rod string. For wells that require downhole oil-water separation injection-production multi-layer separation, limited by the bearing capacity of the injection-production tubing string and the reliability of the packer setting, this process cannot be effectively applied, restricting the application scope of the technology. Summary of the Invention

[0004] In order to overcome the deficiencies that the existing injection-production string in the same well cannot be verified for sealing after setting and cannot be effectively set when there are many separated layers, the present invention provides a downhole oil-water separation multi-layer injection-production process string with step-by-step setting and verification. During the construction process of this downhole oil-water separation multi-layer injection-production process string with step-by-step setting and verification, the packer string can be set and verified step by step according to the process requirements, ensuring the reliable implementation of the injection-production process in the same well.

[0005] The technical solution of the present invention is: a downhole oil-water separation multi-layer injection-production process string with step-by-step setting and verification, including a production pump and an injection pump. The lower end of the production pump is connected to a string, and several delayed setting packers are connected to the string. The number of delayed setting packers is the same as the number of injection layers. The lower end of the string is connected to an anchor packer. The several delayed setting packers and the anchor packer separate the water injection layer and the production layer. The injection pump is located below the anchor packer, and an oil-water separator is provided below the injection pump. The string includes an inner pipe and an outer pipe, and an annular cavity is provided between the inner pipe and the outer pipe. The delayed setting packer includes an injection water nozzle. The inside of the injection water nozzle is communicated with the center of the inner pipe through a water distribution plug, and the outside of the injection water nozzle is communicated with the injection layer. The delayed setting packer is also provided with a flow-through channel, and the flow-through channel is communicated with the oil-water separator and the annular cavity between the inner pipe and the outer pipe, forming a production fluid channel.

[0006] It also includes a special tubing hanger. The special tubing hanger includes a bearing seat. The lower part of the bearing seat is connected to the tubing hanger by bolts. The lower end of the tubing hanger is internally threaded and connected to a center pipe. The lower end of the center pipe is internally connected to a telescopic pipe, and the outside of the lower end of the center pipe is connected to a sealing sleeve. The lower end of the telescopic pipe is connected to the tubing, and the up and down position of the tubing hanger on the string can be adjusted by rotating the bearing seat.

[0007] A bearing nipple passes through the inside of the bearing seat. An external fixed loading crossbeam assembly is provided on the outside of the bearing nipple, and the bottom of the bearing nipple is threadedly connected to the telescopic pipe.

[0008] The delayed setting packer includes a center pipe. An outer center pipe is provided outside the center pipe, and an annular cavity is provided between the center pipe and the outer center pipe. A cylinder body is provided outside the outer center pipe. A piston is provided in the upper part of the annulus between the outer center pipe and the cylinder body, a sealing plug is provided in the middle part of the annulus, and a sealing cap is provided at the bottom of the annulus. A first damping oil sealing cavity is formed between the piston and the sealing plug, a second damping oil sealing cavity is formed between the sealing plug and the sealing cap, and the first damping oil sealing cavity and the second damping oil sealing cavity are communicated through a damping pipe. The lower end of the cylinder body is connected to the main body, and the injection water nozzle is located in the main body.

[0009] The first damping oil sealing cavity and the second damping oil sealing cavity are provided with damping oil, and the damping pipe is a capillary tube wound outside the outer center pipe.

[0010] An axial eccentric channel is provided on the side wall of the main body. A spring is arranged in the eccentric channel. A water distribution plug, an injection water nozzle and a temporary plug soluble body are successively arranged at the lower end of the spring. A plug is arranged at the lower end of the temporary plug soluble body. The inner wall of the eccentric channel communicates with the injection liquid channel in the main body interior and the inner tube center through an injection liquid outlet hole.

[0011] The piston and the cylinder body are connected by a shear pin. A through hole is opened on the side wall of the cylinder body corresponding to the sealing cap, and a sealing glue nail is arranged in the through hole.

[0012] The bottom of the inner central tube and the main body are connected by a flow-through connecting sleeve. An annular cavity is arranged between the flow-through connecting sleeve and the cylinder body. The lower end of the main body is connected to a lower joint. An axial through hole is opened on the lower joint, and the through hole communicates with the produced liquid channel.

[0013] The flow-through channel on the lower joint, the flow-through channel on the main body, the annulus between the flow-through connecting sleeve and the cylinder body, and the annulus between the inner central tube and the outer central tube together form the produced liquid channel.

[0014] The delayed setting packer includes delayed setting packer A, delayed setting packer B, and delayed setting packer C. The delayed setting times of the three delayed setting packers are t1, t2, and t3 respectively, and t1 < t2 < t3.

[0015] The present invention has the following beneficial effects: Due to the adoption of the above solution, the present invention can realize multi-stage stratified injection and production of the downhole oil-water separation injection and production process, and realize the effective setting of multiple packers under the setting load condition of a single-stage packer, thereby avoiding continuously increasing the setting load of the pipe string due to the increase in the number of packers, avoiding the unreliable setting of the packer, improving the stress state of the pipe string, reducing or avoiding the bending of the pipe string under large loads, reducing the fatigue damage of the pipe string, preventing the eccentric wear between the sucker rod and the tubing, and prolonging the service life of the pipe string and the rod string; it can realize the setting and verification of multiple packers in the downhole oil-water separation injection and production pipe string, and improve the reliability and service life of the process. Description of the Drawings

[0016] Figure 1 is the structural schematic diagram of the present invention; Figure 2 is the structural schematic diagram of the tubing hanger and the wellhead tubing loading device; Figure 3 is the structural schematic diagram of the delayed setting packer; Figure 4 is the schematic diagram of the cross-sectional bridge channel of the delayed setting packer.

[0017] In the figure, 1 - plug, 2 - oil - water separator, 3 - tail pipe, 4 - injection pump, 5 - disconnecter, 6 - anchor packer, 8 - inner pipe, 9 - outer pipe, 10 - 1 - delayed setting packer A, 10 - 2 - delayed setting packer B, 10 - 3 - delayed setting packer C, 11 - sealing plunger, 12 - production pump, 13 - special tubing hanger, 13 - 1 - bearing seat, 13 - 2 - tubing hanger, 13 - 3 - central pipe, 13 - 4 - telescopic pipe, 13 - 5 - sealing sleeve, 14 - tubing, 15 - sucker rod, 16 - 1 - first injection layer, 16 - 2 - second injection layer, 16 - 3 - third injection layer, 17 - production layer, 18 - wellhead tubing loading device, 19 - loading crossbeam assembly, 20 - compression nut, 21 - bearing nipple, 22 - special packing box, 23 - polished rod, 24 - production fluid channel, 25 - injection fluid channel, 101 - inner joint, 102 - central pipe, 103 - outer joint, 104 - upper spacer ring, 105 - outer central pipe, 106 - rubber cylinder, 107 - spacer ring, 108 - lower spacer ring, 109 - pin, 110 - setting pin, 111 - piston, 112 - cylinder block, 113 - first damping oil seal cavity, 114 - sealing plug, 115 - damping pipe, 116 - second damping oil seal cavity, 117 - sealing rubber nail, 118 - sealing cap, 119 - flow - through connecting sleeve, 120 - main body, 121 - spring, 122 - water - distribution plug, 123 - injection water nozzle, 124 - temporary plugging soluble body, 125 - plug, 126 - lower joint, 127 - flow - through channel, 128 - injection fluid outlet hole. Embodiment

[0018] The present invention will be further described below with reference to the accompanying drawings: As Figures 1 to 4 shown, a downhole oil - water separation multi - layer injection - production process string for step - by - step setting and seal checking includes a sucker rod 15 and a tubing 14. The tubing 14 is connected to a tubing hanger 13, and the lower end of the sucker rod 15 is connected to a production pump 12. The lower end of the production pump 12 is connected to a string. Inside the upper end of the string, there is a sealing plunger 11. A number of delayed setting packers are connected to the string. The number of delayed setting packers is the same as the number of injection layers, and each delayed setting packer is respectively located on the corresponding injection layer. The lower end of the string is connected to an anchor packer 6. The plunger of the production pump 12 is connected to the plunger of an injection pump 4 through a sucker rod. The injection pump 4 is located below the anchor packer 6. An oil - water separator 2 is provided below the injection pump 4. The oil - water separator 2 corresponds to the production layer 17. A tail pipe 3 is provided below the oil - water separator 2, and the lower end of the tail pipe 3 is connected to a plug 1. The string includes an inner pipe 8 and an outer pipe 9. There is an annular cavity between the inner pipe 8 and the outer pipe 9. The inside of the inner pipe 8 is an injection fluid channel 25, and the annulus between the inner and outer pipes is a production fluid channel 24.

[0019] The delayed setting packer includes an inner joint 101, the upper end of the inner joint 101 is connected to the inner pipe 8. The lower end of the inner joint 101 is connected to a central pipe 102, an outer central pipe 105 is arranged outside the central pipe 102, and an annulus is provided between the two. The upper end of the outer central pipe 105 is connected to an outer joint 103, the upper end of the outer joint 103 is connected to the outer pipe 9, and an axial through hole is opened on the outer joint 103, so that the annulus between the central pipe 102 and the outer central pipe 105 communicates with the produced fluid channel 25. An outer rubber cylinder 106 is arranged outside the outer central pipe 105, an upper spacer ring 104 is arranged at the upper end of the rubber cylinder 106, a lower spacer ring 108 is arranged at the lower end, the rubber cylinder 106 is composed of a plurality of rubber cylinder monomers, and a middle spacer ring 107 is arranged between the rubber cylinder monomers.

[0020] The lower end of the lower spacer ring 108 is connected to a cylinder body 112 through a pin 109. A piston 111 is arranged in the annulus formed between the cylinder body 112 and the outer central pipe 105, and the piston 111 is connected to the cylinder body 112 through a shear pin 110. A sealing plug 114 is further arranged in the middle of the annulus formed between the cylinder body 112 and the outer central pipe 105. A sealing cap 118 is arranged below the sealing plug 114. A first damping oil sealing cavity 113 is formed between the piston 111 and the sealing plug 114, a second damping oil sealing cavity 116 is formed between the sealing plug 114 and the sealing cap 118, and the first damping oil sealing cavity 113 and the second damping oil sealing cavity 116 are communicated through a damping pipe 115; a through hole is opened on the side wall of the cylinder body 112 corresponding to the sealing cap 118, and a sealing rubber nail 117 is arranged in the through hole. The first damping oil sealing cavity 113 and the second damping oil sealing cavity 116 are filled with damping oil. The damping pipe 115 is a long capillary tube that can withstand a high pressure of 35 MPa, and the damping pipe can be wound around the outer central pipe.

[0021] The lower end of the outer central pipe 105 is connected to a flow-through connecting sleeve 19. An annulus is also provided between the flow-through connecting sleeve 19 and the external cylinder body 112. The flow-through connecting sleeve 19 and the lower end of the cylinder body 112 are connected to a main body 120. An axial eccentric channel is arranged on the side wall of the main body 120. A spring 121 is arranged at the top inside the eccentric channel. A water distribution plug 122, an injection water nozzle 123 and a temporary plug soluble body 124 are sequentially arranged below the spring 121. A plug 125 is arranged below the temporary plug soluble body 124. Injection liquid outlet holes 128 are arranged on the inner wall of the eccentric channel, and the injection liquid outlet holes 128 communicate with the inside of the main body 120, and thus communicate with the injection liquid channel 25 inside the inner pipe 8. The outside of the injection water nozzle 123 communicates with the injection layer 16, and liquid can be injected into the injection layer 16. A flow-through channel 127 is arranged on the main body 120. The lower end of the main body 120 is connected to a lower joint 126. An axial through hole is opened on the lower joint 126. The through hole on the lower joint 126, the flow-through channel 127 communicate with the produced fluid channel 24 between the oil-water separator 2, the inner pipe 8 and the outer pipe 9.

[0022] The temporary plugging soluble body 124 is made of soluble material, which can slowly dissolve under well fluid conditions. The undissolved body has a certain mechanical strength, and the time for it to completely dissolve and lose the temporary plugging ability can be set by selecting materials and sizes, and can be controlled within several hours to several days according to needs. Each delayed setting packer controls the opening time of the injection channel by setting different temporary plugging soluble bodies. The temporary plugging soluble body 124 is located between the water distribution plug 122 and the plug 125, plugs at the liquid outlet hole 128 of the injection fluid, and temporarily closes the injection channel when going down the well; after the temporary plugging soluble body 124 dissolves underground for a period of time, it will yield the injection channel, and the water distribution plug 122 will be located at the liquid outlet hole 128 of the injection fluid under the action of the spring 121 and the injection pressure, connecting the injection channel.

[0023] The special tubing hanger 13 is composed of a carrier seat 13-1, a tubing hanger 13-2, a central tube 13-3, a telescopic tube 13-4, and a sealing sleeve 13-5. A carrier nipple 21 passes through the inside of the carrier seat 13-1, and the carrier seat 13-1 is connected to the tubing hanger 13-2 by bolts. The top of the tubing hanger 13-2 is a turnip head structure suspended at the wellhead, and the lower inner cavity is threadedly connected to the central tube 13-3. The lower end of the central tube 13-3 is internally threadedly connected to the telescopic tube 13-14, and the two are limited by steps. The lower end of the telescopic tube 13-14 is connected to the tubing 14. A large pitch thread is provided between the central tube 13-3 and the telescopic tube 13-4. Rotating the carrier seat 13-1 can adjust the up and down position of the tubing hanger 13-2 on the pipe string. The sealing sleeve 13-5 is threadedly connected to the outside of the central tube 13-3 and can freely move up and down along the telescopic tube 13-4 with the central tube 13-3. With the carrier nipple 21 and the tubing 14 fixed, the special tubing hanger 13 is screwed back to the wellhead four-way suspension to complete the wellhead suspension of the pipe string.

[0024] The load-bearing jumper 21 is a hollow circular tube structure. The polished rod 23 and the sucker rod 15 can pass through its interior. Its upper part is connected to the special stuffing box 22, the middle part is connected to the loading crossbeam assembly 19 and the compression cap 20, and the lower part is threadedly connected to the telescopic pipe 13-4. The load-bearing jumper 21 is externally provided with a loading crossbeam assembly 19, and the two are connected by threading or slip locking. There is a bearing inside the loading crossbeam assembly 19, which enables it to rotate horizontally around the load-bearing jumper 21. The loading crossbeam assembly 19 is threadedly connected to the loading arm of the wellhead tubing loading device 18. The loading crossbeam assembly 19 is externally connected to the wellhead tubing loading device 18. The wellhead tubing loading device 18 is an auxiliary process device supporting the multi-stage delayed setting and sealing verification processes of the packer. It is installed on the casing cross joint of the oil well wellhead. The lifting and lowering actions of the downhole tubing string are realized through the loading crossbeam assembly 19, and it can move up and down within the stroke range under the condition of constant loading. The position is locked by the safety lock mechanism and a constant load is applied; the supporting visual mechanical scale can record the displacement of the tubing 15 moving up and down and the locking position. The pressurizing load of the wellhead string can be adjusted and set. The special stuffing box 22 is threadedly connected to the load-bearing jumper 21. There is a sealing packing inside to seal with the polished rod 23, and there is an oil outlet on the side that can be connected to the ground production pipeline.

[0025] The following takes the scheme of injecting into the upper layer while producing from the lower layer as an example to describe the setting and sealing verification processes. The packer setting and sealing verification processes corresponding to different relative positions of other injection layers and production layers are similar to this.

[0026] Assume the injection and production layer conditions of the oil well are as Figure 1 shown. There are a total of 4 layers. Among them, the upper three layers are injection layers, namely the first injection layer 16-1, the second injection layer 16-2, and the third injection layer 16-3. The lowermost layer is the production layer 17. The water absorption indices of the three injection layers have been measured through the pre-injection process. The injection layers and the production layer 17 are separated by three delayed setting packers and the lower anchoring packer 6. The delayed setting packers include the delayed setting packer A 10-1, the delayed setting packer B 10-2, and the delayed setting packer C 10-3. According to the different lengths of the damping tubes 115 inside and / or the different damping oils, the delayed setting times of the three delayed setting packers are t1, t2, and t3 respectively, where t1 < t2 < t3.

[0027] According to the different positions of the reinjection enhanced injection layer, the combination method of the delayed setting packer and the pre-arranged temporary plugging soluble material at the water injection port end, the tubing string scheme is divided into the following three cases: The first type: when the reinjection reinforcement layer is the uppermost first water injection layer 16-1, the packer string is in the order of delayed setting packer A10-1, delayed setting packer C10-3, delayed setting packer B10-2 and anchor packer 6 from top to bottom, among which the bridge-type water injection ports of delayed setting packer B10-2 and delayed setting packer C10-3 need to be pre-filled with temporary plugging soluble materials, such as Figure 1 shown.

[0028] The second type: When the reinjection reinforcement layer is the second water injection layer 16-2, the order of lowering the isolation string is the same as that in case 1, but the bridge-type water injection port ends of the delayed setting packer A10-1 and the delayed setting packer C10-2 need to be pre-placed with temporary plugging soluble materials.

[0029] The third type: When the reinjection reinforcement layer is the third water injection layer 16-3, the isolation string is in the order of delayed setting packer A10-1, delayed setting packer B10-2, delayed setting packer C10-3 and anchor packer 6 from top to bottom. The bridge-type water injection port ends of the delayed setting packer A10-1 and the delayed setting packer B10-2 need to be pre-installed with temporary plugging soluble materials.

[0030] Let's take the first case as an example (such as Figure 1 ), the setting and verification process of the delayed setting isolation column is as follows: 1. Preliminary preparation The downhole oil-water separation injection and production multi-layer isolation process pipe string connecting the special oil pipe hanger 13 and the load-bearing short-circuit 21 is lowered to the designed position, and the upper end of the load-bearing short-circuit 21 is connected to the lifting short-circuit.

[0031] Lower the polished rod 23, sucker rod 15, and disconnector 5 to the designed depth, and complete the connection with the production pump 11 and injection pump 4. Adjust the sucker rod string according to the design requirements of the anti-shock distance, lower the rod string to the predetermined position at the wellhead, and remove the sucker rod elevator.

[0032] 2. Install the wellhead tubing loading device 18 and the loading beam assembly 19 Install the wellhead tubing loading device 18 to the wellhead, install the loading beam assembly 19 on the load-bearing short-circuit 21, put on the locking cap 20, and install the special packing box 22. At this time, the wellhead tubing loading device 18 and the loading beam assembly 19 are in a separated state, and the loading beam assembly 19 is in the middle position of the loading arms on both sides of the wellhead tubing loading device 18, and its lifting and lowering will not interfere with the wellhead tubing loading device 18.

[0033] 3. Setting anchor packer 6 Install the tubing elevator on the lower part of the lifting nipple. Use the draw works hook and the tubing elevator to lift and lower the tubing string, and complete the anchoring and setting of the bottom - anchored packer 6 in cooperation with the rotation of the tubing string. Synchronously record the change in the hook load of the tubing string. After setting, the upper end face of the special tubing hanger 13 is within the range of the designed dimension from the upper end face of the wellhead cross flange, and synchronously record the scale position of the wellhead tubing loading device 18.

[0034] 4. Connect the wellhead tubing loading device 18 and the loading beam assembly 19 into one body Use the draw works hook and the tubing elevator to slowly lift the tubing string and record the hook load of the tubing string. When the hook load reaches the designed weight, stop lifting. Rotate the loading beam assembly 19 installed on the tubing string by 90 degrees, and use the loading mechanism on the wellhead tubing loading device 18 to complete the connection and upward load - bearing of the wellhead tubing loading device 18 and the loading beam assembly 19, transfer the tubing string load acting on the draw works hook to the wellhead tubing loading device 18. Synchronously observe the hook load until it drops to 0t, then stop the upward movement of the wellhead tubing loading device 18 and maintain the loading state, and remove the tubing elevator.

[0035] 5. Install the pumping unit walking beam and related testing instruments Use the draw works hook and the sucker rod elevator to lift the polished rod 23 to the designed height, lock the lock nut of the special stuffing box 22, and install the pumping unit walking beam and the suspension rope device. Connect the production channel of the special stuffing box 22 to the production pipeline, and install the dynamometer testing instrument, pressure gauge, etc., and make preparations before trial pumping.

[0036] 6. Trial production Start the pumping unit for trial production. Start pumping with appropriate stroke and stroke frequency parameters, synchronously test the polished rod load, and observe the measured liquid production volume and the overflow volume at the oil - casing annulus outlet.

[0037] 7. Setting and sealing verification of the delayed - setting packer A10 - 1 Keep the pumping unit in the pumping state, and the wellhead tubing loading device 18 continuously applies a constant setting load to the tubing string. Synchronously record the downward displacement, polished rod load, liquid production volume, and overflow volume at the oil - casing annulus outlet. When the loading time is t1 and the downward displacement is about x1, at this time the delayed - setting packer A10 - 1 is completely set. At this time, all injection layers and production layer 17 will be separated, and the oil - casing annulus is separately connected to the production layer 17. By comparing and observing the overflow volume at the oil - casing annulus outlet, the change in the polished rod load, and the water absorption index of the three injection layers, it can be judged whether the bottom - anchored packer 6 and the delayed - setting packer A10 - 1 are reliably sealed.

[0038] 8. Setting and sealing verification of the delayed - setting packer B10 - 2 The wellhead tubing loading device 18 continuously applies a constant setting load to the tubing string, and simultaneously records the downward displacement, hook load, liquid production volume, and overflow volume at the annulus outlet of the tubing and casing. When the loading time is t2 and the downward displacement is approximately x2, the delayed setting packer B10-2 is fully set at this time, and the second injection layer 16-2 and the third injection layer 16-3 will be blocked. By testing and comparing the change in the hook load and the water absorption index of the second injection layer 16-2 and the third injection layer 16-3, it can be determined whether the delayed setting packer B10-2 provides reliable sealing.

[0039] 9. Setting and sealing verification of the delayed setting packer C10-3 The wellhead tubing loading device 18 continuously applies a constant setting load to the tubing string, and simultaneously records the downward displacement, hook load, liquid production volume, and overflow volume at the annulus outlet of the tubing and casing. When the loading time is t3 and the downward displacement is approximately x3, the delayed setting packer C10-3 is set at this time, and the first injection layer 16-1 and the second injection layer 16-2 will be blocked. By testing and comparing the change in the hook load and the water absorption index of the overall injection layer, it can be determined whether the delayed setting packer C10-3 provides reliable sealing.

[0040] 10. Install the special tubing hanger 13 in place at the predetermined wellhead position After all the packers are set and the sealing verification is qualified, the pumping unit is shut down. Control the wellhead tubing loading device 18 to lock the loading position. Under the condition that the loading force continues to remain constant, drive the tubing hanger 13-2 and the sealing sleeve 13-4 to rotate and lift around the central pipe 13-3 by rotating the bearing seat 13-1, and install the special tubing hanger in place at the predetermined wellhead position and fasten it.

[0041] 11. Unload the tubing loading device 18 and remove the wellhead tubing loading device 18, the loading beam assembly 19, the load-bearing nipple 21, and the bearing seat 13-1 Remove the loading load of the wellhead tubing loading device 18, and remove the wellhead connection pipelines and supporting testing instruments; disconnect the polished rod 23 from the horsehead and remove the donkey head. Loosen the lock nut of the special stuffing box 22, lower the polished rod 23 and the sucker rod 15, and remove the wellhead tubing loading device 18, the loading beam assembly 19, the load-bearing nipple 21, and the bearing seat 13-1.

[0042] 12. Connect the surface flow pipelines and start production Pay attention to the stroke adjustment distance, make a good square clamp, install the donkey head, connect the surface flow pipelines, and start production.

[0043] After the production well is put into production, the oil-water mixture in the production layer 17 is separated by the oil-water separator 2. The produced liquid with low water cut enters the inlet of the production pump 12 through the production liquid channel 24 between the bottom anchored packer 6, the delayed setting packer, the inner pipe 8 and the outer pipe 9 through the oil-casing annulus at the upper part of the oil-water separator 2, and then is lifted to the ground by the production pump 12. The separated water enters the injection pump 4 through the central pipe and the tail pipe 3 of the oil-water separator 2 for pressurization, and then is injected into the corresponding injection layer through the injection liquid channel 25 between the inner pipe 8 and the sucker rod 14 and the injection water nozzle 123 of the delayed setting packer. The injection liquid volume of each injection layer is achieved by installing injection water nozzles 123 with different diameters and adjusting the displacement of the injection pump 4.

Claims

1. A downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal verification, comprising a production pump (12) and an injection pump (4), characterized in that: The lower end of the production pump (12) is connected to a pipe string, and several delayed setting packers are connected to the pipe string. The number of delayed setting packers is the same as the number of injection layers. The lower end of the pipe string is connected to an anchoring packer (6). The several delayed setting packers and the anchoring packer (6) separate the water injection layer and the production layer; The injection pump (4) is located below the anchoring packer (6), and an oil-water separator (2) is provided below the injection pump (4); The pipe string includes an inner pipe (8) and an outer pipe (9), and an annular cavity is provided between the inner pipe (8) and the outer pipe (9); The delayed setting packer includes an injection water nozzle (123). The inside of the injection water nozzle (123) communicates with the center of the inner pipe (8) through a water distribution plug (122), and the outside of the injection water nozzle (123) communicates with the injection layer (16); A flow-through channel (127) is also provided on the delayed setting packer (10). The flow-through channel (127) communicates with the oil-water separator (2) and the annular cavity between the inner pipe (8) and the outer pipe (9) to form a produced fluid channel (24).

2. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal checking according to claim 1, wherein: It also includes a special tubing hanger (13). The special tubing hanger (13) includes a bearing seat (13-1). The lower part of the bearing seat (13-1) is connected to the tubing hanger (13-2) by bolts. The lower end of the tubing hanger (13-2) is internally threaded to connect a central pipe (13-3). The lower end of the central pipe (13-3) is internally connected to a telescopic pipe (13-4). The outside of the lower end of the central pipe (13-3) is connected to a sealing sleeve (13-5); The lower end of the telescopic pipe (13-4) is connected to the tubing (14). By rotating the bearing seat (13-1), the up and down position of the tubing hanger (13-2) on the pipe string can be adjusted.

3. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal checking according to claim 2, characterized in that: A bearing nipple (21) passes through the inside of the bearing seat (13-1). An upper loading beam assembly (19) is fixed outside the bearing nipple (21). The bottom of the bearing nipple (21) is threaded to connect the telescopic pipe (13-4).

4. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal checking according to claim 1, characterized in that: The delayed setting packer (10) includes a central pipe (102). An outer central pipe (105) is provided outside the central pipe (102), and an annular cavity is provided between the central pipe (102) and the outer central pipe (105); A cylinder body (112) is provided outside the outer central pipe (105). A piston (111) is provided in the upper part of the annulus between the outer central pipe (105) and the cylinder body (112). A sealing plug (114) is provided in the middle of the annulus, and a sealing cap (118) is provided at the bottom of the annulus. A first damping oil sealing cavity (113) is formed between the piston (111) and the sealing plug (114), and a second damping oil sealing cavity (116) is formed between the sealing plug (114) and the sealing cap (118). The first damping oil sealing cavity (113) and the second damping oil sealing cavity (116) are connected through a damping pipe (115); The lower end of the cylinder body (112) is connected to the main body (120), and the injection water nozzle (123) is located in the main body (120).

5. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and sealing as claimed in claim 4, characterized in that: Damping oil is provided in the first damping oil sealing cavity (113) and the second damping oil sealing cavity (116), and the damping pipe (115) is a capillary tube wound outside the outer central pipe (105).

6. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal verification according to claim 5, characterized in that: An axial eccentric channel is provided on the side wall of the main body (120). A spring (121) is arranged in the eccentric channel. A water distribution plug (122), an injection nozzle (123) and a temporary plugging soluble body (124) are successively arranged at the lower end of the spring (121). A plug (125) is arranged at the lower end of the temporary plugging soluble body (124); and the inner wall of the eccentric channel communicates with the injection liquid channel (25) at the center of the interior of the main body and the inner pipe (8) through an injection liquid outlet hole (128).

7. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and sealing according to claim 6, characterized in that: The piston (111) is connected to the cylinder block (112) through a shear pin (110). A through hole is opened on the side wall of the cylinder block (112) corresponding to the sealing cap (118), and a sealing glue nail (117) is arranged in the through hole.

8. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal checking according to claim 7, characterized in that: The bottom of the inner central pipe (102) is connected to the main body (120) through a flow-through connecting sleeve (119). An annular cavity is arranged between the flow-through connecting sleeve (119) and the cylinder block (112); the lower end of the main body (120) is connected to a lower joint (126), and an axial through hole is opened on the lower joint (126), and the through hole communicates with the produced liquid channel (24).

9. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal verification according to claim 8, characterized in that: The flow-through channel on the lower joint (126), the flow-through channel (127) on the main body (120), the annulus between the flow-through connecting sleeve (119) and the cylinder block (120), and the annulus between the inner central pipe (102) and the outer central pipe (105) together form the produced liquid channel (24).

10. The downhole oil-water separation multi-layer injection-production process string for step-by-step setting and seal verification according to claim 9, characterized in that: The delayed setting packer includes a delayed setting packer A (10-1), a delayed setting packer B (10-2), and a delayed setting packer C (10-3). The delayed setting times of the three delayed setting packers are t1, t2, and t3 respectively, and t1 < t2 < t3.

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