A differential pressure self-balanced continuous injection-production well completion structure and implementation method

Abstract

The application discloses a differential pressure self-balancing continuous injection-production well completion structure and an implementation method thereof. The well completion structure comprises a well shaft, a pipe string arranged in the well shaft, and a differential pressure self-balancing assembly arranged on the pipe string. The differential pressure self-balancing assembly comprises a central pipe, a flow hole arranged on the central pipe, an outer shield arranged outside the central pipe, a movable sliding sleeve arranged in a cavity between the central pipe and the outer shield and used for opening or closing the flow hole, and a limiting device arranged on one side of the movable sliding sleeve and an elastic element arranged on the other side of the movable sliding sleeve. The movable sliding sleeve is in sliding connection with the central pipe. The differential pressure self-balancing continuous injection-production well completion structure can repeatedly open and close the flow channel through the differential pressure of the outer part and the inner part of the pipe string, balance control of the production differential pressure and the liquid production volume is realized, the low differential pressure stable oil production in the early production stage and the large liquid production by releasing the differential pressure in the later production stage are realized, stable oil production and the production effect of taking water to carry oil are realized, and the operation purpose of oil well injection conversion can also be realized through the mode of the immovable pipe string.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas field development, in particular to a pressure differential self-balancing continuous injection-production well completion structure and implementation method. BACKGROUND

[0002] In the water drive type reservoir and water injection development mode, most of the oil wells have low water content in the early production stage, and with the increase of production time, the water phase continuously breaks through, causing the water content of the oil well to continuously increase, and the production discharge needs to be increased to ensure the daily output of crude oil, that is, the so-called water-oil process. However, in the long-term production process, the flow pore of the downhole sand control screen pipe or perforated pipe and other well completion equipment is blocked by fine powder particles, mud, heavy oil colloid and asphaltene, the overall permeability decreases in a "landslide" manner, resulting in reduced flow performance of the well completion pipe string, increased production pressure, and certain production pressure on the submersible electric pump and other lifting equipment, which affects the large-discharge liquid production of the oil well.

[0003] The current conventional treatment method is to use acidizing and other measures to remove the blockage. However, the implementation process needs to stop the pump and shut down the well, and the implementation effect is difficult to predict. In the late production stage of the oil well, according to the injection-production demand of the oilfield, if the oil production well needs to be converted into a water injection well, the pump needs to be stopped and the well needs to be shut down, and the original oil production string needs to be pulled out and replaced with a water injection string. The pipe string operation not only affects the production, but also causes a large construction cost. SUMMARY

[0004] In order to solve the limitations and influences of the existing injection-production well on oil production and oil well conversion construction, the present application provides a pressure differential self-balancing continuous injection-production well completion structure and implementation method which can realize large-liquid production without shutting down the well and stopping production and direct oil well to water well conversion without moving the pipe string.

[0005] In the first aspect, the present application provides a pressure differential self-balancing continuous injection-production well completion structure, which is realized by adopting the following technical scheme.

[0006] A pressure differential self-balancing continuous injection-production well completion structure, comprising a wellbore, a pipe string arranged in the wellbore, a sand control pipe arranged on the pipe string, and a pressure differential self-balancing assembly arranged on the pipe string; the pressure differential self-balancing assembly comprises a central pipe, and a plurality of flow holes are arranged on the central pipe; an outer shield is arranged outside the central pipe, and a movable sliding sleeve for opening or closing the flow holes is arranged in the cavity between the central pipe and the outer shield, and the movable sliding sleeve is in sliding connection with the central pipe; an elastic member is arranged on one side of the movable sliding sleeve, and a limiting device is arranged on the other side of the movable sliding sleeve; and the pressure differential self-balancing assembly further comprises a sand control filtering mechanism.

[0007] Further, the limiting device is fixed on the central pipe, and the limiting device comprises an annular body, a locking groove is formed in the middle of the outer wall of the body in the circumferential direction, and a lead-in chamfer is formed in the edge of the body in the circumferential direction.

[0008] Further, the mobile sliding sleeve comprises an annular base body, and a locking mechanism is arranged on the circumferential surface of one end of the base body at intervals; two sliding sealing rings are arranged on the inner wall of the base body.

[0009] Further, the locking mechanism is a hook claw with elasticity.

[0010] Further, a base is arranged on the outer wall of the central pipe, and the elastic member is arranged on the base.

[0011] Further, a shearing groove is formed at one end of the base, and a shearing ring is arranged in the shearing groove of the base.

[0012] Further, the sliding sealing ring on the side of the mobile sliding sleeve away from the locking mechanism is located between the shearing ring and the elastic member; and the sliding sealing ring on the side close to the locking mechanism is located on the central pipe in front of the base.

[0013] Further, an end ring and a flow-through end ring are further arranged outside the central pipe, the flow-through end ring is located between the end ring and the outer shield, and a through hole is formed between the flow-through end ring and the central pipe.

[0014] Further, the sand prevention and filtration mechanism is arranged between the end ring and the flow-through end ring.

[0015] By adopting the above technical scheme, when the pressure difference between the external pressure and the internal pressure of the well completion string is less than the opening pressure of the differential pressure self-balancing assembly, the mobile sliding sleeve of the differential pressure self-balancing assembly is in the initial position, and the flow-through channel is in the closed state; when the pressure difference between the external pressure and the internal pressure of the well completion string is greater than the opening pressure of the differential pressure self-balancing assembly, the mobile sliding sleeve of the differential pressure self-balancing assembly moves to the right and compresses the elastic member, and the flow-through channel is in the open state; when the pressure difference between the external pressure and the internal pressure of the well completion string decreases, the mobile sliding sleeve can be self-reset under the action of the elastic member, so as to realize the differential pressure self-balancing opening and closing; when the internal pressure of the well completion string is greater than the external pressure and the pressure difference reaches a certain value, the mobile sliding sleeve can push the shearing ring to be sheared, the mobile sliding sleeve moves to the limiting device, the locking mechanism is locked with the locking groove, and the flow-through channel is completely opened.

[0016] In the second aspect, the application provides an implementation method of the differential pressure self-balancing continuous injection and production, which is realized by adopting the following technical scheme.

[0017] The implementation method of the differential pressure self-balancing continuous injection and production adopts the well completion structure of the differential pressure self-balancing continuous injection and production, and any one of the following is included in the implementation method.

[0018] a. During normal production, under the lifting action of the electric submersible pump, the flow-through channel of the differential pressure self-balancing assembly is in the closed state, and the fluid enters the inside of the well completion string from the screen pipe or the perforated pipe of the well completion string.

[0019] b. When the oil well liquid production does not reach the allocation index or needs to increase liquid production, the production pressure difference is increased by controlling the submersible electric pump, the flow passage of the differential pressure self-balancing assembly is automatically opened, the flow area from the production layer to the inside of the pipe string is increased, and the purpose of large liquid production is realized;

[0020] c. When it is needed to reduce liquid production or temporarily shut down the well, the production pressure difference is reduced by controlling the submersible electric pump, the flow passage of the differential pressure self-balancing assembly is automatically closed, the purpose of low liquid production or well shut down to reduce leakage is realized;

[0021] d. When the oil well needs to be converted into a water injection well, the wellhead is pressed or a special pipe string is lowered to press inside the differential pressure self-balancing assembly, the flow passage is opened to the normally open position, and the purpose of water injection operation is realized.

[0022] The present application has the following beneficial effects.

[0023] The present application realizes the repeated self-balancing opening and closing of the flow passage through the differential pressure outside and inside the pipe string, realizes the balanced control of the production pressure difference and the liquid production, plays the role of low pressure difference stable oil production in the early production stage and large liquid production by releasing the pressure difference in the later production stage, and thus realizes the stable oil production and the production effect of taking oil with water. The present application can also realize the operation purpose of oil well conversion by opening the flow passage to the normally open position without moving the pipe string. The present application improves the oil production effect and the convenience of oil well conversion operation, avoids the influence of pump shutdown and well shut down for workover operation or pipe string operation on the electric pump unit, avoids the damage of workover to the reservoir, and also saves the construction cost. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a well completion structure schematic diagram of the present application;

[0025] Figure 2 is a structure schematic diagram of the differential pressure self-balancing production tool of the present application;

[0026] Figure 3 is a schematic diagram of the installation position of the shear ring aiming to embody the present application;

[0027] Figure 4 is Figure 3 is an enlarged view of A part in figure 6;

[0028] Figure 5 is a structure schematic diagram of the limiting device of the present application;

[0029] Figure 6 is a structure schematic diagram of the locking mechanism of the present application;

[0030] Figure 7 is a schematic diagram of the initial closed state of the flow passage of the well completion structure of the present application;

[0031] Figure 8 is a schematic diagram of the open state of the flow passage of the completion structure of the application;

[0032] Figure 9 is a schematic diagram of the pressurized opening of the flow passage in the completion structure of the application;

[0033] Figure 10 is a schematic diagram of the conversion of the completion structure to the injection state.

[0034] wherein 1. central pipe; 2. sand prevention and filtration mechanism; 3. limiting device; 31. locking groove; 32. lead-in chamfer; 33. body; 4. movable sliding sleeve; 41. locking mechanism; 42. sliding sealing ring; 43. base; 5. flow hole; 6. shear ring; 61. outer shear fragment; 62. inner shear fragment; 7. base; 8. elastic member; 9. outer shroud; 10. wellbore; 11. pipe string; 12. hanging packer; 13. sand prevention pipe; 14. differential pressure self-balancing assembly; 15. blind plug; 16. end ring; 17. flow end ring. DETAILED DESCRIPTION

[0035] The application will be further described below in conjunction with the drawings and examples.

[0036] As shown in the drawings, Figures 1-10 a differential pressure self-balancing continuous injection and production completion structure, comprising a wellbore 10, a pipe string 11, a hanging packer 12, a sand prevention pipe 13, a differential pressure self-balancing assembly 14, and a blind plug 15. The wellbore 10 is provided with the pipe string 11, and the wellbore 10 and the pipe string 11 at the wellhead are sealed by the hanging packer 12. The pipe string 11 is provided with a plurality of sand prevention pipes 13, which can be screen pipes, perforated pipes, or other sand prevention and filtration tools. The pipe string 11 is also provided with the differential pressure self-balancing assembly 14, and the end of the pipe string 11 is plugged by the blind plug 15.

[0037] The differential pressure self-balancing assembly 14 of the application comprises a central pipe 1, a sand prevention and filtration mechanism 2, a limiting device 3, a movable sliding sleeve 4, a flow hole 5, a shear ring 6, a base 7, an elastic member 8, and an outer shroud 9.

[0038] The central pipe 1 is circumferentially and radially provided with a plurality of flow holes 5, which are hard alloy tubular members fastened to the side wall of the central pipe 1 by threads to form a flow passage.

[0039] The base 7 is provided on one side of the central pipe 1 in the flow passage, is sleeved on the central pipe 1 and fastened thereto, the elastic member 8 (preferably a spring) is sleeved on the base 7 and is in a pre-compressed state in the initial state. One end of the base 7 is provided with a shear groove, and the shear ring 6 is sleeved on the shear groove of the base 7. The shear ring 6 is made of a metal member with a certain shear strength and can be sheared and broken under a certain force.

[0040] The limiting device 3 is arranged on the center pipe 1 on the other side of the flow channel, is sleeved on the center pipe 1, and comprises an annular body 33, a locking groove 31 is formed in the middle of the outer wall of the body 33 in the circumferential direction, and an introduction chamfer 32 is formed on the edge of the body 33 in the circumferential direction, which can guide the locking mechanism 41 to enter the locking groove 31.

[0041] The movable sliding sleeve 4 is sleeved on the center pipe 1 between the base 7 and the limiting device 3 and can slide along the center pipe 1. The movable sliding sleeve 4 comprises an annular base body 43, and a locking mechanism 41 is arranged on the circumferential surface of one end of the base body 43 at a distance, and the locking mechanism 41 can be a hook claw with elasticity. Two sliding sealing rings 42 are arranged on the inner wall of the base body 43. Specifically, the sliding sealing ring 42 on the side, away from the locking mechanism 41, of the movable sliding sleeve 4 is located between the shear ring 6 and the elastic member 8; and the sliding sealing ring 42 on the side, close to the locking mechanism 41, of the movable sliding sleeve 4 is located on the center pipe 1 before the base 7, and in the initial state, the two sealing rings are located on the two sides of the flow hole 5, respectively.

[0042] The limiting device 3, the movable sliding sleeve 4 and the elastic member 8 are externally provided with an outer protective cover 9 for protecting the above structure. The center pipe 1 is further provided with an end ring 16 and a flow end ring 17, and the flow end ring 17 is located between the end ring 16 and the outer protective cover 9. One end of the outer protective cover 9 is tightly connected and sealed with the center pipe 1, and the other end of the outer protective cover 9 is overlapped on the flow end ring 17; a through hole for fluid flow is formed between the flow end ring 17 and the center pipe 1. The sand prevention and filtration mechanism 2 is arranged between the end ring 16 and the flow end ring 17. The sand prevention and filtration mechanism 2 of the present application is prepared by using a metal filter screen and can prevent formation sand from entering the tool interior.

[0043] The working process of the present application is as follows:

[0044] The completion structure of the present application is arranged in the oil well completion stage. In the normal production of the oil well, under the lifting action of the submersible electric pump, a certain pressure difference is formed between the outside and the inside of the completion pipe string. When the pressure difference between the outside pressure and the inside pressure is less than the opening pressure of the pressure difference self-balancing assembly 14, the movable sliding sleeve 4 is in the initial position as shown in the figure, the flow channel on the center pipe 1 is in the closed state, and the fluid enters the pipe string interior from the sand prevention pipe 13 of the completion pipe string. Figure 7 When the completion pipe string is blocked due to reasons such as the production liquid cannot reach the allocation target, or the large-displacement water flooding production is required after the water content rises in the later production stage, the production pressure difference is increased by controlling the submersible electric pump. When the pressure difference between the outside pressure and the inside pressure of the completion pipe string is greater than the opening pressure of the pressure difference self-balancing assembly 14, the movable sliding sleeve 4 moves to the right under the action of the pressure difference between the inside and the outside and compresses the elastic member 8 (see Figure 8), the flow channel is in the open state, the oil and water flow through the sand prevention filter mechanism 2 into the differential pressure self-balancing assembly 14, pass through the flow hole 5 into the central pipe 1 to be mined out of the well, increase the flow area of the production layer to the inside of the pipe string, and realize the purpose of large liquid production; when it is necessary to reduce liquid production or temporarily stop the well, the production pressure difference is reduced by controlling the submersible electric pump, when the pressure difference between the outside pressure and the inside pressure of the completion pipe string is less than the opening pressure of the differential pressure self-balancing assembly 14, the flow channel is automatically closed, the purpose of low liquid production or stoppage is realized, and the purpose of reducing leakage is realized when the well is stopped; the differential pressure self-balancing continuous injection and production completion structure realizes the repeated self-balancing opening and closing of the flow channel through the pressure difference between the outside and the inside of the pipe string, realizes the balanced control of the production pressure difference and the liquid production, plays the role of low pressure difference stable oil production in the early production stage and large liquid production by releasing the pressure difference in the later production stage, so that the stable oil production and the production effect of taking oil with water are realized. When the oil well needs to be changed into a water injection well, the operation method of not moving the pipe string can be used, the inside of the pipe string is pressed to a certain value at the wellhead, or a special tool is lowered into the position of the differential pressure self-balancing assembly 14 through the coiled tubing (see Figure 9 ), when the inside pressure is greater than the outside pressure and the pressure difference reaches a certain value, the moving sleeve 4 pushes the shear ring 6 to be sheared, the shear ring 6 is sheared to separate into an outer shear fragment 61 and an inner shear fragment 62, the moving sleeve 4 continues to move to the limiting device 3, the locking mechanism 41 of the moving sleeve 4 is locked with the locking groove 31 of the limiting device 3, and the flow channel on the central pipe 1 is opened to the normally open position (see Figure 10 ), the purpose of changing the oil production well into a water injection well is realized, and the injected water enters the formation after passing through the flow hole 5 of the central pipe 1 and the sand prevention filter mechanism 2. While improving the oil production effect and the convenience of the oil well conversion operation, the present application avoids the influence of pump shutdown and well shutdown for workover operation or moving pipe string operation on the electric pump unit, avoids the damage to the reservoir caused by workover, and saves the construction cost.

[0045] The present application also provides an implementation method of the differential pressure self-balancing continuous injection and production, which includes any one of the following:

[0046] a) during normal production, under the lifting action of the submersible electric pump, the flow channel of the differential pressure self-balancing assembly 14 is in the closed state, and the fluid enters the inside of the pipe string from the screen pipe, the perforated pipe or other tools of the completion pipe string;

[0047] b) when the oil well liquid production does not reach the allocation index or liquid production needs to be increased, the production pressure difference is increased by controlling the submersible electric pump, the flow channel is automatically opened, the flow area of the production layer to the inside of the pipe string is increased, and the purpose of large liquid production is realized;

[0048] c) when it is necessary to reduce liquid production or temporarily stop the well, the production pressure difference is reduced by controlling the submersible electric pump, the flow channel is automatically closed, the purpose of low liquid production or stoppage is realized, and the purpose of reducing leakage is realized when the well is stopped.

[0049] d) When the oil well needs to be converted into a water injection well, the wellhead is pressured or a special pipe string is lowered to pressure the inside of the differential pressure self-balancing assembly 14, open the overflow passage to the normally open position, and achieve the purpose of water injection operation.

[0050] The embodiments of the present application are preferred embodiments of the present application, but are not intended to limit the protection scope of the present application, and therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A well completion structure for differential pressure self-balancing continuous injection and production, comprising a wellbore (10), a tubing string (11) provided inside the wellbore (10), and a sand control pipe (13) provided on the tubing string (11), characterized in that: The tubing (11) is also provided with a differential pressure self-balancing assembly (14); the differential pressure self-balancing assembly (14) includes a central tube (1), which has multiple flow holes (5); an outer protective cover (9) is provided outside the central tube (1), and a movable sliding sleeve (4) for opening or closing the flow holes (5) is provided in the cavity between the central tube (1) and the outer protective cover (9), and the movable sliding sleeve (4) is slidably connected to the central tube (1); an elastic element (8) is provided on one side of the movable sliding sleeve (4), and a limiting device (3) is provided on the other side; the differential pressure self-balancing assembly (14) is also provided with a sand-proof filtering mechanism (2). The limiting device (3) is fixed on the central tube (1). The limiting device (3) includes an annular body (33), a locking groove (31) is formed in the middle of the outer wall of the body (33) along the circumferential direction; and an introduction chamfer (32) is formed in the circumferential direction at the edge of the body (33). The movable sliding sleeve (4) includes an annular base (43), and a locking mechanism (41) is provided at intervals on the circumferential surface of one end of the base (43); two sliding sealing rings (42) are provided on the inner wall of the base (43).

2. The well completion structure for differential pressure self-balancing continuous injection and production as described in claim 1, characterized in that: The locking mechanism (41) is a flexible hook.

3. The well completion structure for differential pressure self-balancing continuous injection and production as described in claim 1, characterized in that: The outer wall of the central tube (1) is provided with a base (7), and the elastic element (8) is provided on the base (7).

4. The well completion structure for differential pressure self-balancing continuous injection and production as described in claim 3, characterized in that: A shear groove is formed at one end of the base (7), and a shear ring (6) is fitted inside the shear groove of the base (7).

5. The well completion structure for differential pressure self-balancing continuous injection and production as described in claim 4, characterized in that: The sliding seal ring (42) on the side of the movable sliding sleeve (4) away from the locking mechanism (41) is located between the shear ring (6) and the elastic element (8); the sliding seal ring (42) on the side of the movable sliding sleeve (41) closer to the locking mechanism (41) is located on the central tube (1) in front of the base (7).

6. The well completion structure for pressure differential self-balancing continuous injection and production as described in claim 1, characterized in that: The central tube (1) is also provided with an end ring (16) and a flow end ring (17). The flow end ring (17) is located between the end ring (16) and the outer cover (9), and a through hole is formed between the flow end ring (17) and the central tube (1).

7. The well completion structure for differential pressure self-balancing continuous injection and production as described in claim 6, characterized in that: The sand filter mechanism (2) is located between the end ring (16) and the flow end ring (17).

8. A method for implementing differential pressure self-balancing continuous injection and production, characterized in that: The well completion structure using the differential pressure self-balancing continuous injection and production production method described in any one of claims 1-7 includes any one of the following implementation methods: a. During normal production, under the lifting action of the submersible electric pump, the flow passage of the differential pressure self-balancing component (14) is closed, and the fluid enters the inside of the well string from the screen pipe or perforated pipe of the completion string. b. When the well fluid production does not meet the production target or when it is necessary to increase the fluid production, the production pressure difference is increased by controlling the submersible electric pump. The flow channel of the pressure difference self-balancing component (14) is automatically opened to increase the flow area from the production layer to the inside of the tubing, so as to achieve the purpose of large-volume fluid production. c. When it is necessary to reduce the production volume of liquid or temporarily shut down the well, the production pressure difference is reduced by controlling the submersible electric pump, and the flow channel of the pressure difference self-balancing component (14) is automatically closed to achieve the purpose of reducing leakage by reducing the production volume of liquid or shutting down the well. d. When an oil well needs to be converted into a water injection well, pressurize the wellhead or run a special tubing string inside the differential pressure self-balancing component (14) to open the flow passage to the normally open position and achieve the purpose of water injection operation.

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