Chemical injection production string for oil well

Abstract

The utility model discloses an oil production well dosing production pipe column, which comprises an oil layer casing pipe, a large oil pipe is sleeved in the oil layer casing pipe, a small oil pipe is sleeved in the large oil pipe, a three-way joint is installed at the bottom end of the large oil pipe, an upper sealing insertion pipe is installed at the bottom end of the small oil pipe, a sealing cylinder is installed at the top end of the three-way joint, a lower oil pipe is communicated at the bottom end of the three-way joint, a dosing oil pipe is sleeved in the lower oil pipe, the three-way joint is provided with two independent and up-and-down through flow channels, a lower sealing insertion pipe is connected to the bottom end of the dosing oil pipe, an insertion pipe device is installed on the inner wall of the lower oil pipe, a forward check valve is installed at the bottom end of the insertion pipe device, and a pumping unit is installed in the small oil pipe.

Description

Technical Field

[0001] This utility model relates to the field of oil well production tubing technology, and in particular to an oil well chemical dosing production tubing. Background Technology

[0002] During oil well production, the formation water has complex properties; some is corrosive, some is prone to scaling, and some crude oil has a high wax content, making the tubing prone to wax formation. Usually, it is necessary to add corrosion inhibitors, scale inhibitors, and wax removers and preventers through the annulus. However, when the crude oil has a high wax content and a high pour point, dead oil rings are easily formed in the annulus. The presence of dead oil rings prevents the agents from being added to the well through the annulus, forcing the company to periodically inspect the pump, replace the tubing and sucker rod, etc., which is costly. Utility Model Content

[0003] The purpose of this utility model is to provide a production tubing string for chemical dosing in oil wells. Chemicals are added through the annulus of the large and small tubings. The chemicals are mixed with the produced fluid of the oil layer through the three-pipe joint and the dosing tubing. Then, they enter the small tubing through the lower tubing, the three-pipe joint and the sealing pipe, and are pumped to the surface by the oil pump. This solves the problem that chemicals cannot be added downhole in oil wells with dead oil rings in the annulus of the casing.

[0004] To achieve the objectives of this utility model, a production tubing string for chemical dosing in oil wells is provided, comprising: an oil layer casing, a large oil tubing sleeved inside the oil layer casing, a small oil tubing sleeved inside the large oil tubing, a three-way connector installed at the bottom end of the large oil tubing, an upper sealing insert installed at the bottom end of the small oil tubing, a sealing cylinder installed at the top end of the three-way connector, the bottom end of the upper sealing insert being inserted into and sealed to the sealing cylinder, the small oil tubing being connected to the three-way connector through the insertion structure of the upper sealing insert and the sealing cylinder, and a lower oil tubing connected to the bottom end of the three-way connector. A dosing oil pipe is sleeved inside the lower oil pipe. The three-pipe joint has two independent and vertically connected flow channels. The lower oil pipe is connected to the small oil pipe through one flow channel of the three-pipe joint, and the dosing oil pipe is connected to the annulus between the large and small oil pipes through the other flow channel of the three-pipe joint. A lower sealing insert is connected to the bottom end of the dosing oil pipe. An inserter is installed on the inner wall of the lower oil pipe. The bottom end of the lower sealing insert is inserted and sealed with the inserter. A positive check valve is installed at the bottom end of the inserter. An oil pump is installed inside the small oil pipe.

[0005] As a preferred embodiment of this utility model, the top of the oil pump is connected to a sucker rod.

[0006] As a preferred embodiment of this utility model, the upper sealing tube is a through-tube structure, comprising an upper connector, an intermediate body, a lower connector, and a sealing element. The upper connector, intermediate body, and lower connector are sequentially threaded together. The upper end of the upper connector is threadedly connected to the bottom end of the small oil tube, and the lower end of the upper connector is a small-diameter section used to fit the sealing element. The upper end of the intermediate body is threadedly connected to the bottom end of the upper connector, and the upper surface of the intermediate body presses against the sealing element. The lower end of the intermediate body is a small-diameter section used to fit the sealing element. The upper end of the lower connector is threadedly connected to the lower end of the intermediate body, and the upper surface of the lower connector presses against the sealing element.

[0007] As a preferred embodiment of this utility model, the lower end face of the lower connector is provided with a horseshoe-shaped guide shoe.

[0008] As a preferred technical solution of this utility model, the sealing cylinder is a through-hole structure. The through hole of the sealing cylinder includes a large-diameter section, a small-diameter section and a step. The small-diameter section is located below the large-diameter section, and the top of the small-diameter section transitions to the bottom of the large-diameter section through the step. The bottom end of the upper sealing tube is inserted into the large-diameter section until it abuts against the step. The outer wall of the bottom end of the sealing cylinder is provided with external threads and is threadedly connected to the three-pipe joint.

[0009] As a preferred embodiment of this utility model, the three-pipe connector includes an upper connector and a lower connector. The lower connector is sleeved on the bottom end of the upper connector, forming an annular space between the upper and lower connectors. The top end of the upper connector is provided with a first threaded upper interface, and the top end of the lower connector is provided with a second threaded upper interface. The bottom end of the lower connector is provided with a stepped first threaded lower interface and a second threaded lower interface, and the diameter of the second threaded lower interface is smaller than that of the first threaded lower interface. The lower connector has a central blind hole, an eccentric hole, and a radial through hole vertically formed inside. The eccentric hole and the radial through hole are circumferentially spaced. There are two eccentric holes. The two ends of the eccentric hole connect the second threaded upper interface and the first threaded lower interface. The top end of the annular space of the upper connector connects to the first threaded upper interface. The bottom end of the central blind hole connects to the second threaded lower interface. The two ends of the radial through hole connect the central blind hole and the annular space of the upper connector.

[0010] As a preferred embodiment of this utility model, the first threaded upper interface is threadedly connected to the large oil pipe, the second threaded lower interface is threadedly connected to the chemical injection oil pipe, and the chemical injection oil pipe is connected to the annulus between the large oil pipe and the small oil pipe through the flow channel of the central blind hole, radial perforation and upper connector annulus.

[0011] As a preferred embodiment of this utility model, the second threaded upper interface is threadedly connected to the sealing cylinder, the first threaded lower interface is threadedly connected to the lower oil pipe, and the lower oil pipe is connected to the sealing cylinder through the flow channel of the eccentric hole.

[0012] As a preferred embodiment of this utility model, a plug is installed at the bottom end of the lower oil pipe, and a lower screen pipe is installed between the plug and the positive flow valve.

[0013] As a preferred embodiment of this utility model, an upper screen tube is installed between the cannula and the three-tube connector, and the upper screen tube is sleeved on the dosing oil tube.

[0014] Compared with the prior art, this utility model provides a production tubing string for chemical dosing in oil wells, which has the following beneficial effects:

[0015] This invention utilizes annular dosing via large and small tubing. The reagent mixes with the produced fluid from the oil layer through a three-pipe joint and the dosing tubing, then enters the small tubing via the lower tubing, the three-pipe joint, and a sealed insert, and is pumped to the surface by a pump. This solves the problem of reagents not being able to be added downhole in wells with dead oil rings in the annulus. The dosing path is as follows: the reagent enters the upper joint annulus through the annulus between the large and small tubings, and then enters the dosing tubing through radial perforations and a central blind hole channel. The oil discharge path is as follows: after mixing with the produced fluid from the oil layer, the reagent enters the eccentric hole channel through the lower tubing, and then enters the small tubing through a sealed cylinder and an upper sealed insert, and is pumped to the surface by a pump. The same path can also be used to achieve reverse circulation well washing. Since the two channels in the three-pipe joint are independent of each other, and during normal production, due to the forward flow valve structure and the dual-channel structure of the three-pipe joint, the crude oil produced from the formation cannot enter the annulus of the large and small oil pipes through the three-pipe joint, and a dead oil ring will not be formed in the annulus of the large and small oil pipes. This greatly extends the operation of pump inspection, oil pipe replacement, sucker rod replacement, etc., and reduces production costs. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the upper sealing insertion tube structure of this utility model;

[0018] Figure 3 This is a schematic diagram of the sealing cylinder structure of this utility model;

[0019] Figure 4 This is a schematic diagram of the three-pipe connector structure of this utility model;

[0020] Figure 5 This is a schematic diagram of the radial cross-sectional structure of the three-pipe connector of this utility model.

[0021] 1 is the oil layer casing, 2 is the large oil pipe, 3 is the small oil pipe, 4 is the three-pipe joint, 5 is the upper sealing insert, 6 is the sealing cylinder, 7 is the lower oil pipe, 8 is the chemical dosing oil pipe, 9 is the lower sealing insert, 10 is the inserter, 11 is the positive check valve, 12 is the oil pump, 13 is the upper joint, 14 is the intermediate body, 15 is the lower joint, 16 is the seal, 17 is the horseshoe-shaped guide shoe, 18 is the large diameter section, 19 is the small diameter section, 20 is the step, 21 is the upper joint, 22 is the lower joint, 23 is the upper joint annulus, 24 is the first thread upper interface, 25 is the second thread upper interface, 26 is the first thread lower interface, 27 is the second thread lower interface, 28 is the central blind hole, 29 is the eccentric hole, 30 is the radial perforation, 31 is the lower screen pipe, 32 is the plug, 33 is the upper screen pipe, 34 is the oil layer, and 35 is the dead oil ring. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Please see Figures 1-5 This utility model provides a production tubing string for chemical dosing in an oil well, comprising: an oil layer casing 1, a large oil pipe 2 sleeved inside the oil layer casing 1, a small oil pipe 3 sleeved inside the large oil pipe 2, a three-way connector 4 installed at the bottom end of the large oil pipe 2, an upper sealing insert 5 installed at the bottom end of the small oil pipe 3, a sealing cylinder 6 installed at the top end of the three-way connector 4, the bottom end of the upper sealing insert 5 being inserted and sealed to the sealing cylinder 6, the small oil pipe 3 being connected to the three-way connector 4 through the insertion structure of the upper sealing insert 5 and the sealing cylinder 6, and a lower oil pipe 7 connected to the bottom end of the three-way connector 4. The inner sleeve is fitted with a dosing oil pipe 8. The three-pipe joint 4 is provided with two independent and vertically connected flow channels. The lower oil pipe 7 is connected to the small oil pipe 3 through one flow channel of the three-pipe joint 4. The dosing oil pipe 8 is connected to the annulus between the large oil pipe 2 and the small oil pipe 3 through the other flow channel of the three-pipe joint 4. The bottom end of the dosing oil pipe 8 is connected to a lower sealing insert 9. An inserter 10 is installed on the inner wall of the lower oil pipe 7. The bottom end of the lower sealing insert 9 is inserted and sealed with the inserter 10. A positive flow valve 11 is installed at the bottom end of the inserter 10. An oil pump 12 is installed inside the small oil pipe 3.

[0024] In one embodiment of the present invention, the top of the oil pump 12 is connected to a sucker rod.

[0025] In one embodiment of this utility model, the upper sealing tube 5 is a through-tube structure and includes an upper connector 13, an intermediate body 14, a lower connector 15, and a sealing element 16. The upper connector 13, the intermediate body 14, and the lower connector 15 are sequentially threaded together. The upper end of the upper connector 13 is threadedly connected to the bottom end of the small oil tube 3. The lower end of the upper connector 13 is a small-diameter section used to fit the sealing element 16. The upper end of the intermediate body 14 is threadedly connected to the bottom end of the upper connector 13, and the upper end face of the intermediate body 14 presses against the sealing element 16. The lower end of the intermediate body 14 is a small-diameter section used to fit the sealing element 16. The upper end of the lower connector 15 is threadedly connected to the lower end of the intermediate body 14, and the upper end face of the lower connector 15 presses against the sealing element 16.

[0026] In one embodiment of this utility model, the lower end face of the lower connector 15 is provided with a horseshoe-shaped guide shoe 17.

[0027] In one embodiment of this utility model, the sealing cylinder 6 is a through-hole structure. The through hole of the sealing cylinder 6 includes a large diameter section 18, a small diameter section 19, and a step 20. The small diameter section 19 is located below the large diameter section 18, and the top of the small diameter section 19 transitions to the bottom of the large diameter section 18 through the step 20. The bottom end of the upper sealing tube 5 is inserted into the large diameter section 18 until it abuts against the step 20. The outer wall of the bottom end of the sealing cylinder 6 is provided with external threads and is threadedly connected to the three-pipe connector 4.

[0028] In one embodiment of this utility model, the three-pipe connector 4 includes an upper connector 21 and a lower connector 22. The lower connector 22 is sleeved on the bottom end of the upper connector 21, and an upper connector annular space 23 is formed between the upper connector 21 and the lower connector 22. The top end of the upper connector 21 is provided with a first threaded upper interface 24, and the top end of the lower connector 22 is provided with a second threaded upper interface 25. The bottom end of the lower connector 22 is provided with a first threaded lower interface 26 and a second threaded lower interface 27 in a stepped manner, and the diameter of the second threaded lower interface 27 is smaller than that of the first threaded lower interface. 26. The lower connector 22 is vertically provided with a central blind hole 28, an eccentric hole 29 and a radial through hole 30. The eccentric holes 29 and the radial through holes 30 are circumferentially spaced. There are two eccentric holes 29. The two ends of the eccentric holes 29 are connected to the second threaded upper interface 25 and the first threaded lower interface 26. The top end of the upper connector annular space 23 is connected to the first threaded upper interface 24. The bottom end of the central blind hole 28 is connected to the second threaded lower interface 27. The two ends of the radial through hole 30 are connected to the central blind hole 28 and the upper connector annular space 23.

[0029] In one embodiment of this utility model, the first threaded upper interface 24 is threadedly connected to the large oil pipe 2, and the second threaded lower interface 27 is threadedly connected to the chemical dosing oil pipe 8. The chemical dosing oil pipe 8 is connected to the annulus between the large oil pipe 2 and the small oil pipe 3 through the flow channels of the central blind hole 28, the radial through hole 30 and the upper connector annulus 23.

[0030] In one embodiment of this utility model, the second threaded upper interface 25 is threadedly connected to the sealing cylinder 6, and the first threaded lower interface 26 is threadedly connected to the lower oil pipe 7. The lower oil pipe 7 is connected to the sealing cylinder 6 through the flow channel of the eccentric hole 29.

[0031] In one embodiment of this utility model, a plug 32 is installed at the bottom end of the lower oil pipe 7, and a lower screen pipe 31 is installed between the plug 32 and the positive flow valve 11.

[0032] In one embodiment of this utility model, an upper screen tube 33 is installed between the cannula 10 and the three-pipe connector 4, and the upper screen tube 33 is sleeved on the dosing oil pipe 8.

[0033] The above are merely preferred embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this utility model, based on the technical solution and inventive concept of this utility model, should be included within the scope of protection of this utility model.

Claims

1. A production tubing string for chemical dosing in oil wells, characterized in that, include: An oil layer casing (1) is fitted with a large oil pipe (2), and a small oil pipe (3) is fitted inside the large oil pipe (2). A three-pipe connector (4) is installed at the bottom end of the large oil pipe (2), and an upper sealing insert (5) is installed at the bottom end of the small oil pipe (3). A sealing cylinder (6) is installed at the top end of the three-pipe connector (4). The bottom end of the upper sealing insert (5) is inserted and sealed to the sealing cylinder (6). The small oil pipe (3) is connected to the three-pipe connector (4) through the insertion structure of the upper sealing insert (5) and the sealing cylinder (6). A lower oil pipe (7) is connected to the bottom end of the three-pipe connector (4). A chemical dosing pipe (8) is fitted inside the lower oil pipe (7). The three-pipe connector (4) is provided with two independent and vertically connected flow channels. The lower oil pipe (7) is connected to the small oil pipe (3) through one flow channel of the three-pipe connector (4). The dosing oil pipe (8) is connected to the annulus between the large oil pipe (2) and the small oil pipe (3) through the other flow channel of the three-pipe connector (4). The bottom end of the dosing oil pipe (8) is connected to a lower sealing insert (9). An inserter (10) is installed on the inner wall of the lower oil pipe (7). The bottom end of the lower sealing insert (9) is inserted and sealed with the inserter (10). A positive flow valve (11) is installed at the bottom end of the inserter (10). An oil pump (12) is installed inside the small oil pipe (3).

2. The production tubing string for chemical dosing in oil wells according to claim 1, characterized in that: The top of the oil pump (12) is connected to a sucker rod.

3. The production tubing string for chemical dosing in oil wells according to claim 1, characterized in that: The upper sealing tube (5) is a through tube structure and includes an upper connector (13), an intermediate body (14), a lower connector (15), and a seal (16). The upper connector (13), the intermediate body (14), and the lower connector (15) are connected by threads in sequence. The upper end of the upper connector (13) is threaded to the bottom end of the small oil tube (3). The lower end of the upper connector (13) is set as a small diameter section, which is used to fit the seal (16). The upper end of the intermediate body (14) is threaded to the bottom end of the upper connector (13), and the upper end face of the intermediate body (14) is pressed against the seal (16). The lower end of the intermediate body (14) is set as a small diameter section, which is used to fit the seal (16). The upper end of the lower connector (15) is threaded to the lower end of the intermediate body (14), and the upper end face of the lower connector (15) is pressed against the seal (16).

4. The production tubing string for chemical dosing in oil wells according to claim 3, characterized in that: The lower end face of the lower connector (15) is provided with a horseshoe-shaped guide shoe (17).

5. The production tubing string for chemical dosing in oil wells according to claim 1, characterized in that: The sealing cylinder (6) is a through-hole structure. The through hole of the sealing cylinder (6) includes a large diameter section (18), a small diameter section (19) and a step (20). The small diameter section (19) is located below the large diameter section (18), and the top of the small diameter section (19) transitions to the bottom of the large diameter section (18) through the step (20). The bottom end of the upper sealing tube (5) is inserted into the large diameter section (18) until it reaches the step (20). The outer wall of the bottom end of the sealing cylinder (6) is provided with external threads and is threadedly connected to the three-pipe connector (4).

6. The production tubing string for chemical dosing in oil wells according to claim 1, characterized in that: The three-pipe connector (4) includes an upper connector (21) and a lower connector (22). The lower connector (22) is fitted onto the bottom end of the upper connector (21), and an annular space (23) is formed between the upper connector (21) and the lower connector (22). The upper connector (21) has a first threaded upper interface (24) at its top end, and the lower connector (22) has a second threaded upper interface (25) at its top end. The lower connector (22) has a first threaded lower interface (26) and a second threaded lower interface (27) at its bottom end in a stepped configuration. The diameter of the second threaded lower interface (27) is smaller than that of the first threaded lower interface (26). The lower connector (22) is vertically provided with a central blind hole (28), an eccentric hole (29) and a radial through hole (30). The eccentric hole (29) and the radial through hole (30) are circumferentially spaced. There are two eccentric holes (29). The two ends of the eccentric hole (29) are connected to the second threaded upper interface (25) and the first threaded lower interface (26). The top end of the upper connector annular space (23) is connected to the first threaded upper interface (24). The bottom end of the central blind hole (28) is connected to the second threaded lower interface (27). The two ends of the radial through hole (30) are connected to the central blind hole (28) and the upper connector annular space (23).

7. The production tubing string for chemical dosing in oil wells according to claim 6, characterized in that: The first threaded upper interface (24) is threadedly connected to the large oil pipe (2), and the second threaded lower interface (27) is threadedly connected to the drug-adding oil pipe (8). The drug-adding oil pipe (8) is connected to the annulus between the large oil pipe (2) and the small oil pipe (3) through the flow channels of the central blind hole (28), the radial through hole (30) and the upper connector annulus (23).

8. The production tubing string for chemical dosing in oil wells according to claim 6, characterized in that: The second threaded upper interface (25) is threadedly connected to the sealing cylinder (6), and the first threaded lower interface (26) is threadedly connected to the lower oil pipe (7). The lower oil pipe (7) is connected to the sealing cylinder (6) through the flow channel of the eccentric hole (29).

9. The production tubing string for chemical dosing in oil wells according to claim 1, characterized in that: A plug (32) is installed at the bottom of the lower oil pipe (7), and a lower screen pipe (31) is installed between the plug (32) and the positive flow valve (11).

10. The production tubing string for chemical dosing in oil wells according to claim 1, characterized in that: An upper screen tube (33) is installed between the cannula (10) and the three-pipe connector (4), and the upper screen tube (33) is sleeved on the dosing oil tube (8).

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