Horizontal well reverse circulation continuous sand washing method

Abstract

The invention belongs to the technical field of petroleum workover treatment, and discloses a reverse circulation continuous sand washing method for a horizontal well. By means of the reversing pup joint, in the running-in process of sand washing operation, a lateral channel of the reversing pup joint is closed, a bridge type channel is communicated, and sand washing liquid enters a well from an oil sleeve annulus, passes through the bridge type channel of the reversing pup joint from an oil pipe and flows out of the well from a faucet; in the process of changing a single pipe in sand washing operation, a lateral channel of the reversing pup joint is opened, and sand washing liquid enters a well from an oil sleeve annulus, passes through a lateral opening of the reversing pup joint from an oil pipe and flows out of the well from a lateral opening of the well mouth sealing device.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum well repair operations, and in particular relates to a horizontal well reverse circulation continuous sand flushing method. Background Art

[0002] In the process of developing low-permeability and ultra-low-permeability reservoirs in domestic and foreign oil fields, horizontal well production technology can effectively improve the recovery rate, and the implementation effect is remarkable. It is an important process technology for oil field development. In the process of horizontal well production, affected by factors such as drainage method and production pressure difference, the sand production phenomenon of horizontal wellbore is becoming more and more serious. After a period of production, it is easy to cause sand burial in horizontal well section or deflection well section, which may affect production at the least, or jam the production pipe string or tool at the worst. It is the main reason for the shutdown, overhaul or scrapping of horizontal wells. At present, foreign horizontal wells mostly choose continuous tubing to operate on the sand flushing pipe string to ensure the continuous circulation of sand flushing fluid, thereby achieving efficient and safe sand flushing effect. For my country, the cost of using continuous tubing is relatively high, and it faces the problems of complex geological conditions and scattered distribution of oil wells. Some wells are not only scattered in urban areas, but also in environmental protection areas. The particularity of the well location brings difficulties to continuous tubing operations. Moreover, most horizontal wells are production wells, with few water injection wells and an imperfect well network. Long-term exploitation leads to decreased formation energy and low pressure, resulting in serious leakage during sand flushing operations, and even the inability to establish a circulation of sand flushing fluid.

[0003] The prior art has adopted a variety of reverse circulation continuous sand flushing devices, which can make it possible to flush sand without stopping the pump when a single root is flushed, prevent sand from accumulating, and do not need to re-establish the circulation.

[0004] Chinese patent application 2010101110614.7 "Horizontal Well Continuous Sand Flushing Device", the invention of the reversing valve is composed of a reversing valve housing, a valve core, a valve seat, a spring, a sliding valve, and a sliding valve top claw. The reversing valve housing is in a closed three-way housing, and the upper sealing rubber and the lower sealing rubber wrap the reversing valve housing. There is a connecting hole on the reversing valve housing. When the oil pipe is connected, the connecting hole is between the upper sealing rubber and the lower sealing rubber. The lower part of the reversing valve housing is connected to the oil pipe. The valve core, valve seat, spring, sliding valve, and sliding valve top claw are installed in the reversing valve housing. The valve core is connected to the valve seat, and the valve seat is fixed in the reversing valve housing. The valve core penetrates into the sliding valve and cooperates with the inner shoulder of the sliding valve to seal. The sliding valve is supported by a spring. The upper part of the sliding valve has The sliding valve top claw and the sliding valve can slide in the reversing valve housing to open or close the connecting hole. When the short section is connected to the reversing valve housing, the short section presses down the sliding valve top claw and the sliding valve, and the sliding valve moves down to close the connecting hole. When the oil pipe goes down during sand flushing, the sand flushing liquid enters the casing from the large four-way and returns upward from the oil pipe after carrying sand. After one oil pipe is completely lowered into the casing, the reversing valve housing on the other oil pipe enters the closed three-way housing, and the connecting hole is between the upper sealing rubber and the lower sealing rubber. The short section is removed, and the short section loses the constraint on the sliding valve top claw. The spring supports the sliding valve to move upward, the valve core and the inner shoulder of the sliding valve cooperate to seal, and the connecting holes are opened at the same time. The sand flushing liquid enters the casing from the large four-way and returns upward from the oil pipe after carrying sand, and flows out through the three-way outlet.

[0005] Chinese patent application 201410591540.1 "Continuous sand flushing conversion tool", the invention of the oil pipe reversing joint assembly includes a coupling, an outer pipe, a positioning pin, an outer pipe bypass, a top valve core, a valve core upper bypass, a positioning groove, a sealing key groove, a sealing ring, a lower bypass, a spring, a switch control valve, and a connecting thread upper shackle. The upper end of the outer pipe is connected to the switch control valve through a coupling, and a connecting thread upper shackle is arranged inside the switch control valve. The top valve core is hollowly sleeved inside the outer pipe, and the upper end of the top valve core is connected to the switch control valve. An upper bypass and a lower bypass are respectively provided on the top valve core, a positioning groove and a sealing key groove are also provided on the outer wall of the top valve core at a position between the upper bypass and the lower bypass of the valve core, a positioning pin is provided on the outer tube corresponding to the position of the positioning groove, and an outer tube bypass is also provided on the outer tube, a spring is provided between the bottom of the top valve core and the inner circular ring platform at the bottom of the outer tube, and the pump does not need to be stopped when connecting a single root. When the wellhead top valve is removed, the upper circulation channel controlled by the thread is closed, and another circulation channel is opened at the same time, so that the sand flushing fluid channel is instantly converted.

[0006] Chinese patent application 201721229377.X "A continuous reverse sand flushing device for oil wells" discloses a continuous sand flushing conversion joint comprising a coupling, a short joint, a body, a sand flushing control valve, a spring, a sealing ball, and a lower joint; the lower end of the coupling is sequentially connected to the short joint, the sand flushing control valve, the body, and the lower joint, and an inverted L-shaped check valve cavity is provided from the lower center to the circumference of the body, the upper diameter of the inverted L-shaped check valve cavity is smaller than the lower diameter, and a check valve seat is provided at the bottom of the inverted L-shaped check valve cavity, and a check valve seat is provided on the check valve seat. A sealing ball is provided, and a spring is provided between the sealing ball and the reducing step. When connecting a single root, first close the upper sand flushing control valve of the continuous sand flushing conversion joint, cut off the sand flushing liquid, remove the faucet, and then connect the faucet with the subsequent continuous sand flushing conversion joint, and connect the subsequent continuous sand flushing conversion joint with the oil pipe. At this time, open the upper ball valve of the subsequent continuous sand flushing conversion joint, lift it with an elevator, and then connect the oil pipe with the continuous sand flushing conversion joint. After the connection is completed, open the upper sand flushing control valve of the continuous sand flushing conversion joint to continue sand flushing.

[0007] Chinese patent application 201320266699.7 "A horizontal well continuous reverse circulation sand flushing device" discloses a three-way ball valve conversion device consisting of an upper joint, a reversing valve body and a three-way valve assembly; the upper end of the reversing valve body is connected to the upper joint, a beveled shoulder is provided inside the reversing valve body, and the three-way valve assembly is placed inside the reversing valve body and sits on the beveled shoulder; the three-way valve assembly includes a three-way ball valve body, a three-way ball core and a ball valve seat, a T-shaped cylindrical channel is provided on the three-way ball valve body, and a ball valve seat is provided on the three-way ball valve body. The valve seat and the three-way ball core are provided with a cylindrical channel and can cooperate with the cylindrical channel of the three-way ball valve body. The three-way ball core is in contact with the ball valve seat. The docking pin passes through the three-way ball valve body and is connected to the three-way ball core's docking pin groove fixing bolt. The three-way ball core can rotate along the axis of the docking pin; the lower outer wall of the three-way ball valve body and the lower inner wall of the reversing valve body form an annular space, and the bypass of the T-shaped cylindrical channel of the three-way ball valve body is connected to the annular space, and the annular space is connected to the outside through the connecting hole at the bottom of the reversing valve body. When connecting a single root, use an external rotary wrench to rotate 90 degrees, which can realize linear travel adjustment and spherical rotation adjustment to change the direction of the T-shaped cylindrical channel of the three-way ball core 6, so as to change the flow direction of the sand flushing liquid and realize the confluence and separation of the sand flushing liquid.

[0008] The above technologies cannot realize the automatic redirection of the return liquid, cannot fully realize the purpose of continuous sand flushing, and cannot achieve the ideal effect. Summary of the invention

[0009] In order to overcome the deficiencies of the prior art, the present invention provides a horizontal well reverse circulation continuous sand flushing method, which realizes automatic reversal of return fluid during reverse circulation sand flushing operation, and can effectively solve the problem of low efficiency of horizontal well sand flushing operation and re-establishing circulation.

[0010] The above object of the present invention is achieved through the following technical scheme: A horizontal well reverse circulation continuous sand flushing method, the steps are:

[0011] S1. Place a sealing rubber tube at the location of the tubing hanger in the wellhead spool to be sand flushed, and fix the sealing rubber tube in the wellhead spool by means of a top screw;

[0012] S2. The wellhead sealing device is installed on the wellhead spool through a flange connection; the wellhead sealing device contains a sealing rubber cylinder, which can cooperate with the sealing rubber cylinder installed in step S1 to form a closed space;

[0013] S3. Put the sand flushing string into the well; the sand flushing string is composed of the sand flushing pen tip, cyclone sand flusher and oil pipe from bottom to top; the cyclone sand flusher can rotate and stir the accumulated sand at the bottom of the casing to suspend and flush it away, and at the same time, through the throttling speed increase and throttling pressure increase of the spiral groove, a high-speed rotating water flow is formed to improve the flushing and sand carrying capacity of the sand flushing fluid, and the sand deposited at the bottom of the casing is completely removed;

[0014] S4. Connect the oil pipe and lower it into the sand flushing pipe column; when the sand flushing pen tip touches the sand surface, lift up one oil pipe, which is recorded as the first oil pipe;

[0015] S5. Connect the sand flushing pipeline and equipment; the side port of the wellhead four-way is connected to the sand flushing vehicle through a pipeline; the side port of the wellhead four-way is the liquid inlet;

[0016] S6. Connect the first reversing short-circuit lower joint to the upper end of the first oil pipe; connect the reversing short-circuit upper joint to the faucet;

[0017] S7. Connect the side port and the faucet of the wellhead sealing device to the ground three-way valve through pipelines, and connect the ground three-way valve to the sand flushing vehicle through pipelines; the ground three-way valve can collect the return fluids from different outlets into the sand flushing vehicle;

[0018] S8. Start the sand washing treatment vehicle and establish a sand washing cycle;

[0019] S9. Lower the pipe string to perform sand flushing operation; when the reversing short-circuit does not enter the wellhead sealing device, the sand flushing fluid returns to the sand flushing vehicle through the bridge channel of the reversing short-circuit through the faucet; when the reversing short-circuit enters the wellhead sealing device, the sliding sleeve is opened by the clamping action of the installed sealing rubber tube, and the sand flushing fluid returns to the sand flushing vehicle through the lateral channel of the reversing short-circuit; after the reversing short-circuit passes through the wellhead sealing device, the sliding sleeve of the reversing short joint is reset under the action of the spring, and the sand flushing fluid returns to the sand flushing vehicle through the bridge channel of the reversing short-circuit through the faucet;

[0020] S10. When the sand flushing footage of the first tubing is completed, the elevator is used to sit at the wellhead; at this time, the first reversing nipple connected to the first tubing just enters the wellhead sealing device, and the sliding sleeve is opened under the clamping force of the sealing rubber tube, and the return fluid is returned to the sand flushing processing vehicle through the lateral channel of the reversing nipple; remove the faucet at the upper end;

[0021] S11. The second reversing short-circuit lower joint is connected to the upper end of the second oil pipe; the second reversing short-circuit upper joint is connected to the faucet; the lower end of the second oil pipe is connected to the first reversing short-circuit upper joint; the pipe string is lowered to continue the sand flushing operation;

[0022] S12. Repeat steps S9-S11 until the sand is flushed to the designed depth. When the sand content at the outlet is less than 0.2%, lift the pipe string to the vertical well section. After 4 hours, re-explore the sand surface. When the sand surface depth reaches the designed requirement, pull out the sand flushing pipe string.

[0023] Compared with the prior art, the present invention has the following beneficial effects: the present invention utilizes a reversing short-circuit, and during the lowering process of the sand flushing operation, the lateral channel of the reversing short-circuit is closed, the bridge channel is connected, and the sand flushing fluid enters the well from the annulus of the oil casing, and exits the well from the faucet through the bridge channel of the reversing short-circuit from the oil pipe; during the single-root sand flushing operation, the lateral channel of the reversing short-circuit is opened, and the sand flushing fluid enters the well from the annulus of the oil casing, and exits the well from the side port of the wellhead sealing device through the side port of the reversing short-circuit. The switching of the surface return liquid flow channel is completed by a three-way valve. Compared with the prior art, the present invention can realize automatic reversal of the return liquid from the wellhead, without relying on other redundant steps to control the conversion of the liquid flow channel, and has the advantages of connecting a single root without stopping the pump, high operation efficiency, and low sand jam accident rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0025] Figure 1 This is a schematic diagram of sand flushing in reverse circulation continuous sand flushing operation of horizontal wells;

[0026] Figure 2 This is a schematic diagram of a single-joint connection for reverse circulation continuous sand flushing operation in a horizontal well;

[0027] Figure 3 It is a schematic diagram of the reversing short-circuit sealing device for reverse circulation continuous sand flushing operation in horizontal wells;

[0028] Figure 4 It is a schematic diagram of commutation short circuit;

[0029] Figure 5 It is a schematic diagram of the commutation principle of short-circuit commutation.

[0030] In the figure, 1. sand blasting pen tip; 2. cyclone sand blasting device; 3. oil pipe; 4. wellhead four-way; 5. wellhead sealing device; 6. oil pipe coupling; 7. reversing short circuit; 8. faucet; 9. ground three-way valve; 10. sand blasting treatment vehicle; 11. wellhead elevator; 12. upper joint; 13. center pipe; 14. spring seat; 15. spring; 16. sliding sleeve; 17. thread plug; 18. lower joint; 19. bridge channel; 20. side channel; 21. shell; 22. sealing rubber cylinder; 23. wellhead four-way sealing rubber cylinder; 24. side port of wellhead sealing device; 25. side port of wellhead four-way; 26. sand surface. DETAILED DESCRIPTION

[0031] The present invention is described in detail below by specific examples, but the protection scope of the present invention is not limited. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can be obtained from commercial channels.

[0032] Example 1

[0033] like Figure 1 — Figure 5 As shown,

[0034] A horizontal well reverse circulation continuous sand flushing method comprises the following steps:

[0035] Step 1, placing a wellhead spool sealant 23 at the position of the oil pipe hanger in the wellhead spool 4 of the well to be sand flushed, and fixing the wellhead spool sealant 23 in the wellhead spool 4 by means of a jackscrew;

[0036] Step 2, install the wellhead sealing device 5 on the wellhead spool 4 through a flange connection; the wellhead sealing device 5 has a height of 450 mm, a shell 21 with an outer diameter of 230 mm, contains a sealing rubber cylinder 22, and has a sealing pressure of 7 MPa, which can cooperate with the wellhead spool sealing rubber cylinder 23 installed in step 1 to form a closed space;

[0037] Step 3, lowering a sand flushing string into the well; the sand flushing string from bottom to top comprises a sand flushing pen tip 1, a cyclone sand flusher 2, and an oil pipe 3; the cyclone sand flusher 2 has a maximum outer diameter of 116 mm, and can rotate and stir the accumulated sand at the bottom of the casing to suspend and flush it away, while forming a high-speed rotating water flow through the throttling speed increase and throttling pressure increase of the spiral groove, thereby improving the flushing and sand carrying capacity of the sand flushing fluid and completely removing the sediment at the bottom of the casing;

[0038] Step 4, connect the oil pipe and lower it into the sand flushing pipe column; when the sand flushing pen tip 1 touches the sand surface, lift up one oil pipe, which is recorded as the first oil pipe;

[0039] Step 5, connect the sand flushing pipeline and the equipment; the wellhead four-way side port 25 is connected to the sand flushing treatment vehicle 10 through a pipeline; the wellhead four-way side port 25 is a liquid inlet;

[0040] Step 6, the first reversing short-circuit lower connector 18 is connected to the upper end of the first oil pipe; the reversing short-circuit upper connector 12 is connected to the faucet 8;

[0041] Step 7, the side port 24 of the wellhead sealing device and the faucet 8 are connected to the ground three-way valve 9 through pipelines, and the ground three-way valve 9 is connected to the sand flushing vehicle 10 through pipelines; the ground three-way valve 9 can collect the return liquid flowing out of different outlets into the sand flushing vehicle;

[0042] Step 8, start the sand flushing treatment vehicle 10 to establish a sand flushing cycle;

[0043] Step 9, lowering the pipe string for sand flushing operation; when the reversing short circuit 7 does not enter the wellhead sealing device 5, the sand flushing liquid returns to the sand flushing vehicle 10 through the faucet 8 via the bridge channel 19 of the reversing short circuit; when the reversing short circuit 7 enters the wellhead sealing device 5, the sliding sleeve 16 is opened by the clamping action of the installed sealing rubber cylinder 22, and the sand flushing liquid returns to the sand flushing vehicle 10 via the lateral channel 20 of the reversing short circuit; after the reversing short circuit 7 passes through the wellhead sealing device 5, the sliding sleeve 16 of the reversing short section is reset under the action of the spring 15, and the sand flushing liquid returns to the sand flushing vehicle 10 via the bridge channel 19 of the reversing short circuit through the faucet;

[0044] Step 10, when the sand flushing footage of the first oil pipe is completed, the elevator 11 is used to sit on the wellhead; at this time, the first reversing nipple 7 connected to the first oil pipe just enters the wellhead sealing device 5, and the sliding sleeve 16 is opened under the clamping force of the sealing rubber cylinder 22, and the return fluid is returned to the sand flushing processing vehicle 10 through the lateral channel 20 of the reversing nipple; remove the faucet 8 at the upper end;

[0045] Step 11, the second reversing short-circuit lower joint 18 is connected to the upper end of the second oil pipe; the second reversing short-circuit upper joint 12 is connected to the faucet 8; the lower end of the second oil pipe is connected to the first reversing short-circuit upper joint 12; the pipe string is lowered to continue the sand flushing operation;

[0046] Step 12, repeat steps 9-11 until the sand is flushed to the designed depth. When the sand content at the outlet is less than 0.2%, lift the pipe string to the vertical well section. After 4 hours, re-explore the sand surface. When the sand surface depth reaches the designed requirement, pull out the sand flushing pipe string.

[0047] The above-described embodiments are only preferred embodiments of the present invention, but not all feasible embodiments of the present invention. For those skilled in the art, any obvious changes made thereto without departing from the principles and spirit of the present invention should be considered to be included in the scope of protection of the claims of the present invention.

Claims

1. A horizontal well reverse circulation continuous sand flushing method, It is characterized in that The steps are: S1. Place the wellhead spool sealant (23) in the wellhead spool where the tubing is hung, and fix the wellhead spool sealant (23) in the wellhead spool (4) by the top screw; S2. The wellhead sealing device (5) is installed on the wellhead spool (4) through a flange connection; S3. Run the sand flushing string into the well; S4. Connect the oil pipe to the sand flushing column; when the sand flushing pen tip (1) contacts the sand surface (26), lift one oil pipe (3), which is recorded as the first oil pipe (3); S5 connects the sand flushing pipeline and equipment; the wellhead four-way side port (26) and the sand flushing treatment vehicle (10) are connected by a pipeline; the wellhead four-way side port (25) is the liquid inlet; S6. The first reversing short circuit (7) lower connector (18) is connected to the upper end of the first oil pipe (3); the reversing short circuit (7) upper connector (12) is connected to the faucet (8); S7. Connect the side port (24) of the wellhead sealing device and the faucet (8) to the ground three-way valve (9) through pipelines, and connect the ground three-way valve (9) to the sand flushing vehicle (10) through pipelines; the ground three-way valve (9) can collect the return liquid flowing out of different outlets into the sand flushing vehicle (10); S8. Start the sand washing treatment vehicle (10) to establish a sand washing cycle; S9. Lower the pipe string to carry out sand flushing operation; S10. When the sand flushing footage of the first oil pipe is completed, the elevator is used to sit on the wellhead; at this time, the first reversing nipple connected to the first oil pipe (3) just enters the wellhead sealing device (5), and the sleeve (16) is opened under the clamping force of the sealing rubber cylinder (22), and the return fluid is returned to the sand flushing treatment vehicle (10) through the lateral channel (20) of the reversing nipple; remove the faucet (8) at the upper end; S11. The lower joint (18) of the second reversing short circuit (7) is connected to the upper end of the second oil pipe (3); the upper joint (12) of the second reversing short circuit (7) is connected to the faucet (8); the lower end of the second oil pipe (3) is connected to the upper joint (12) of the first reversing short circuit (7); the pipe string is lowered to continue the sand flushing operation; S12. Repeat steps S9-S11 until the sand is flushed to the designed depth. When the sand content at the outlet is less than 0.2%, lift the pipe string to the vertical well section. After 4 hours, re-explore the sand surface (26). When the depth of the sand surface (26) reaches the designed requirement, pull out the sand flushing pipe string.

2. The horizontal well reverse circulation continuous sand flushing method according to claim 1, It is characterized in that The wellhead sealing device (5) in step S2 contains a sealing rubber cylinder (22) which can cooperate with the wellhead four-way sealing rubber cylinder (23) installed in step S1 to form a closed space.

3. The horizontal well reverse circulation continuous sand flushing method according to claim 1, It is characterized in that In step S3, the sand flushing pipe column comprises, from bottom to top, a sand flushing pen tip (1), a cyclone sand flushing device (2), and an oil pipe (3); the cyclone sand flushing device (2) can rotate and stir the accumulated sand at the bottom of the casing to suspend and flush it away, and at the same time, through the throttling speed increase and throttling pressure increase effect of the spiral groove, a high-speed rotating water flow is formed to improve the flushing and sand carrying capacity of the sand flushing liquid, and the sand deposited at the bottom of the casing is completely removed.

4. The horizontal well reverse circulation continuous sand flushing method according to claim 1, It is characterized in that The step S9 specifically comprises: when the reversing short circuit (7) has not entered the wellhead sealing device (5), the sand flushing liquid returns to the sand flushing vehicle (10) through the bridge channel (19) of the reversing short circuit (7) and the faucet (8); when the reversing short circuit (7) enters the wellhead sealing device (5), the sliding sleeve (16) is opened by the clamping action of the installed sealing rubber cylinder (22), and the sand flushing liquid returns to the sand flushing vehicle (10) through the lateral channel (20) of the reversing short circuit (7); after the reversing short circuit (7) passes through the wellhead sealing device (5), the sliding sleeve (16) of the reversing short section is reset under the action of the spring (15), and the sand flushing liquid returns to the sand flushing vehicle (10) through the bridge channel (19) of the reversing short circuit (7) and the faucet (8).

5. The horizontal well reverse circulation continuous sand flushing method according to claim 2, It is characterized in that The wellhead sealing device (5) has a height of 450 mm, and the sealing pressure of the sealing rubber cylinder (22) is 7 MPa.

6. The horizontal well reverse circulation continuous sand flushing method according to claim 3, It is characterized in that The maximum outer diameter of the cyclone sand flushing device (2) is 116 mm.

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