A device for multiple switching coiled tubing

Abstract

The application discloses a device for multiple switch coiled tubing, one end of a first inner connector is sleeved in the coiled tubing, one end of a second inner connector is sleeved in the other end of the first inner connector, the other end of the second inner connector is inserted into one end of a protective cover, the other end of the protective cover is sleeved on a guide head; a sliding sleeve is arranged in the first inner connector, a retreat-stop expansion block is arranged on the sliding sleeve, a leaf spring is arranged on the retreat-stop expansion block, a check valve seat is arranged in the first inner connector, a check ball valve is arranged on the upper end of the second inner connector, wherein the check ball valve is connected with the second inner connector through a pin shaft, and a spring is sleeved on the pin shaft; a plug seat is arranged on the lower end of the second inner connector, wherein a sealing gasket and a plug are arranged on the lower end of the plug seat, the device can reduce the safety risk generated by only relying on the pipe opening sealing during the coiled tubing pressure pipe lifting operation, and improve the reliability of the coiled tubing pressure sealing.

Description

Technical Field

[0001] This invention belongs to the field of tight gas field development technology and relates to a device for repeatedly switching continuous tubing. Background Technology

[0002] Tight gas wells, exemplified by the Changqing Sulige Gas Field, have short high-pressure periods and long low-pressure periods. 75% of the cumulative gas production is generated during the low-pressure period. Using coiled tubing as the velocity string for drainage and gas production has become one of the three main drainage and gas production technologies in the Sulige Gas Field, and has been applied in over 1000 wells with good results. However, as the energy of the gas well decreases, when the actual production of the gas well falls below the critical fluid-carrying flow rate of the coiled tubing in use, fluid accumulation occurs again in the well. This necessitates pulling out the coiled tubing from the wellbore and then implementing other drainage and gas production processes such as foam drainage and plunger lift. To address this situation, the current coiled tubing live-line pulling process in the gas field mainly uses a single-stage plugging process at the tubing end. This plugging distance is short, with the plug only inserted to a depth of 1 meter into the tubing. The plugging process is complex, time-consuming, and carries high risks. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a device for repeatedly opening and closing coiled tubing. This device can reduce the safety risks caused by relying solely on pipe end sealing during live tubing lifting operations and improve the reliability of live tubing sealing.

[0004] To achieve the above objectives, the device for multiple switching of a continuous tubing according to the present invention includes a continuous tubing, a first inner tube, a second inner tube, a protective cover, and a guide head;

[0005] One end of the first inner tube is fitted into the continuous tubing, one end of the second inner tube is fitted into the other end of the first inner tube, the other end of the second inner tube is inserted into one end of the protective cover, and the other end of the protective cover is fitted into the guide head.

[0006] The first inner tube is provided with a sliding expansion sleeve, the sliding expansion sleeve is provided with a backstop expansion block, the backstop expansion block is provided with a leaf spring, the first inner tube is provided with a check valve seat, and the upper end of the second inner tube is provided with a check ball valve. The check ball valve and the second inner tube are connected by a pin, and a spring is sleeved on the pin.

[0007] The lower end of the second inner pipe is provided with a plug seat, wherein the lower end of the plug seat is provided with a sealing gasket and a plug.

[0008] The continuous tubing is connected to the first inner tube by a roll-fit connection.

[0009] A first sealing ring is provided between the coiled tubing and the first inner tube.

[0010] A second sealing ring is provided between the first inner tube and the sliding sleeve.

[0011] A third sealing ring is provided between the check valve seat and the first inner pipe.

[0012] The first inner tube and the second inner tube are fixed together by a first screw, and a fourth sealing ring is provided between the first inner tube and the second inner tube.

[0013] The plug seat and the second inner pipe are connected by shear pins.

[0014] An outer sealing ring is provided between the plug seat and the second inner pipe, and an inner sealing ring is provided on the inner side of the plug seat.

[0015] A sleeve is fitted onto the outside of the plug.

[0016] The guide head is connected to the first inner tube by a second screw.

[0017] The present invention has the following beneficial effects:

[0018] In specific operation, the coiled tubing switching device of the present invention involves pre-installing a coiled tubing switching tool at the tail end of the coiled tubing on the surface. During the insertion of the coiled tubing into the well, the coiled tubing switching tool is in a closed state to prevent natural gas and fluid from being produced along the coiled tubing in the wellbore. When the coiled tubing is used as a production string for velocity string drainage and gas production, the coiled tubing switching tool is in an open state, allowing natural gas and fluid from the wellbore to be produced along the coiled tubing to the wellhead, ensuring gas production using velocity string drainage and gas production. When it is necessary to pull out the coiled tubing, the coiled tubing switching tool is in a closed state to seal the tail end of the coiled tubing, again preventing natural gas and fluid from being produced along the coiled tubing in the wellbore. This ensures the safety of pulling out the coiled tubing under pressure, reduces the safety risks caused by relying solely on pipe end sealing during live tubing pull-out operations, and improves the reliability of live tubing sealing. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention;

[0020] Figure 2 A schematic diagram of the structure of the present invention after removing the plug 22;

[0021] Figure 3 This is a schematic diagram of the structure of the invention when the pitch is not under pressure;

[0022] Figure 4 This is a schematic diagram of the structure of the present invention when the ball is pressurized and then depressurized, and the ball disc and valve seat form a seal.

[0023] Among them, 1 is the continuous tubing, 2 is the first sealing ring, 3 is the first inner pipe, 4 is the sliding sleeve, 5 is the second sealing ring, 6 is the stop expansion block, 7 is the leaf spring, 8 is the stop valve seat, 9 is the third sealing ring, 10 is the stop ball flap, 11 is the pin, 12 is the spring, 13 is the fourth sealing ring, 14 is the second inner pipe, 15 is the first screw, 16 is the protective cover, 17 is the plug seat, 18 is the outer sealing ring, 19 is the inner sealing ring, 20 is the shear pin, 21 is the sealing gasket, 22 is the plug, 23 is the sleeve, 24 is the second screw, 25 is the guide head, and 26 is the ball. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0025] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0026] refer to Figures 1 to 4 The device for multiple switching of continuous tubing according to the present invention includes continuous tubing 1, first inner tube 3, second inner tube 14, protective cover 16 and guide head 25;

[0027] One end of the first inner tube 3 is fitted into the continuous tubing 1, one end of the second inner tube 14 is fitted into the other end of the first inner tube 3, the other end of the second inner tube 14 is inserted into one end of the protective cover 16, and the other end of the protective cover 16 is fitted onto the guide head 25.

[0028] Among them, the continuous tubing 1 and the first inner tube 3 are connected by a rolling connection, and a first sealing ring 2 is provided between the continuous tubing 1 and the first inner tube 3.

[0029] The first inner tube 3 is provided with a sliding sleeve 4, and a second sealing ring 5 is provided between the first inner tube 3 and the sliding sleeve 4.

[0030] The sliding sleeve 4 is equipped with a backstop block 6, and the backstop block 6 is equipped with a leaf spring 7;

[0031] The first inner pipe 3 is provided with a check valve seat 8, and a third sealing ring 9 is provided between the check valve seat 8 and the first inner pipe 3;

[0032] The first inner tube 3 and the second inner tube 14 are fixed together by the first screw 15, and a fourth sealing ring 13 is provided between the first inner tube 3 and the second inner tube 14.

[0033] The upper end of the second inner tube 14 is provided with a check valve 10, and the check valve 10 is connected to the second inner tube 14 by a pin 11, on which a spring 12 is sleeved.

[0034] The lower end of the second inner tube 14 is provided with a plug seat 17, wherein the plug seat 17 is connected to the second inner tube 14 by a shear pin 20, and an outer sealing ring 18 is provided between the plug seat 17 and the second inner tube 14, and an inner sealing ring 19 is provided on the inner side of the plug seat 17.

[0035] The lower end of the plug seat 17 is provided with a sealing gasket 21 and a plug 22. A sleeve 23 is fitted onto the outside of the plug 22 to protect it from corrosion. The function of the plug 22 is to prevent fluid from being produced from the wellbore during the operation of the coiled tubing 1.

[0036] The guide head 25 is connected to the first inner tube 3 by the second screw 24. The guide head 25 plays a guiding role, making it less likely to encounter obstruction when the coiled tubing 1 is run into the well.

[0037] The specific working process of this invention is as follows:

[0038] 1) On the ground, a coiled tubing switch tool is pre-installed at the bottom of coiled tubing 1 and then lowered into the wellbore to the designed depth along with coiled tubing 1.

[0039] 2) Open the coiled tubing switch tool and use coiled tubing 1 for drainage and gas production.

[0040] Nitrogen gas is introduced into the coiled tubing 1 and pressurized. The plug 22 is removed into the cavity. The gas well uses the coiled tubing 1 as the velocity string for drainage and gas production.

[0041] 3) Throwing and applying pressure

[0042] When the gas well cannot carry the fluid normally using the coiled tubing 1, a ball 26 is inserted into the coiled tubing 1 at the surface. Nitrogen gas is then injected into the coiled tubing 1 and pressurized. The pressure difference generated by the ball 26 pushes it downward, causing the sliding sleeve 4 to move to the check valve seat 8. After further pressurization, the high-pressure gas pushes the ball 26 to move the sliding sleeve 4, check valve seat 8, and check ball disc 10 to continue sliding. The spring 12 is compressed, and the check valve seat 8 and check ball disc 10 come into contact until the leaf spring 7 on the anti-reverse expansion block 6 enters the groove and springs open.

[0043] 4) Depressurize and close the coiled tubing switch tool again.

[0044] After depressurization, the pressure difference generated above and below the ball 26 pushes the ball 26 upward to the anti-reverse expansion block 6 and then back to the top of the slide groove. Due to the limited position, the anti-reverse expansion block 6 cannot slide upward. At this time, the anti-reverse expansion block 6 cannot slide, and the natural gas at the bottom of the wellbore and the spring 12 push the check ball valve 10 to create a seal between the check valve seat 8 and the coiled tubing switch tool is closed again.

Claims

1. A device for repeatedly switching on and off a continuous oil tubing, characterized in that, It includes a coiled tubing (1), a first inner tube (3), a second inner tube (14), a protective cover (16), and a guide head (25); One end of the first inner tube (3) is fitted into the continuous tubing (1), one end of the second inner tube (14) is fitted into the other end of the first inner tube (3), the other end of the second inner tube (14) is inserted into one end of the protective cover (16), and the other end of the protective cover (16) is fitted onto the guide head (25). The first inner tube (3) is provided with a sliding sleeve (4), the sliding sleeve (4) is provided with a backstop block (6), the backstop block (6) is provided with a leaf spring (7), the first inner tube (3) is provided with a check valve seat (8), the upper end of the second inner tube (14) is provided with a check ball valve (10), wherein the check ball valve (10) and the second inner tube (14) are connected by a pin (11), and a spring (12) is sleeved on the pin (11); The lower end of the second inner pipe (14) is provided with a plug seat (17), wherein the lower end of the plug seat (17) is provided with a sealing gasket (21) and a plug (22).

2. The apparatus for repeatedly switching continuous tubing according to claim 1, characterized in that, The continuous tubing (1) and the first inner tube (3) are connected by a rolling connection.

3. The apparatus for repeatedly switching continuous tubing according to claim 1, characterized in that, A first sealing ring (2) is provided between the coiled tubing (1) and the first inner tube (3).

4. The apparatus for repeatedly switching continuous tubing according to claim 3, characterized in that, A second sealing ring (5) is provided between the first inner tube (3) and the sliding sleeve (4).

5. The apparatus for repeatedly switching continuous tubing according to claim 4, characterized in that, A third sealing ring (9) is provided between the check valve seat (8) and the first inner pipe (3).

6. The apparatus for repeatedly switching continuous tubing according to claim 5, characterized in that, The first inner tube (3) and the second inner tube (14) are fixed together by a first screw (15), and a fourth sealing ring (13) is provided between the first inner tube (3) and the second inner tube (14).

7. The apparatus for repeatedly switching continuous tubing according to claim 1, characterized in that, in, The plug seat (17) is connected to the second inner pipe (14) by a shear pin (20).

8. The apparatus for repeatedly switching continuous tubing according to claim 7, characterized in that, An outer sealing ring (18) is provided between the plug seat (17) and the second inner pipe (14), and an inner sealing ring (19) is provided on the inner side of the plug seat (17).

9. The apparatus for repeatedly switching continuous tubing according to claim 1, characterized in that, A sleeve (23) is fitted onto the outside of the plug (22).

10. The apparatus for repeatedly switching continuous tubing according to claim 6, characterized in that, The guide head (25) is connected to the first inner tube (3) by a second screw (24).

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