Combined type blanking plug and matched production process thereof

Abstract

The combined type blanking plug comprises a connecting short section and a functional short section, the lower end of the connecting short section is in threaded connection with the upper end of the functional short section, and the connecting short section is provided with a hollow channel for a continuous pipe to penetrate through. A slip for clamping the coiled tubing is arranged on the inner side wall of the connecting nipple; the functional short section is provided with a production channel, the lower end of the production channel of the functional short section is connected with a plug for plugging the lower end of the production channel in a sealed mode, and the plug is limited at the lower end of the production channel through a first limiting pin on the inner side wall of the production channel. According to the combined type blanking plug, the requirements of continuous pipe well completion, gas production and well repair integrated technology are met, and the requirements of continuous pipe lowering under pressure in the well completion stage, plug pumping-out production in the production stage, circulation channel building in the abnormal stage and well logging and sand washing operation in the well repair stage can be met.

Description

Technical Field

[0001] The invention relates to the technical field of continuous tubing well completion, and in particular to a composite plug and a matching production process thereof. Background Art

[0002] The coiled tubing completion plug is used in the downhole completion process. The coiled tubing is placed as the production string, and the plug is used as a downhole tool to plug the channel inside the coiled tubing, ensuring that the inner channel is not pressurized during the coiled tubing placement process, achieving the wellhead pressure operation condition. When the gas well needs to be put into production, the downhole plugging can be released through relevant processes to achieve full-bore production of the coiled tubing.

[0003] As production time goes by, blockages such as fracturing sand in the wellbore will gradually increase, resulting in obstruction of production flow and affecting production efficiency. The use of continuous tubing as the production string allows the production string to be directly used as the working string to carry out operating processes involving the inside of the pipe, requiring the production string to have a large inner diameter. At the same time, the downhole plug also needs to have a large flow rate to meet the requirements of large displacement and through-string operations.

[0004] At present, the patented technologies that have been disclosed are generally based on the design of casting and fishing plugging. After the production string is lowered, it is necessary to lower the steel wire or small-sized pipe string from the inside of the oil pipe to throttle or plug. The repeated lifting and lowering operation is cumbersome and has a single function. In view of the design of the existing plug, the utility model patent with the authorization number CN210530800U discloses a steel wire casting and fishing plug. The tool combines the locking mandrel, the balance valve and the one-way valve into a whole, realizing one-time operation. Only two trips of steel wire tools are needed to complete the plugging and removal, shortening the operation time. However, the design structure of the tool is complex, the matching is difficult, the function is limited, and it is only used for steel wire operation. The invention patent with the application number CN103510895A discloses a casting and fishing plug. The tool uses the slip mechanism and the sealing rubber to cooperate with the steel wire operation to achieve the sitting and plugging in the oil pipe, but the design function of the tool is single, and it can only be used for plugging and lacks the means of unsealing, and the scope of application is limited. The invention patent with application number CN113047804 A discloses a double-acting plugging device with a cast-in-place design. The tool adopts a truncated cone shape with a larger upper part and a smaller lower part at the lower end of the sealing outer ring platform, and a truncated cone shape with a smaller upper part and a larger lower part at the upper end of the sealing inner ring platform, so as to achieve bidirectional sealing and good sealing performance. The utility model with authorization number CN206376813 U discloses a preset oil pipe plugging device. The tool directly connects the working cylinder to the lower end of the oil pipe, and throws a plugging device into the working cylinder to seal the inner cavity of the working cylinder, thereby blocking the lower end of the oil pipe. After the oil pipe is lifted, there is no need to plug the oil pipe again.

[0005] In view of the need to realize the development of gas wells from completion to production, logging, sand flushing and other stages in the integrated process of continuous tubing completion and gas production and workover, there is currently a lack of pre-set downhole plugging operation tools that meet the needs of continuous tubing operations and have multiple functions such as pressure running, pump-out production, and large-diameter operations. Summary of the invention

[0006] In order to solve one or more technical problems existing in the prior art, the present invention provides a composite plug and a supporting production process thereof.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: a composite plug, comprising a connecting pup joint and a functional pup joint, the lower end of the connecting pup joint is threadedly connected to the upper end of the functional pup joint, the connecting pup joint has a hollow channel for the continuous pipe to pass through, and a slip for clamping the continuous pipe is provided on the inner side wall of the connecting pup joint; the functional pup joint has a production channel, and the lower end of the production channel of the functional pup joint is sealed and connected to a plug for blocking the lower end of the production channel, and the plug is limited at the lower end of the production channel by a first limit pin on the inner side wall of the production channel.

[0008] The beneficial effects of the present invention are as follows: the composite plug of the present invention can realize the requirements of the integrated process of continuous tubing completion, gas production and well repair, and can realize the requirements of running the continuous tubing under pressure in the completion stage, pumping out the plug for production in the production stage, establishing a circulation channel in the abnormal stage, and logging and sand flushing in the well repair stage. The composite plug of the present invention is easy to process, cost-controlled, without shrinkage, integrated in function, and reliable in supporting process. It can support and improve the integrated process system of continuous tubing completion, gas production and well repair, thereby simplifying the gas well development and completion process, and realizing safe and efficient construction operations.

[0009] Based on the above technical solution, the present invention can also be improved as follows.

[0010] Furthermore, the outer peripheral side wall of the plug is sealed and connected to the inner side wall of the production channel through a first sealing ring;

[0011] An annular step is provided on the outer peripheral side wall of the plug, and the annular step abuts against the lower end surface of the functional short section; the lower end of the plug is a conical structure.

[0012] The beneficial effects of adopting the above further solution are: the provision of the first sealing ring is conducive to the plug tightly sealing the production channel; the use of a plug with a conical structure facilitates the plug to fall from the wellbore.

[0013] Furthermore, a through hole connecting the production channel with the outside is opened on the side wall of the functional short section, and a sliding sleeve that blocks the through hole is also sealed in the production channel of the functional short section, and the sliding sleeve is limited in the production channel by a second limit pin on the inner wall of the production channel.

[0014] The beneficial effect of adopting the above further scheme is that the setting of the sliding sleeve and the second limit pin can be used as a backup plan for opening the production channel. When the lower end of the composite plug encounters obstruction or the plug is not dissolved, resulting in the plug being unable to be pumped out, the through hole on the side wall of the functional short section is opened by throwing a ball to establish circulation, which can effectively improve the construction success rate, reduce production costs, and ensure the smooth implementation of the completion and production operations.

[0015] Furthermore, a limiting protrusion for receiving the sliding sleeve is provided on the inner side wall of the production channel, and the limiting protrusion is located between the plug and the through hole, and the distance between the upper end surface of the limiting protrusion and the lower end edge of the through hole is not less than the axial length of the sliding sleeve.

[0016] The beneficial effect of adopting the above further solution is that the setting of the limiting protrusion prevents the sliding sleeve from escaping from the production channel.

[0017] Further, the second limit pin is located above the through hole; the portion of the sliding sleeve located above the through hole is sealed and connected to the inner wall of the production channel through a second sealing ring, and the portion of the sliding sleeve located below the through hole is sealed and connected to the inner wall of the production channel through a third sealing ring.

[0018] The beneficial effect of adopting the above further solution is that the sliding sleeve can effectively seal the production channel through the sealing ring.

[0019] Furthermore, the connecting short section includes an upper joint, a connecting short section shell and a lower joint, the upper end of the connecting short section shell is threadedly connected to the upper joint, the lower end of the connecting short section shell is threadedly connected to the lower joint, and the lower joint is threadedly connected to the upper end of the functional short section; the outer side wall of the upper end of the cava is limited on the inner side wall of the upper joint, and the part of the cava extending out of the upper joint is threadedly connected to the inner side wall of the connecting short section shell.

[0020] The beneficial effects of adopting the above further scheme are: the grab-type slips are used in conjunction with the continuous pipe, and there is no need to install additional special connectors for continuous pipes. The continuous pipes can be directly connected to the continuous pipes, and the degree of integration is high. Compared with conventional slips, the slips have the advantages of easy installation, anti-slip, large slip bite area, and prevention of continuous pipe shrinkage.

[0021] Furthermore, the inner side wall of the upper end of the connecting short section shell is threadedly connected to the outer side wall of the lower end of the upper joint, a limiting groove is formed on the inner side wall of the upper joint, and an annular limiting step is formed on the outer side wall of the upper end of the cava, and the limiting step is abutted against the lower end of the limiting groove through a fourth sealing ring.

[0022] Furthermore, the connecting short section also includes a rubber cylinder, the upper outer wall of the lower joint is threadedly connected to the lower inner wall of the connecting short section shell, the upper inner wall of the lower joint is provided with a first annular groove, the inner wall of the connecting short section shell is provided with a second annular groove, the second annular groove is located above the internal thread of the lower end of the connecting short section shell, and the rubber cylinder is clamped in the annular groove formed by the first annular groove and the second annular groove.

[0023] The beneficial effect of adopting the above further solution is that the setting of the rubber sleeve can achieve sealing cooperation with the continuous tube.

[0024] A composite plug supporting production process is implemented using the above-mentioned composite plug, comprising the following steps:

[0025] In the construction preparation stage, the tail end of the coiled tube is passed through the hollow passage of the connecting nipple and is clamped by the slip;

[0026] During the pressure-running stage, the coiled tubing is run into the wellbore as a production string to a preset depth, and the composite plug is placed at the tail end of the coiled tubing throughout the process to plug the internal channel of the coiled tubing;

[0027] During the gas test and production stage, the internal channel of the coiled tubing is pressurized by a pump truck. When the pressure difference between the internal channel of the coiled tubing and the wellbore reaches the pressure required for the first limit pin to cut off, the plug falls off, and a passage is formed between the internal channel of the coiled tubing and the wellbore, thus realizing gas test and production of the wellbore;

[0028] Or, in the gas test and production stage, the plug is made of soluble material, the coiled tubing is lowered into the wellbore to a preset depth and immersed in the liquid environment in the wellbore, the plug naturally dissolves in the liquid environment, and the internal channel of the coiled tubing forms a passage with the wellbore, thus realizing the wellbore gas test and production;

[0029] During the well repair operation stage, when the wellbore production is abnormal, it is necessary to carry out well condition monitoring or dredging, logging or sand flushing operations; when logging, the logging instrument is lowered along the continuous tubing, through the composite plugging device to the designated position for logging; when sand flushing, the surface pump group is connected to the continuous tubing, and the surface pump group is started for circulation operation, so that the plugging sand at the bottom of the well is returned from the wellhead along the annulus between the continuous tubing and the wellbore, realizing the continuous tubing sand flushing operation.

[0030] The beneficial effect of the present invention is that the supporting production process of the composite plug of the present invention adopts different functional combinations of designated process start-up tools through the steps to achieve development needs involving various stages of gas well production, including pipe plugging in the pressure-running stage, cyclic production in the gas trial production stage, and well logging and sand flushing construction in the well repair operation stage.

[0031] A composite plug supporting production process is implemented using the above-mentioned composite plug, comprising the following steps:

[0032] In the construction preparation stage, the tail end of the coiled tube is passed through the hollow passage of the connecting nipple and is clamped by the slip;

[0033] During the pressure-running stage, the coiled tubing is run into the wellbore as a production string to a preset depth, and the composite plug is placed at the tail end of the coiled tubing throughout the process to plug the internal channel of the coiled tubing;

[0034] During the gas test production stage, the internal channel of the coiled tubing is pressurized by using a pump truck. When the pressure difference between the internal channel of the coiled tubing and the wellbore fails to reach the pressure required for the first limit pin to cut, the plug cannot fall off; or when the pressure difference between the internal channel of the coiled tubing and the wellbore reaches the pressure required for the first limit pin to cut, but the lower end of the plug encounters resistance and the plug cannot fall off; at this time, a ball is thrown into the production channel of the functional short section by ground ball throwing to seal the upper end of the sliding sleeve, and the internal channel of the coiled tubing is continuously pressurized by the pump truck. The thrown ball is used to push the sliding sleeve downward to cut the second limit pin, so that the sliding sleeve opens the through hole on the side wall of the functional short section, so that the internal channel of the coiled tubing and the wellbore form a passage, realizing the wellbore gas test and production;

[0035] During the well repair operation stage, when the wellbore production is abnormal, it is necessary to carry out well condition monitoring or dredging, logging or sand flushing operations; when logging, the logging instrument is lowered along the continuous tubing, through the composite plugging device to the designated position for logging; when sand flushing, the surface pump group is connected to the continuous tubing, and the surface pump group is started for circulation operation, so that the plugging sand at the bottom of the well is returned from the wellhead along the annulus between the continuous tubing and the wellbore, realizing the continuous tubing sand flushing operation.

[0036] The beneficial effects of the present invention are as follows: the supporting production process of the composite plug of the present invention adopts different functional combinations of designated process start-up tools through the steps to achieve development needs involving various stages of gas well production, including pipe plugging during the pressure-running stage, circulating production during the gas trial production stage, ball pressure injection to establish lateral channels during abnormal operation conditions, and well logging and sand flushing construction during the well repair operation stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the cross-sectional structure of the connecting short section of the present invention;

[0038] Figure 2 for Figure 1 A schematic diagram of the enlarged structure of the middle part A;

[0039] Figure 3 It is a cross-sectional structural schematic diagram of the functional short section of the present invention;

[0040] Figure 4 It is a cross-sectional structural schematic diagram of the composite plug of the present invention;

[0041] Figure 5 It is a cross-sectional structural schematic diagram of the composite plugging device and the continuous tube of the present invention;

[0042] Figure 6 It is a schematic diagram of the structure of the coiled tubing with the composite plugging device of the present invention being lowered into the wellbore under pressure;

[0043] Figure 7 for Figure 6 A schematic diagram of the structure of the composite plug falling off;

[0044] Figure 8 For Figure 6 A schematic diagram of the structure of the middle composite plugger throwing ball;

[0045] Fig. 9 This is a schematic diagram of the structure of the well logging instrument of the present invention being lowered along the coiled tubing;

[0046] Fig.10 It is a structural schematic diagram of the sand flushing operation along the continuous pipe of the present invention.

[0047] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0048] 100, connecting nipple; 101, hollow channel; 102, slip; 103, upper joint; 104, connecting nipple shell; 105, lower joint; 106, limiting groove; 107, limiting step; 108, fourth sealing ring; 109, rubber cylinder; 110, fifth sealing ring; 111, sixth sealing ring; 112, anti-loosening screw;

[0049] 200, functional short section; 201, production channel; 202, through hole; 203, sliding sleeve; 204, second limiting pin; 205, limiting protrusion; 206, second sealing ring; 207, third sealing ring;

[0050] 300, plug; 301, first limit pin; 302, first sealing ring; 303, annular step; 304, conical structure;

[0051] 400, coiled tubing; 500, wellbore; 600, sphere; 700, logging instrument. DETAILED DESCRIPTION

[0052] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0053] like Figures 1 to 10As shown, a composite plug of the present embodiment comprises a connecting nipple 100 and a functional nipple 200, wherein the lower end of the connecting nipple 100 is threadedly connected to the upper end of the functional nipple 200, the connecting nipple 100 has a hollow channel 101 for the continuous tube 400 to pass through, and a slip 102 for clamping the continuous tube 400 is provided on the inner side wall of the connecting nipple 100; the functional nipple 200 has a production channel 201, and the lower end of the production channel 201 of the functional nipple 200 is sealedly connected to a plug 300 for blocking the lower end of the production channel 201, and the plug 300 is limited at the lower end of the production channel 201 by a first limiting pin 301 on the inner side wall of the production channel 201.

[0054] like Figure 3 As shown, the outer peripheral side wall of the plug 300 of this embodiment is sealed and connected to the inner side wall of the production channel 201 through the first sealing ring 302; an annular step 303 is provided on the outer peripheral side wall of the plug 300, and the annular step 303 abuts against the lower end surface of the functional short section 200; the lower end of the plug 300 is a conical structure 304. The provision of the first sealing ring is conducive to the plug tightly sealing the production channel; the plug with a conical structure is convenient for the plug to fall from the wellbore.

[0055] like Figure 3 As shown, a through hole 202 for connecting the production channel 201 with the outside is provided on the side wall of the functional sub 200 of this embodiment, and a sliding sleeve 203 for blocking the through hole 202 is also sealedly connected in the production channel 201 of the functional sub 200, and the sliding sleeve 203 is limited in the production channel 201 by a second limiting pin 204 on the inner wall of the production channel 201. The setting of the sliding sleeve and the second limiting pin can be used as a backup plan for opening the production channel. When the plug cannot be pumped out due to the obstruction at the lower end of the composite plug or the plug is not dissolved, the through hole on the side wall of the functional sub is opened by throwing a ball to establish a circulation, which can effectively improve the construction success rate, reduce production costs, and ensure the smooth implementation of the completion and production operation.

[0056] like Figure 3 As shown, the inner side wall of the production channel 201 of this embodiment is further provided with a limiting protrusion 205 for receiving the sliding sleeve 203, the limiting protrusion 205 is located between the plug 300 and the through hole 202, and the distance between the upper end surface of the limiting protrusion 205 and the lower end edge of the through hole 202 is not less than the axial length of the sliding sleeve 203. The setting of the limiting protrusion prevents the sliding sleeve from falling out of the production channel.

[0057] like Figure 3As shown, the second stop pin 204 of this embodiment is located above the through hole 202; the portion of the sliding sleeve 203 located above the through hole 202 is sealed and connected to the inner wall of the production channel 201 through a second sealing ring 206, and the portion of the sliding sleeve 203 located below the through hole 202 is sealed and connected to the inner wall of the production channel 201 through a third sealing ring 207. The sliding sleeve can effectively seal the production channel through the sealing ring.

[0058] like Figure 1 and Figure 2 As shown, the connecting nipple 100 of this embodiment includes an upper joint 103, a connecting nipple shell 104 and a lower joint 105. The upper end of the connecting nipple shell 104 is threadedly connected to the upper joint 103, the lower end of the connecting nipple shell 104 is threadedly connected to the lower joint 105, and the lower joint 105 is threadedly connected to the upper end of the functional nipple 200; the outer wall of the upper end of the slip 102 is limited on the inner wall of the upper joint 103, and the part of the slip 102 extending from the upper joint 103 is threadedly connected to the inner wall of the connecting nipple shell 104. The grab-type slip is used to cooperate with the coiled tubing, and there is no need to install a special connector for the coiled tubing. It can be directly connected to the coiled tubing, with a high degree of integration. Compared with conventional slips, it has the advantages of easy installation, anti-dropping, large slip bite area, and preventing the coiled tubing from shrinking.

[0059] Specifically, Figure 1 As shown, a fifth sealing ring 110 is provided on the inner side wall of the hollow channel 101 of the upper joint 103 of the connecting nipple 100, and the hollow channel 101 of the connecting nipple 100 can be sealed and connected to the continuous pipe 400 through the fifth sealing ring 110. A sixth sealing ring 111 is provided on the inner side wall of the hollow channel 101 of the lower joint 105 of the connecting nipple 100, and the hollow channel 101 of the connecting nipple 100 can also be sealed and connected to the continuous pipe 400 through the sixth sealing ring 111. The lower end of the connecting nipple shell 104 is threadedly connected to the upper end external thread of the lower joint 105 through an internal thread. The lower end of the connecting nipple shell 104 is also provided with a locking screw 112, which penetrates the lower end outer wall of the connecting nipple shell 104 and abuts against the upper end outer wall of the lower joint 105. Preferably, a step can be provided on the upper end outer wall of the lower joint 105, and the locking screw 112 can abut against the lower side of the step.

[0060] Among them, the slips 102 of this embodiment adopt grab-type slips, and the outer edge of the slips 102 has an external thread structure, which matches the inner wall thread of the connecting short section shell 104. The inner wall thread of the connecting short section shell 104 presents a tapered structure that is narrow at the top and wide at the bottom. When installing the continuous pipe 400 into the slips 102, the continuous pipe 400 is first fully inserted into the slips, and then the upper joint 103 and the connecting short section shell 104 are slightly loosened. The upper joint 103 drives the slip teeth (external thread structure) of the slips 102 to move toward the upper edge of the continuous pipe 400. Due to the tapered structure of the inner wall thread of the connecting short section shell 104, the slips gradually shrink along the tapered structure, so that the slip teeth are engaged with the outer wall surface of the continuous pipe 400, thereby realizing the mutual connection between the connecting short section 100 and the continuous pipe 400. That is, the slips are pressed by the upper joint and the outer shell thread of the connecting nipple, so that the slip teeth are engaged with the outer wall of the coiled tubing, and the connection between the connecting nipple and the coiled tubing is realized. The tighter the thread is compacted, the tighter the slips are engaged with the coiled tubing. The slips adopt grab-type slips, which have a larger connection area and a small shrinkage degree of anchoring the coiled tubing.

[0061] like Figure 1 and Figure 2 As shown, the inner side wall of the upper end of the connecting short section housing 104 of this embodiment is threadedly connected to the outer side wall of the lower end of the upper joint 103, a limiting groove 106 is formed on the inner side wall of the upper joint 103, and an annular limiting step 107 is formed on the outer side wall of the upper end of the cava 102, and the limiting step 107 abuts against the lower end of the limiting groove 106 through a fourth sealing ring 108.

[0062] like Figure 1 As shown, the connecting nipple 100 of this embodiment further includes a rubber sleeve 109, the upper end outer wall of the lower joint 105 is threadedly connected to the lower end inner wall of the connecting nipple shell 104, a first annular groove is provided on the upper end inner wall of the lower joint 105, a second annular groove is provided on the inner wall of the connecting nipple shell 104, the second annular groove is located above the inner thread of the lower end of the connecting nipple shell 104, and the rubber sleeve 109 is clamped in the annular groove formed by the first annular groove and the second annular groove. The setting of the rubber sleeve can achieve sealing cooperation with the continuous pipe, and one or more rubber sleeves can be provided. The rubber sleeve is compressed and fits the outer wall of the continuous pipe by pressing the connecting nipple shell and the lower joint thread, so as to achieve sealing between the oil pipe and the tool.

[0063] Among them, Figure 1 to Figure 3 As shown, the various components of the composite plug of this embodiment have equal diameters and no reduction in diameter, which is consistent with the outer diameter of the connected coiled pipe. Preferably, the diameter of each component of the composite plug needs to be greater than 2-3 / 8in to meet the needs of large-diameter coiled pipe installation and large-diameter flow.

[0064] The composite plug of this embodiment is designed to meet the needs of the integrated process of coiled tubing completion, gas production and well repair, and can realize the requirements of running the coiled tubing under pressure in the completion stage, pumping out the plug for production in the production stage, establishing a circulation channel in the abnormal stage, and logging and sand flushing in the well repair stage. The composite plug of this embodiment is easy to process, cost-controlled, has no shrinkage, integrated functions, and reliable supporting processes. It can support and improve the integrated process system of coiled tubing completion, gas production and well repair, thereby simplifying the gas well development and completion process and achieving safe and efficient construction operations.

[0065] like Figure 6 , Figure 7 , Fig. 9 and Fig.10 As shown, a composite plug supporting production process of this embodiment is implemented by using the above-mentioned composite plug, and includes the following steps:

[0066] In the construction preparation stage, the tail end of the coiled tube 400 is passed through the hollow channel 101 of the connecting nipple 100 and clamped by the slip 102;

[0067] During the pressure-running stage, the coiled tubing 400 is run into the wellbore 500 as a production string to a preset depth, and the composite plugging device is placed at the tail end of the coiled tubing 400 to block the internal channel of the coiled tubing 400;

[0068] During the gas test production stage, the internal channel of the coiled tubing 400 is pressurized by a pump truck, so that the pressure difference between the internal channel of the coiled tubing 400 and the wellbore 500 reaches the pressure required for the first limit pin 301 to cut off, and the plug 300 falls off, so that the internal channel of the coiled tubing 400 and the wellbore 500 form a passage, and the wellbore 500 is put into gas test and put into production;

[0069] Or, in the gas test production stage, the plug 300 is made of soluble material, the coiled tubing 400 is lowered into the wellbore 500 to a preset depth and immersed in the liquid environment in the wellbore 500, the plug 300 naturally dissolves in the liquid environment, and the internal channel of the coiled tubing 400 forms a passage with the wellbore 500 to achieve gas test and production of the wellbore 500; wherein, the plug 300 can adopt the existing soluble oil pipe plug that can be used for downhole oil operations, such as degradable resin, soluble magnesium alloy, soluble aluminum alloy, etc. (for example, the patent with publication number CN 115874119A and the name of the invention is soluble aluminum alloy for downhole choke parts and its preparation method and application; the patent with publication number CN208934650U and the name of the invention is a removable soluble oil well pipe plug, etc.).

[0070] During the well repair operation, when the production of the wellbore 500 is abnormal, it is necessary to carry out well condition monitoring or dredging, and perform logging or sand flushing operations; when logging, the logging instrument 700 is lowered along the coiled tubing 400, passed through the composite plugging device to the designated position for logging; when sand flushing, the surface pump group is connected to the coiled tubing 400, and the surface pump group is started for circulation operation, so that the plugging sand at the bottom of the well is returned from the wellhead along the annulus between the coiled tubing 400 and the wellbore 500, thereby realizing the sand flushing operation of the coiled tubing 400.

[0071] The supporting production process of the composite plug of this embodiment adopts different functional combinations of designated process start-up tools through the steps to achieve development needs involving various stages of gas well production, including pipe lowering and plugging in the pressure-running stage, circulating production in the gas trial production stage, and logging and sand flushing construction in the well repair operation stage.

[0072] like Figure 8 to Figure 10 As shown, a composite plug supporting production process of this embodiment is implemented by using the above-mentioned composite plug, and includes the following steps:

[0073] In the construction preparation stage, the tail end of the coiled tube 400 is passed through the hollow channel 101 of the connecting nipple 100 and clamped by the slip 102;

[0074] During the pressure-running stage, the coiled tubing 400 is run into the wellbore 500 as a production string to a preset depth, and the composite plugging device is placed at the tail end of the coiled tubing 400 to block the internal channel of the coiled tubing 400;

[0075] During the gas test production stage, the internal channel of the coiled tubing 400 is pressurized by using a pump truck. When the pressure difference between the internal channel of the coiled tubing 400 and the wellbore 500 fails to reach the pressure required for the shearing of the first limit pin 301, the plug 300 cannot fall off; or when the pressure difference between the internal channel of the coiled tubing 400 and the wellbore 500 reaches the pressure required for the shearing of the first limit pin 301, but the lower end of the plug 300 encounters resistance, the plug 300 cannot fall off; at this time, a ball 600 is thrown into the production channel of the functional short section 200 by ground ball throwing, the upper end of the sliding sleeve 203 is blocked, and the internal channel of the coiled tubing 400 is continuously pressurized by the pump truck, and the thrown ball 600 is used to push the sliding sleeve 203 to move downward, the second limit pin 204 is cut off, so that the sliding sleeve 203 opens the through hole 202 on the side wall of the functional short section 200, so that the internal channel of the coiled tubing 400 and the wellbore 500 form a passage, and the wellbore 500 is tested for gas and put into production;

[0076] During the well repair operation, when the production of the wellbore 500 is abnormal, it is necessary to carry out well condition monitoring or dredging, and perform logging or sand flushing operations; when logging, the logging instrument 700 is lowered along the coiled tubing 400, passed through the composite plugging device to the designated position for logging; when sand flushing, the surface pump group is connected to the coiled tubing 400, and the surface pump group is started for circulation operation, so that the plugging sand at the bottom of the well is returned from the wellhead along the annulus between the coiled tubing 400 and the wellbore 500, thereby realizing the sand flushing operation of the coiled tubing 400.

[0077] The supporting production process of the composite plug of this embodiment adopts different functional combinations of designated process start-up tools through the steps to achieve development needs involving various stages of gas well production, including pipe plugging during the pressure-running stage, circulation production during the gas trial production stage, ball pressure injection to establish lateral channels during abnormal operation conditions, and logging and sand flushing construction during the well repair operation stage.

[0078] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0079] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0080] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0082] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0083] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A composite plug, characterized in that: It comprises a connecting nipple and a functional nipple, wherein the lower end of the connecting nipple is threadedly connected with the upper end of the functional nipple, the connecting nipple has a hollow passage for the continuous pipe to pass through, and a slip for clamping the continuous pipe is arranged on the inner side wall of the connecting nipple; the functional nipple has a production channel, and the lower end of the production channel of the functional nipple is sealedly connected with a plug for blocking the lower end of the production channel, and the plug is limited at the lower end of the production channel by a first limit pin on the inner side wall of the production channel.

2. A composite plug according to claim 1, characterized in that: The outer peripheral side wall of the plug is sealed and connected to the inner side wall of the production channel through a first sealing ring; An annular step is provided on the outer peripheral side wall of the plug, and the annular step abuts against the lower end surface of the functional short section; the lower end of the plug is a conical structure.

3. A composite plug according to claim 1 or 2, characterized in that: A through hole connecting the production channel with the outside is opened on the side wall of the functional short section, and a sliding sleeve that blocks the through hole is also sealed in the production channel of the functional short section. The sliding sleeve is limited in the production channel by a second limit pin on the inner wall of the production channel.

4. A composite plug according to claim 3, characterized in that: A limiting protrusion for receiving the sliding sleeve is also provided on the inner side wall of the production channel, and the limiting protrusion is located between the plug and the through hole, and the distance between the upper end surface of the limiting protrusion and the lower end edge of the through hole is not less than the axial length of the sliding sleeve.

5. A composite plug according to claim 3, characterized in that: The second limit pin is located above the through hole; the part of the sliding sleeve located above the through hole is sealed and connected to the inner wall of the production channel through a second sealing ring, and the part of the sliding sleeve located below the through hole is sealed and connected to the inner wall of the production channel through a third sealing ring.

6. A composite plug according to claim 1, characterized in that: The connecting short section includes an upper joint, a connecting short section shell and a lower joint, the upper end of the connecting short section shell is threadedly connected to the upper joint, the lower end of the connecting short section shell is threadedly connected to the lower joint, and the lower joint is threadedly connected to the upper end of the functional short section; the outer side wall of the upper end of the cava is limited on the inner side wall of the upper joint, and the part of the cava extending out of the upper joint is threadedly connected to the inner side wall of the connecting short section shell.

7. A composite plug according to claim 6, characterized in that: The inner side wall of the upper end of the connecting short section shell is threadedly connected to the outer side wall of the lower end of the upper joint, a limiting groove is formed on the inner side wall of the upper joint, and an annular limiting step is formed on the outer side wall of the upper end of the cava, and the limiting step abuts against the lower end of the limiting groove through a fourth sealing ring.

8. A composite plug according to claim 6, characterized in that: The connecting short section also includes a rubber cylinder, the upper outer wall of the lower joint is threadedly connected to the lower inner wall of the connecting short section shell, the upper inner wall of the lower joint is provided with a first annular groove, the inner wall of the connecting short section shell is provided with a second annular groove, the second annular groove is located above the internal thread of the lower end of the connecting short section shell, and the rubber cylinder is clamped in the annular groove formed by the first annular groove and the second annular groove.

9. A composite plugging device supporting production process, characterized in that: The composite plugging device according to any one of claims 1 to 8 is used, comprising the following steps: In the construction preparation stage, the tail end of the coiled tube is passed through the hollow passage of the connecting nipple and is clamped by the slip; During the pressure-running stage, the coiled tubing is run into the wellbore as a production string to a preset depth, and the composite plug is placed at the tail end of the coiled tubing throughout the process to plug the internal channel of the coiled tubing; During the gas test and production stage, the internal channel of the coiled tubing is pressurized by a pump truck. When the pressure difference between the internal channel of the coiled tubing and the wellbore reaches the pressure required for the first limit pin to cut off, the plug falls off, and a passage is formed between the internal channel of the coiled tubing and the wellbore, thus realizing gas test and production of the wellbore; Or, in the gas test and production stage, the plug is made of soluble material, the coiled tubing is lowered into the wellbore to a preset depth and immersed in the liquid environment in the wellbore, the plug naturally dissolves in the liquid environment, and the internal channel of the coiled tubing forms a passage with the wellbore, thus realizing the wellbore gas test and production; During the well repair operation stage, when the wellbore production is abnormal, it is necessary to carry out well condition monitoring or dredging, logging or sand flushing operations; when logging, the logging instrument is lowered along the continuous tubing, through the composite plugging device to the designated position for logging; when sand flushing, the surface pump group is connected to the continuous tubing, and the surface pump group is started for circulation operation, so that the plugging sand at the bottom of the well is returned from the wellhead along the annulus between the continuous tubing and the wellbore, realizing the continuous tubing sand flushing operation.

10. A composite plugging device supporting production process, characterized in that: The composite plugging device according to any one of claims 3 to 5 is used, comprising the following steps: In the construction preparation stage, the tail end of the coiled tube is passed through the hollow passage of the connecting nipple and is clamped by the slip; During the pressure-running stage, the coiled tubing is run into the wellbore as a production string to a preset depth, and the composite plug is placed at the tail end of the coiled tubing throughout the process to plug the internal channel of the coiled tubing; During the gas test production stage, the internal channel of the coiled tubing is pressurized by using a pump truck. When the pressure difference between the internal channel of the coiled tubing and the wellbore fails to reach the pressure required for the first limit pin to cut, the plug cannot fall off; or when the pressure difference between the internal channel of the coiled tubing and the wellbore reaches the pressure required for the first limit pin to cut, but the lower end of the plug encounters resistance and the plug cannot fall off; at this time, a ball is thrown into the production channel of the functional short section by ground ball throwing to seal the upper end of the sliding sleeve, and the internal channel of the coiled tubing is continuously pressurized by the pump truck. The thrown ball is used to push the sliding sleeve downward to cut the second limit pin, so that the sliding sleeve opens the through hole on the side wall of the functional short section, so that the internal channel of the coiled tubing and the wellbore form a passage, realizing the wellbore gas test and production; During the well repair operation stage, when the wellbore production is abnormal, it is necessary to carry out well condition monitoring or dredging, logging or sand flushing operations; when logging, the logging instrument is lowered along the continuous tubing, through the composite plugging device to the designated position for logging; when sand flushing, the surface pump group is connected to the continuous tubing, and the surface pump group is started for circulation operation, so that the plugging sand at the bottom of the well is returned from the wellhead along the annulus between the continuous tubing and the wellbore, realizing the continuous tubing sand flushing operation.

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