Loss control completion string and method

Abstract

The present invention relates to a well completion string and method for controlling leakage. The method for controlling leakage comprises the following steps: lowering a setting string part into the well, so that the setting string part is set and hung on an outer casing, the setting string part comprising a leakage control component; in a first state, the leakage control component is opened by lowering a back-inserted string part into the well and engaging a leakage control switch tool in the back-inserted string part with the leakage control component, so that the upper and lower parts of the setting string part are connected; in a second state, the leakage control component is closed by lifting the back-inserted string part, so that the upper and lower parts of the setting string part are isolated.

Description

Technical Field

[0001] The present invention relates to the technical field of well completion in petroleum engineering, and in particular to a well completion string for controlling lost circulation. The present invention also relates to a method for controlling lost circulation. Background Art

[0002] With the in-depth exploitation of oil and gas resources. The current oil and gas exploitation work has begun to focus on formations and oil wells with complex well conditions and fragile wells. In this case, during the drilling, cementing, completion, testing, exploitation and well repair of oil and gas exploitation, the well site may have the problem of leakage of working fluid (including drilling fluid, cement slurry, completion fluid, etc.), that is, it directly enters the formation under the action of pressure difference, thereby causing the loss of working fluid and affecting the normal progress of downhole operations. This will seriously affect the smooth progress of downhole operations and ultimately cause large production losses. Common types of working fluid leakage mainly include permeability leakage, fracture leakage and cave leakage. In the prior art, when the working fluid leaks, chemical plugging agents or cement are generally used to plug the wellbore. If not handled properly, it may cause other complex situations and even cause the wellbore to be scrapped.

[0003] CN204960820U discloses a multifunctional oil testing completion string for wells prone to blowout and leakage. The string combines the plugging function into the completion string to facilitate plugging operations during the completion process. However, the plugging function of this string is one-time. If the leakage problem recurs in the well, it is necessary to replace the string through a complex process or solve it through other existing complex plugging methods. Summary of the invention

[0004] In view of the above problems, the present invention proposes a leakage control completion string and method, by which unlimited leakage plugging operations can be achieved.

[0005] According to a first aspect of the present invention, a loss control method is proposed, comprising the following steps: lowering a sealing tubing string portion into the well, so that the sealing tubing string portion is seated and hung on an outer casing, the sealing tubing string portion comprising a loss control component; in a first state, the loss control component is opened by lowering a return tubing string portion into the well and engaging a loss control switch tool in the return tubing string portion with the loss control component, so that the upper and lower parts of the sealing tubing string portion are connected; in a second state, the loss control component is closed by lifting the return tubing string portion, so that the upper and lower parts of the sealing tubing string portion are isolated.

[0006] Through the above method, it is possible to switch between the first state and the second state an unlimited number of times according to the action relationship between the setting pipe string part and the reinsertion pipe string part. In the first state, normal downhole operations can be carried out. In the second state, effective plugging can be carried out. Therefore, plugging can be achieved according to the actual needs of the downhole through simple operations.

[0007] In one embodiment, in the second state, the lost circulation control assembly is closed by lifting the reinserted tubing string portion and separating the lost circulation control switch tool from the lost circulation control assembly, so that the upper and lower parts of the set tubing string are isolated.

[0008] In one embodiment, in the first state, the loss control assembly is opened by a pressing action of the loss control switch tool.

[0009] In one embodiment, during the completion, production and / or workover process, the normal operation and the loss control operation are repeatedly switched by repeatedly switching between the first state and the second state. Thus, the reinserted tubing string can be replaced without killing the well, or the well can be temporarily controlled to prevent loss.

[0010] According to the second aspect of the present invention, a sealing tubular column section is proposed. The sealing tubular column section can be used in the above-mentioned loss control method. The sealing tubular column section includes a loss control component, and the loss control component is used to cooperate with the loss control switch tool in the reinserted tubular column section, wherein the loss control component is opened by pressing down the reinserted tubular column section and engaging the loss control switch tool with the loss control component, allowing the upper and lower parts of the sealing tubular column section to be connected; the loss control component is closed by lifting the reinserted tubular column section, so that the upper and lower parts of the sealing tubular column section are isolated.

[0011] In one embodiment, the leakage control assembly includes: a lower cylindrical shell; an upper support sleeve sleeved in the lower cylindrical shell, the lower end of the upper support sleeve is provided with a hinged bracket extending longitudinally downward, and a flow channel extending longitudinally is formed in the upper support sleeve; a spherical valve core, the spherical valve core is arranged under the upper support sleeve and is hingedly connected to the hinged bracket, the spherical valve core is constructed with a flow hole penetrating the spherical valve core in one direction; and an offset drive rod, the offset drive rod is sleeved between the upper support sleeve and the lower cylindrical shell, and is extended along The biased drive rod extends in the longitudinal direction, and the lower end of the biased drive rod is hinged to the spherical valve core at a position deviated from the hinged bracket; wherein, in the second state, the flow hole of the spherical valve core extends in the transverse direction, and the spherical valve core is blocked at the lower end of the flow channel of the upper support sleeve, so that the flow hole is not connected with the flow channel; in the first state, the biased drive rod is driven by the leakage control switch tool to move downward to drive the spherical valve core to rotate downward, so that the flow hole extends in the longitudinal direction and the flow hole is connected with the flow channel.

[0012] In one embodiment, the leakage control assembly also includes: a lower support sleeve, which is sleeved in the lower cylindrical outer shell and is below the spherical valve core; and a first elastic member sleeved between the lower support sleeve and the lower cylindrical outer shell, the upper end and the lower end of the first elastic member respectively abut against the lower support sleeve and the lower cylindrical outer shell to achieve compression; wherein, the lower support sleeve is sealed with the lower cylindrical outer shell, and the lower support sleeve is sealed with the spherical valve core.

[0013] In one embodiment, the loss control assembly also includes: an upper cylindrical shell connected to the lower cylindrical shell; a transmission sleeve sleeved in the upper cylindrical shell, the transmission sleeve being connected to the upper end of the bias drive rod; and a second elastic member in a compressed state sleeved between the upper cylindrical shell and the transmission sleeve, the upper end of the second elastic member abutting against the upper step surface of the transmission sleeve facing downward, and the lower end of the second elastic member abutting against the upper step surface of the upper cylindrical shell facing upward; in a first state, the transmission sleeve is engaged with the loss control switch tool, and the loss control switch tool pushes the transmission sleeve downward, and thereby pushes the bias drive rod downward, so that the second elastic member is further compressed; in a second state, the second elastic member releases its elastic potential energy, driving the transmission sleeve and the bias drive rod to move upward.

[0014] According to the third aspect of the present invention, a reinserted tubular column section is proposed. The reinserted tubular column section can be used in the above-mentioned loss control method. The reinserted tubular column section includes a loss control switch tool, which is used to cooperate with the loss control component in the sealing tubular column section, wherein the loss control component is opened by pressing down the reinserted tubular column section and engaging the loss control switch tool with the loss control component, allowing the upper and lower parts of the sealing tubular column section to be connected; the loss control component is closed by lifting the reinserted tubular column section, so that the upper and lower parts of the sealing tubular column section are isolated.

[0015] In one embodiment, the loss control switch tool comprises a longitudinally extending switch cylinder, a joint piece is provided on the outer side wall of the switch cylinder, and the sealing joint piece is configured to cooperate with the inner wall of the transmission sleeve configured in the loss control assembly.

[0016] In one embodiment, the leakage control switch tool also includes a longitudinally extending flushing cylinder connected below the switch cylinder. When the sealing engagement member on the switch cylinder cooperates with the transmission sleeve, the flushing cylinder is inserted into the leakage control component for flushing the leakage control component.

[0017] According to a fourth aspect of the present invention, a lost circulation control completion string is provided. The lost circulation control completion string comprises the above-mentioned setting string portion and the above-mentioned reinsertion string portion.

[0018] In one embodiment, the lost circulation control completion string is used to perform the lost circulation control method described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be described in more detail below with reference to the accompanying drawings, wherein:

[0020] Figure 1 The structure of the lost circulation control completion string according to the present invention is schematically shown;

[0021] Figure 2 Schematically shows Figure 1 The structure of the reinserted tubing string portion in the lost circulation control completion tubing string shown;

[0022] Figure 3 Schematically shows Figure 1 The structure of the setting string part in the lost circulation control completion string is shown;

[0023] Figure 4 Shows Figure 3 A portion of the structure of the valve body mechanism in the setting string portion shown;

[0024] Figure 5 Another part of the valve body structure in the setting pipe section is shown.

[0025] In the drawings, the same reference numerals are used for the same components. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] In the present application, it should be noted that the end of the lost circulation control completion string lowered into the wellbore close to the wellhead is defined as the upper end or similar terms, and the end away from the wellhead is defined as the lower end or similar terms.

[0028] Figure 1 The structure of the lost circulation control completion string 100 according to the present invention is shown, and the lost circulation control completion string 100 includes a return string portion 1 and a setting string portion 2 that fit together. The return string portion 1 can be inserted and installed inside the setting string portion 2, thereby forming an adaptive connection with the setting string portion 2. The return string portion 1 can be used to connect with an oil pipe (not shown). Figure 2 and Figure 3 Schematic structures of the reinsertion tubing string part 1 and the sealing tubing string part 2 are shown respectively.

[0029] like Figure 2 As shown, the reinserted tubing string part 1 includes a release tool 11, a sealing nipple 12, a load indicator 14 and a loss control switch tool 16 which are arranged in sequence from top to bottom. A first length matching nipple 13 can be arranged between the sealing nipple 12 and the load indicator 14 to adjust the distance between the sealing nipple 12 and the load indicator 14 according to the downhole conditions. Similarly, a second length matching nipple 15 is arranged between the load indicator 14 and the loss control switch tool 16 to adjust the distance between the load indicator 14 and the loss control switch tool 16 according to the downhole conditions. In addition, in a preferred embodiment, the reinserted tubing string part 1 may also include a flushing cylinder 17 connected below the loss control switch tool 16.

[0030] like Figure 3 As shown, the sealing string part 2 includes a reinsertion anchoring tool 21, a packer 22, a positioning clamp 25 and a loss control assembly arranged in sequence from top to bottom. The loss control assembly generally includes a driving mechanism 23 and a valve body mechanism 24 connected below the driving mechanism 23. In addition, the sealing string part 2 may also include other pipe string structures (not shown) connected below the loss control assembly, which may include other conventional structures of the tail pipe used in the cementing completion process.

[0031] The release tool 11 in the reinserted pipe string section 1 is used to engage with the reinserted anchoring tool 21 in the setting pipe string section 2, so as to be used in the reinserted pipe string section 1. Figure 1When the sealing column 2 is inserted into the sealing column 2, the two are connected in an adaptive manner. The release tool 11 here can be a mechanical release tool with a claw, or other forms of release tools. In addition,

[0032] The sealing nipple 12 in the reinserted tubular string section 1 can be used to achieve sealing cooperation with the outer setting tubular string section 2. Thus, it is possible to prevent fluid from flowing through the annulus between the reinserted tubular string section 1 and the setting tubular string section 2.

[0033] The sealing string part 2 can be used to achieve sealing with the outer casing to seal the annulus between the outer casing and the sealing string part 2. This can prevent the fluid from flowing from the annulus to the bottom of the well, especially the leakage point at the bottom of the well. In addition, this can also prevent the underground high pressure from being transmitted to the wellhead and causing a blowout.

[0034] The load indicator 14 in the reinserted tubular string section 1 can be used to cooperate with the positioning clamp 25 in the setting tubular string section 2. The load indicator 14 can be configured as a protrusion. When the reinserted tubular string section 1 is inserted into the setting tubular string section 2, as shown in FIG. Figure 1 As shown, the load indicator 14 abuts against the positioning clamp 25. At this time, the pressure of the return pipe string part 1 will increase sharply. The operator can use this as a basis to determine that the return pipe string part 1 has been inserted into the sealing pipe string part 2 and stop the subsequent running operation.

[0035] The leakage control tool 16 in the reinserted pipe string portion 1 may include a switch barrel extending longitudinally, and a coupling member 161 ( Figure 2 ). Accordingly, if Figure 3 As shown, the driving mechanism 23 of the leakage control assembly in the sealing pipe column part 2 includes an upper cylindrical shell 231, a transmission sleeve 233 sleeved in the upper cylindrical shell, and a second elastic member 232 sleeved between the upper cylindrical shell 231 and the transmission sleeve 233. The upper end of the second elastic member 232 abuts against the upper step surface of the transmission sleeve 233 facing downward, and the lower end of the second elastic member 232 abuts against the upper step surface of the upper cylindrical shell 231 facing upward. As a result, the second elastic member 232 is in a compressed state. The second elastic member 232 can be a coil spring, a disc spring, or any other suitable second elastic member. An engagement groove 233A for engaging with the above-mentioned engagement member 161 is provided on the inner wall of the transmission sleeve 233. Through the engagement between the engagement groove 233A and the engagement member 161, the leakage control tool 16 can drive the transmission sleeve 233 to move downward together during the process of inserting the pipe column part 1 downward. Preferably, the engaging member 161 and the engaging groove 233A are both constructed in an annular shape.

[0036] In a preferred embodiment, the engagement groove 233A is configured near the bottom end of the transmission sleeve 233 .

[0037] It should be understood that the above-mentioned engagement groove 233A may also be replaced by an engagement step or any other appropriate structure provided on the inner wall of the transmission sleeve 233, as long as the above-mentioned function can be achieved.

[0038] The valve body mechanism 24 in the setting string part 2 can be used to selectively open or close under the driving action of the driving mechanism 23, thereby achieving upper and lower communication or upper and lower isolation in the setting string part. Figure 4 The specific structure of an embodiment of the valve body mechanism 24 is specifically shown. In order to show the internal structure and working mechanism of the valve body mechanism 24 in detail, Figure 4 The lower cylindrical housing 241 is omitted.

[0039] The valve body mechanism 24 includes a lower cylindrical housing 241 ( Figure 3 ), and an upper support sleeve 242 sleeved in the lower cylindrical shell 241. The upper support sleeve 242 is formed in a cylindrical shape, and a flow channel extending longitudinally is formed inside it. A hinge bracket 243 extending longitudinally downward is provided at the lower end of the upper support sleeve 242. The hinge bracket 243 is preferably as Figure 4 As shown, it is formed into two rods that are relatively spaced apart. The valve body mechanism 24 also includes a spherical valve core 244 arranged below the upper support sleeve 242, and a flow hole 245 is constructed on the spherical valve core 244 that penetrates the spherical valve core 244 in one direction. The spherical valve core 244 is hingedly matched with the above-mentioned hinged bracket 243, so that the spherical valve core 244 can rotate around the hinged position. The valve body mechanism 24 can also include an offset drive rod 246 extending generally in the longitudinal direction. The offset drive rod 246 is sleeved outside the upper support sleeve. The lower end of the offset drive rod 246 is hinged to the spherical valve core 244, and the upper end is fixedly connected to the transmission sleeve 233 mentioned above. Figure 4 In the preferred embodiment shown, a through hole 242A is configured on the side wall of the upper support sleeve 242 and radially penetrates the side wall. On the one hand, the transmission sleeve 233 extends longitudinally downward to a position overlapping with the through hole 242A. On the other hand, the upper end of the biasing driving rod 246 extends longitudinally upward to a position overlapping with the through hole 242A, and radially extends inward to be fixedly connected with the transmission sleeve 233. In this way, the fixed connection and transmission function between the biasing driving rod 246 and the transmission sleeve 233 are achieved.

[0040] When the valve body mechanism 24 is closed (i.e., the second state), the flow hole 245 of the spherical valve core 244 is oriented in the transverse direction. As a result, the flow channel in the upper support sleeve 242 cannot be connected to other pipe string structures below through the flow hole 245 of the spherical valve core 244. At this time, the upper and lower isolation in the setting pipe string part 2 is achieved.

[0041] In the state where the valve body mechanism 24 is open (i.e., the first state), as Figure 1 As shown, the bias drive rod 246 is driven by the downward movement of the transmission sleeve 233, and then provides a downward force to the spherical valve core 244. Since the force deviates from the position where the spherical valve core 244 is connected to the hinge bracket 243, the spherical valve core 244 will rotate downward under the action of the force until the flow hole 245 of the spherical valve core 244 is rotated to a position oriented in the longitudinal direction. This allows the flow channel in the upper support sleeve 242 to be connected to other pipe string structures below through the flow hole 245 of the spherical valve core 244. At this time, the upper and lower connections in the setting pipe string part 2 are achieved.

[0042] like Figure 5 As shown, the valve body mechanism 24 may also include a lower support sleeve 247 disposed under the spherical valve core 244. The lower support sleeve 247 is sleeved in the lower cylindrical shell 241 and is sealed by a sealing ring 249 disposed therebetween. The valve body mechanism 24 also includes a first elastic member 248 sleeved between the lower support sleeve 247 and the lower cylindrical shell 241. The upper end of the first elastic member 248 abuts against the step surface 247A of the lower support sleeve 247 facing downward, and the lower end abuts against the step surface 241A of the lower cylindrical shell 241 facing upward, and is thus in a compressed state. Therefore, the lower support sleeve 247 can be pressed against the surface of the spherical valve core 244 above under the action of the first elastic member 248. The lower support sleeve 247 can also be designed so that the area of ​​the effective pressure-bearing surface facing downward is larger than that of the effective pressure-bearing surface facing upward, so that the lower support sleeve 247 can also be pressed against the surface of the spherical valve core 244 upward under the action of the pressure in the pipe string. Figure 5 The first state in which the valve body mechanism 24 is opened is shown. At this time, the flow hole 245 of the spherical valve core 244 is connected to the space in the lower support sleeve 247, and thus is connected to other pipe string structures below, so as to achieve the upper and lower communication in the setting string part 2. In the second state, the flow hole 245 of the spherical valve core 244 is oriented horizontally, and thus is not connected to the space in the lower support sleeve 247. At this time, under the effect of the sealing cooperation between the spherical valve core 244 and the lower support sleeve 247 and the sealing cooperation between the lower support sleeve 247 and the lower cylindrical shell 241, the upper and lower isolation in the setting string part 2 can be conveniently and effectively ensured.

[0043] In addition, the flushing cylinder 17 connected under the leakage control switch tool 16 can extend downward to the position in the upper support sleeve 242 close to the spherical valve core 244. The flushing cylinder 17 can be used to flush the valve body mechanism 24 to better clean the impurities accumulated on the spherical valve core 244, thereby avoiding the problem of clogging, jamming, etc. of the valve body mechanism 24 that hinders the smooth operation of the valve body mechanism 24.

[0044] The following will describe in detail the various structures in the reinsertion string part 1 and the setting string part 2 and the related matching methods and technical effects in combination with the working process of the lost circulation control method.

[0045] When a loss occurs in the well during drilling, or when a cementing and completion operation is performed in a wellbore prone to loss, the setting string portion 2 in the loss control completion string 100 can be sent into the wellbore by a running tool. During the running-in process, since the driving mechanism 23 is not driven by a downward force, the valve body mechanism 24 of the loss control assembly is in a closed state (second state). Therefore, during the running-in process, serious loss in the well can be avoided to a certain extent.

[0046] When the sealing string part 2 is lowered to the predetermined position, the setting and sealing between the sealing string part 2 and the outer sleeve is achieved by reinserting the anchoring tool 21 and the packer 22 .

[0047] Afterwards, a series of leakage control operations can be performed as needed.

[0048] If it is determined that no leakage or obvious leakage occurs in the current state, the reinserted tubular column part 1 can be lowered. During the lowering process, the leakage control switch tool 16 in the reinserted tubular column part 1 is engaged with the drive mechanism 23 of the leakage control assembly in the setting tubular column part 2. As a result, the reinserted tubular column part 1 can drive the transmission sleeve 233 in the drive mechanism 23 to move downward together. As it moves downward, the valve body mechanism 24 is driven by the drive mechanism 23 and switches from the above-mentioned closed state (second state) to the open state (first state). In this process, the second elastic member 232 in the drive mechanism 23 is further compressed to accumulate elastic potential energy.

[0049] When the reinserted tubular string part 1 is lowered until the load indicator 14 cooperates with the positioning clamp 25 and issues a pressure increase indication, it can be determined that the reinserted tubular string part 1 is inserted into the setting tubular string part 2. The hand release tool 11 in the reinserted tubular string part 1 and the reinserted anchoring tool in the setting tubular string part 2 can be connected and matched, and the sealing nipple 12 can be used to achieve the sealing match between the reinserted tubular string part 1 and the setting tubular string part 2.

[0050] When the reinsertion string portion 1 is inserted into the setting string portion 2 so that the valve body mechanism 24 is in an open state, normal downhole operations can be performed, including well completion, production and well repair.

[0051] If leakage is found again in the well, the connection between the return pipe string part 1 and the sealing pipe string part 2 can be disconnected by pulling up the return pipe string part 1. Continuing to pull up the return pipe string part 1, the pressure transmission cylinder 233 in the drive mechanism 23 is no longer subjected to the downward pressure, and the drive mechanism 23 is separated from the leakage control opening tool 16. The second elastic member 232 in the switch mechanism 23 can release the elastic potential energy and reset upward, thereby driving the transmission sleeve 233 and the biasing drive rod 246 to move upward. This causes the spherical valve core 244 to rotate upward to the closed state (second state) of the lower end of the upper support sleeve 242. As a result, the interior of the sealing pipe string part 1 is sealed up and down, thereby preventing the working fluid in the wellbore above the sealing pipe string part 2 from leaking.

[0052] In the whole process of downhole operation from drilling to production, once leakage occurs, the above method can be used to control the leakage. In addition, by lifting and lowering the inserting string part 1, it is possible to achieve repeated switching between the first state and the second state without killing the well. Thus, it is possible to freely switch between normal operation and leakage control operation, or between normal operation and replacement of the inserting string part 1.

[0053] This enables the control and completion string 100 to quickly close the valve body mechanism 24 in the event of a loss, thereby significantly reducing the amount of working fluid lost when a loss occurs during completion. This effectively avoids the huge operating costs and operating risks in the operation process of wells prone to loss, is conducive to improving the operating efficiency and enhancing the operating effect of completion operations and subsequent oil and gas production operations, and is of great significance to completion operations and subsequent oil and gas production operations.

[0054] In the present invention, unless otherwise specified or contradictory, the terms "longitudinal", "lateral", "upper", "lower", etc. are all described relative to the extension direction of the wellbore. The term "upper" refers to the side close to the wellbore along the extension direction of the wellbore. The term "lower" refers to the side close to the bottom of the well along the extension direction of the wellbore.

[0055] In the present invention, it should be noted that the terms "first" and "second" are used for descriptive purposes only and cannot 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 one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0056] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" 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 representation of the above terms does 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.

[0057] Finally, it should be noted that the above is only a preferred embodiment of the present invention and does not constitute any limitation to the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for a person skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for controlling leakage, comprising the following steps: The sealing string part is lowered into the well, and the sealing string part is set and hung on the outer casing. The sealing string part includes a loss control component; the loss control component includes a valve body mechanism. During the lowering process, the valve body mechanism is in a closed state. In the first state, the valve body mechanism of the loss control assembly is opened by inserting the reinserted tubing string into the well and engaging the loss control switch tool in the reinserted tubing string with the loss control assembly, so that the upper and lower parts of the setting tubing string are connected; In the second state, the reinserted tubular string portion is lifted up to disconnect the reinserted tubular string portion from the setting tubular string portion, so as to close the valve body mechanism of the leakage control assembly, thereby isolating the setting tubular string portion from top to bottom; The leakage control assembly comprises: a lower cylindrical shell; an upper support sleeve sleeved in the lower cylindrical shell, the lower end of the upper support sleeve is provided with a hinge bracket extending longitudinally downward, and a flow channel extending longitudinally is formed in the upper support sleeve; a spherical valve core, the spherical valve core is arranged under the upper support sleeve and is hingedly connected to the hinge bracket, the spherical valve core is constructed with a flow hole penetrating the spherical valve core in one direction; and an offset drive rod, the offset drive rod is sleeved between the upper support sleeve and the lower cylindrical shell, and is longitudinally extended to the upper support sleeve. The bias drive rod extends in a direction, and the lower end of the bias drive rod is hinged with the spherical valve core at a position deviated from the hinge bracket; wherein, in the second state, the flow hole of the spherical valve core extends in the transverse direction, and the spherical valve core is blocked at the lower end of the flow channel of the upper support sleeve, so that the flow hole is not connected with the flow channel; in the first state, the bias drive rod is driven by the leakage control switch tool to move downward to drive the spherical valve core to rotate downward, so that the flow hole extends in the longitudinal direction, and the flow hole is connected with the flow channel; The loss control assembly also includes: an upper cylindrical shell connected to the lower cylindrical shell; a transmission sleeve sleeved in the upper cylindrical shell, the transmission sleeve being connected to the upper end of the bias drive rod; and a second elastic member in a compressed state sleeved between the upper cylindrical shell and the transmission sleeve, the upper end of the second elastic member abutting against the upper step surface of the transmission sleeve facing downward, and the lower end of the second elastic member abutting against the upper step surface of the upper cylindrical shell facing upward; in a first state, the transmission sleeve is engaged with the loss control switch tool, and the loss control switch tool pushes the transmission sleeve downward, and thereby pushes the bias drive rod downward, so that the second elastic member is further compressed; in a second state, the second elastic member releases its elastic potential energy, driving the transmission sleeve and the bias drive rod to move upward.

2. The method for controlling leakage according to claim 1, characterized in that: In the second state, the loss control assembly is closed by lifting the reinserted tubing string portion and separating the loss control switch tool from the loss control assembly, so that the upper and lower parts of the setting tubing string are isolated.

3. The method for controlling leakage according to claim 1, characterized in that: In the first state, the loss control assembly is opened by a downward pressing action of the loss control switch tool.

4. The method for controlling leakage according to any one of claims 1 to 3, characterized in that: During the well completion, production and / or well repair process, the normal operation and the loss control operation are repeatedly switched by repeatedly switching between the first state and the second state.

5. A sealing tubing string section used in the loss control method according to any one of claims 1 to 4, the sealing tubing string section comprising a loss control assembly, the loss control assembly being used to cooperate with a loss control switch tool in the reinserted tubing string section, the loss control assembly comprising a valve body mechanism, and during the running process, the valve body mechanism is in a closed state, wherein: The loss control assembly is opened by pressing down the reinserted tubing string portion and engaging the loss control switch tool with the loss control assembly, allowing the upper and lower parts of the sealing tubing string portion to be connected; the loss control assembly is closed by lifting up the reinserted tubing string portion to disconnect the connection between the reinserted tubing string portion and the sealing tubing string portion, so that the upper and lower parts of the sealing tubing string portion are sealed off.

6. The setting string section according to claim 5, characterized in that: The leakage control component also includes: A lower support sleeve, which is sleeved in the lower cylindrical shell and is located below the spherical valve core; and A first elastic member sleeved between the lower support sleeve and the lower cylindrical outer shell, wherein the upper end and the lower end of the first elastic member respectively abut against the lower support sleeve and the lower cylindrical outer shell to achieve compression; Wherein, the lower support sleeve is sealed with the lower cylindrical shell, and the lower support sleeve is sealed with the spherical valve core.

7. A reinserted tubing string section used in a lost circulation control method according to any one of claims 1 to 4, the reinserted tubing string section comprising a lost circulation control switch tool for cooperating with a lost circulation control component in a set tubing string section, the lost circulation control component comprising a valve body mechanism, and during the running-in process, the valve body mechanism is in a closed state, wherein: The loss control assembly is opened by pressing down the reinserted tubing string portion and engaging the loss control switch tool with the loss control assembly, allowing the upper and lower parts of the sealing tubing string portion to be connected; the loss control assembly is closed by lifting up the reinserted tubing string portion to disconnect the connection between the reinserted tubing string portion and the sealing tubing string portion, so that the upper and lower parts of the sealing tubing string portion are sealed off.

8. The reinserted pipe column portion according to claim 7, characterized in that: The leakage control switch tool comprises a switch cylinder extending longitudinally, and a coupling piece is arranged on the outer side wall of the switch cylinder. The coupling piece is configured to cooperate with the inner wall of a transmission sleeve configured in the leakage control assembly.

9. The lost circulation control completion string according to claim 7, characterized in that: The leakage control switch tool also includes a longitudinally extending flushing cylinder connected below the switch cylinder. When the sealing engagement member on the switch cylinder cooperates with the transmission sleeve, the flushing cylinder is inserted into the leakage control component for flushing the leakage control component.

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