A system and method for handling complex problems in horizontal well sections

Abstract

The present invention discloses a system and method for dealing with complex problems in horizontal well sections, which solves the problems of safely, reliably and quickly dealing with sticking accidents and lost circulation accidents in horizontal well sections. The present invention includes a wellhead circulation device, a downhole while-drilling treatment device and a horizontal well fishing device. The downhole while-drilling treatment device includes a piston, a plugging sub and a back-off sub. The plugging sub and the back-off sub are detachably coaxially connected. A side through hole is formed in the side wall of the plugging sub near the upper end. The piston is coaxially arranged in the plugging sub. The outer wall of the upper end of the piston is connected to the inner wall of the plugging sub through an elastic member. A limiting device is arranged on the shaft section of the piston near the lower end. The limiting device is detachably connected to the back-off sub. The horizontal well fishing device is used for fishing the plugging ball. The wellhead circulation device has a high-pressure supply port, and the high-pressure supply port is used for connecting with the well pipe to provide forward driving force for the plugging ball. The present invention has the advantages of being able to safely, reliably and quickly deal with downhole sticking accidents, lost circulation accidents, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of oil production, and particularly to a system and method for dealing with complex problems in a horizontal well section. Background Art

[0002] Sticking and lost circulation in the horizontal well section are the most serious and complex accidents in the drilling engineering, and also the most difficult downhole accidents to handle. They affect safe drilling, endanger the equipment and personal safety, and will cause a large waste of time, cost and other resources. If effective solutions cannot be taken as soon as possible, a series of chain reactions will occur, and even the wellhead will be scrapped eventually.

[0003] Sticking usually occurs at places where the outer diameter of the drill string is larger, such as the positions of the drill bit, centralizer and drill collar. If measures such as acid soaking and shock cannot release it, only the method of back-off and over-milling can be used to deal with it. However, back-off is also a relatively complex procedure. Before back-off, the drill string is first tightened, and then based on the weight of the drill string above the sticking point, the buoyancy and friction of the mud, accurate calculations are carried out to determine the weight of the drill string that needs to be lifted, so as to back off the drill string at the required position. These complex procedures take a lot of time to complete, and will also delay the best time for accident handling, leading to the further deterioration of the accident. At present, most accidents adopt the method of explosive release in the later stage, but explosive release also has greater risks and safety hazards, and the cost is also very expensive, up to more than 200,000 yuan for each explosion.

[0004] Therefore, there is an urgent need for a system that can comprehensively handle sticking, lost circulation and fishing for downhole tools in the horizontal well section. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to safely, reliably and quickly handle sticking and lost circulation accidents in the horizontal well section, and the purpose is to provide a system and method for dealing with complex problems in the horizontal well section.

[0006] The present invention is achieved by the following technical solutions:

[0007] A system for handling complex problems in a horizontal well section, comprising a wellhead circulation device, a downhole while-drilling treatment device, and a horizontal well fishing device. The downhole while-drilling treatment device includes a piston, a plugging sub with an axial through-hole, and a back-off sub with an axial through-hole. The lower end of the plugging sub is detachably and coaxially connected to the upper end of the back-off sub. A side through-hole is formed on the side wall of the plugging sub near the upper end. The piston is coaxially arranged in the through-hole of the plugging sub. The outer wall of the upper end of the piston is connected to the inner wall of the plugging sub through an elastic member. The elastic member can provide an elastic force to the piston so that the piston has a tendency to slide relative to the plugging sub. The lower end of the piston is located in the through-hole of the back-off sub. A limiting device is arranged on the shaft section of the piston near the lower end. The limiting device is detachably connected to the back-off sub to limit the rotation of the back-off sub. The horizontal well fishing device is used to fish for a plugging ball. The horizontal well fishing device has an elastic buckle for cooperating with the fishing spear of the plugging ball. The wellhead circulation device has a high-pressure supply port, which is used to connect to a well pipe to provide forward driving force for the plugging ball. A sealing component for sealing a cable is also arranged in the wellhead circulation device. In the working state of bypass plugging, the plugging ball is pushed by the pressure provided by the wellhead circulation device to move the piston downward so that the upper end face of the piston is below the side through-hole, and the side through-hole is in an open state to inject a plugging fluid. In the working state of back-off, the plugging ball is pushed by the pressure provided by the wellhead circulation device to move the piston downward so that the limiting device of the piston is separated from the back-off sub, and the back-off sub is in a rotatable state so that the back-off sub can be separated from the plugging sub. In the working state of fishing for the plugging ball, the horizontal well fishing device cooperates with the plugging ball through the pressure provided by the wellhead circulation device to achieve the fishing of the plugging ball.

[0008] The present invention systematically integrates a wellhead circulation device, a downhole while-drilling processing device, and a horizontal well fishing device to effectively and safely handle complex downhole accidents, especially for well loss and stuck pipe situations occurring in the horizontal well section. The downhole while-drilling processing device is connected to the downhole drill string, so that installation is avoided when a downhole accident occurs, saving the time for accident handling. When well loss occurs, a plugging ball is manually dropped from the wellhead circulation device. At this time, pressure is applied to the well through a high-pressure generating source. Under the action of the plugging ball pressure, it advances along the extension direction of the well. When the plugging ball contacts the piston, the piston is pushed downward by the plugging ball until the top surface of the piston is below the side through-hole. At this time, the side through-hole connects the inside of the plugging nipple with the annulus outside the plugging nipple, and a plugging fluid is injected into the well to achieve the effect of downhole plugging. When a stuck pipe occurs, on the basis of the operation of pushing the piston downward for plugging, pressure is continuously applied to the well to further push the plugging ball downward until the limiting device of the piston is separated from the back-off sub. At this time, the drill string can be rotated in the reverse direction to achieve the back-off effect. When fishing for the plugging ball, the cable can be sealed through the sealing assembly of the wellhead circulation device, so that the high-pressure generating function and the cable sealing function are integrated, reducing the use of redundant sealing structures and improving the processing efficiency of complex downhole problems.

[0009] In the present invention, the horizontal well fishing device needs to cooperate with the fishing spear on the plugging ball to fish for the plugging ball, which belongs to the prior art, and those skilled in the art can implement it reasonably according to the prior art materials.

[0010] As a specific implementation manner, the through-hole of the plugging nipple is a stepped hole, the inner diameter of the upper end of the plugging nipple is larger than that of the lower end, the radial cross-section of the piston is T-shaped, the diameter of the upper end of the piston is larger than that of the lower end, one end of the elastic member is connected to the lower end surface of the large-diameter section of the piston, and the other end is connected to the lower end surface of the large inner diameter of the plugging nipple. Through the structural settings of the plugging nipple and the piston, the gap reservation between the piston and the plugging nipple is avoided, so that overall, the sizes of the piston or the plugging nipple are small, which is beneficial to the lifting of the plugging nipple. In this embodiment, the elastic member can be a spring evenly distributed along the circumference of the piston, a hydraulic rod evenly distributed along the circumference of the piston, or a spring piece evenly distributed along the circumference of the piston. The circumferentially even distribution method is to make the direction of the force on the piston along the axial direction of the piston.

[0011] Furthermore, the elastic member is a spring, and the elastic member is sleeved on the small-diameter section of the piston. When the elastic member is a spring sleeved on the piston, the number of elastic members is one at this time, so as to save costs, and at the same time, using a spring makes the assembly process simpler.

[0012] Further, a blocking ring is threadedly engaged with the upper end of the through hole of the plugging nipple. The blocking ring contacts the upper end of the piston to axially limit the piston. After the blocking ring is threadedly engaged with the plugging nipple, the position of the blocking ring relative to the plugging nipple can be adjusted, so that the contact areas between the two ends of the spring and the piston and the plugging nipple are increased, and the elastic force direction provided by the spring is closer to the axial direction of the piston.

[0013] Preferably, the opening at the upper end of the piston is provided in a conical shape, and the diameter of the upper end of the cone is larger than the diameter of the lower end of the cone. During plugging and back-off, this opening needs to be blocked by a blocking ball. After being set in a conical shape, the blocking surface of the blocking ball is correspondingly set in a conical shape. Then, during the blocking process, the conical opening forms a limit for the blocking ball in its circumferential direction, preventing the blocking ball from being skewed and causing the blocking to fail.

[0014] Preferably, the wellhead circulation device includes a three-way pipe body, a sealing assembly, and a sealing cover. The diameter of the port a of the three-way pipe body is enlarged to form a sealing cylinder. The port b of the three-way pipe body serves as a high-pressure supply port, and port b is coaxial with port a. The port c of the three-way pipe body is used to connect to a high-pressure generating source. The sealing assembly is disposed in the sealing cylinder. The sealing cover has a threaded connection end adapted to the outer wall of port a. The sealing cover is sleeved on the outer wall of port a and is threadedly engaged. The sealing assembly is pressed into the sealing cylinder through the sealing cover. The sealing assembly is used to seal the cable of the horizontal well fishing device. After the horizontal well fishing device enters the well, the sealing cover is closed, and the well pressure is provided by the high-pressure generating source to make the horizontal well fishing device move forward. The setting of the sealing assembly prevents the occurrence of pressure relief.

[0015] Further, the sealing assembly includes a rubber core, a core support, and an extrusion block. The core support, the rubber core, and the extrusion block are sequentially arranged coaxially in the sealing cylinder. The rubber core includes a first rubber core and a second rubber core. The first rubber core has a first contact plane, and a first cable groove penetrating axially along the sealing cylinder is opened on the first contact plane. Along the axial direction of the sealing cylinder, the first cable groove has several enlarged diameter segments. The second rubber core has a second contact plane, and a second cable groove penetrating axially along the sealing cylinder is opened on the second contact plane. Along the axial direction of the sealing cylinder, the second cable groove has several enlarged diameter segments. When the first contact plane is attached to the second contact plane, the enlarged diameter segments of the first cable groove correspond to the enlarged diameter segments of the second cable groove one by one. The extrusion block is located between the rubber core and the sealing cover. A structure for clamping the cable is formed inside the rubber core, improving the sealing effect on the cable.

[0016] Further, the end of the rubber core close to the sealing cover is provided in a conical shape, and the extrusion block has a conical concave surface adapted to the conical shape. The extrusion block serves as a pressure transmission component. Through the conical setting, the cable is uniformly stressed at the port of the rubber core, preventing the cable from being excessively bent and preventing serious wear between the cable and the port of the rubber core during sliding.

[0017] A method for dealing with complex problems in a horizontal well section, applying the above-mentioned system for dealing with complex problems in a horizontal well section, includes the following steps: S1, assemble the wellhead circulation device, connect the wellhead to the wellhead circulation device and configure a high-pressure generating source for the wellhead circulation device; S2, put a plug ball into the well through the wellhead circulation device; S3, start the high-pressure generating source to provide well pressure in the well so that the plug ball contacts the piston; S4, according to the type of downhole problems, provide well pressure through the wellhead circulation device to build up pressure in the well so that the plug ball pushes the piston downward; S5, close the high-pressure generating source, put a horizontal well fishing device through the wellhead circulation device, stop moving forward when the horizontal well fishing device reaches a well inclination of 57°-60°, seal the cable of the horizontal well fishing device through the sealing assembly, start the high-pressure generating source, and control the displacement at 4-6 L / S to push the horizontal well fishing device forward in the horizontal well section; S6, when the cable stops moving forward, disassemble the sealing assembly and lift the cable to lift the horizontal well fishing device.

[0018] This method is mainly aimed at dealing with problems in the horizontal well section. Therefore, when the horizontal well fishing device is being used, when it reaches a well inclination of 57°-60°, that is, when it reaches the horizontal well section, at this time, it is necessary to provide well pressure through the wellhead circulation device in cooperation with the high-pressure generating device to drive the horizontal well fishing device forward, so that the horizontal well fishing device can fish for the plug ball in the horizontal well section.

[0019] Of course, the fishing method in this method can also fish for other instruments with fishing spears set in the horizontal well section, prevent the instruments from being buried underground, and reduce equipment costs.

[0020] Preferably, in step S4, when the downhole problem type is well leakage, the following steps are executed: N1, the high-pressure generating source continuously builds up pressure in the well through the wellhead circulation device until the well pressure drop reaches 4-5 Mpa; N2, pump a plugging fluid into the well to a preset volume and keep it stable for 2-3 hours. When the downhole problem type is stuck pipe, the following steps are executed: M1, the high-pressure generating source continuously builds up pressure in the well through the wellhead circulation device until the well pressure drops to 4-5 Mpa and then continues to build up pressure for 2-10 min; M2, drive the torque to reverse so that the releasing sub and the plugging sub rotate relative to each other to disengage from each other. When the bypass hole starts to be unobstructed to completely unobstructed, its through-diameter becomes larger and larger, that is, the well pressure will gradually decrease. When the well pressure drops by 4-5 Mpa, the top surface of the piston just passes through the bypass hole, that is, at this time, the bypass hole is in a completely open state. And in the process of dealing with the stuck well in this method, the pressure buildup time of 2-10 min is an empirical value. When the elastic coefficient of the selected spring is different, the size of the bypass hole is different, the provided initial pressure is different, etc., the pressure buildup time needs to be adjusted appropriately. This pressure buildup time is used to determine the sign of the separation of the piston's limiting device from the releasing sub.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] 1. The present invention provides a system and method for dealing with complex problems in a horizontal well section, which systematically integrates a wellhead circulation device, a downhole while-drilling processing device, and a horizontal well fishing device, thereby effectively and safely dealing with complex downhole accidents, especially well leakage and stuck pipe situations occurring in the horizontal well section.

[0023] 2. For the present invention's system for dealing with complex problems in a horizontal well section and its pneumatic transmission system, when complex problems or stuck pipe occur in the horizontal well section and cannot be released by methods such as moving, jarring, or static foaming and reverse circulation is required, the complex processing system in the horizontal well section can perform reverse circulation to retrieve the drill string or instrument above the plugging joint, ensuring the safety of the upper drill string or instrument and preventing further deterioration of the accident, thus winning valuable time for the next milling and reverse circulation or other accident handling.

[0024] 3. For the present invention's system and method for dealing with complex problems in a horizontal well section, when leakage occurs in the horizontal well section, i.e., well leakage, the complex processing system in the horizontal well section can, without pulling out the drill string, timely and effectively perform static plugging and pressure-bearing plugging with high-concentration and large-particle plugging materials multiple times to handle the complex well leakage accident, preventing the occurrence of serious accidents such as blowout, well collapse, and stuck pipe induced by the decrease in liquid level or density during pulling out the drill string, and effectively reducing the number of trips.

[0025] 4. For the present invention's system and method for dealing with complex problems in a horizontal well section, by using a bypass method, the plugging material enters the annulus through the bypass hole for plugging, which can effectively protect various downhole instruments and tools and will not affect their normal operation due to the plugging material. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, form a part of this application, and do not limit the embodiments of the present invention. In the drawings:

[0027] Figure 1 It is a schematic structural diagram of an embodiment provided by the present invention.

[0028] Figure 2 It is a schematic structural diagram of an embodiment provided by the present invention.

[0029] Figure 3 It is a schematic structural diagram of an embodiment provided by the present invention.

[0030] Figure 4 It is a schematic structural diagram of an embodiment provided by the present invention.

[0031] Figure 5 It is a schematic structural diagram of an embodiment provided by the present invention.

[0032] Figure 6 Provided for the present invention Figure 1 Partial structural schematic diagram.

[0033] Marks in the drawings and corresponding component names:

[0034] 1 - Plugging nipple, 2 - Back-off nipple, 3 - Piston, 4 - Elastic member, 5 - Side through-hole, 6 - Stop ring, 7 - Limiting device, 8 - Plug ball, 9 - Three-way pipe, 10 - Sealing cylinder, 11 - Sealing cover, 12 - Rubber core, 13 - Extrusion block, 14 - Core support, 15 - While-drilling treatment device, 16 - Horizontal well fishing device, 17 - Wellhead circulation device, 18 - High-pressure generating source. Specific embodiments

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and are not intended to limit the present invention.

[0036] Embodiment

[0037] A system for handling complex problems in a horizontal well section, comprising a wellhead circulation device 17, a downhole while-drilling treatment device 15, and a horizontal well fishing device 16. The downhole while-drilling treatment device 15 includes a piston 3, a plugging short section 1 with an axial through-hole, and a back-off short section 2 with an axial through-hole. The lower end of the plugging short section 1 is detachably and coaxially connected to the upper end of the back-off short section 2. A side through-hole 5 is formed in the side wall of the plugging short section 1 near the upper end. The piston 3 is coaxially arranged in the through-hole of the plugging short section 1. The outer wall of the upper end of the piston 3 is connected to the inner wall of the plugging short section 1 through an elastic member 4. The elastic member 4 can provide an elastic force to the piston 3 so that the piston 3 has a tendency to slide relative to the plugging short section 1. The lower end of the piston 3 is located in the through-hole of the back-off short section 2. A limiting device 7 is arranged on the shaft section of the piston 3 near the lower end. The limiting device 7 is detachably connected to the back-off short section 2 to limit the rotation of the back-off short section 2. The horizontal well fishing device 16 is used to fish for a plugging ball 8. The horizontal well fishing device 16 has an elastic buckle for cooperating with the fishing spear of the plugging ball 8. The wellhead circulation device 17 has a high-pressure supply port, which is used to be connected to the well pipe to provide forward driving force for the plugging ball 8. In the working state of bypass plugging, the plugging ball 8 pushes the piston 3 to move downward through the pressure provided by the wellhead circulation device 17 so that the upper end face of the piston 3 is located below the side through-hole 5, and the side through-hole 5 is in an open state to inject the plugging liquid. In the working state of back-off, the plugging ball 8 pushes the piston 3 to move downward through the pressure provided by the wellhead circulation device 17 so that the limiting device 7 of the piston 3 is separated from the back-off short section 2, and the back-off short section 2 is in a rotatable state so that the back-off short section 2 can be separated from the plugging short section 1. In the working state of fishing for the plugging ball 8, the horizontal well fishing device 16 cooperates with the plugging ball 8 through the pressure provided by the wellhead circulation device 17 to realize the fishing of the plugging ball 8.

[0038] In this embodiment, the wellhead circulation device 17, the downhole while-drilling processing device 15, and the horizontal well fishing device 16 are systematically integrated to effectively and safely handle complex downhole accidents, especially for well leakage and stuck pipe situations occurring in the horizontal well section. The downhole while-drilling processing device 15 is connected to the downhole drill string, so that installation is avoided when a downhole accident occurs, saving the time for accident handling. When well leakage occurs, a plug ball 8 is manually placed from the wellhead circulation device 17. At this time, pressure is applied to the well by a high-pressure generating source 18. Under the action of the pressure of the plug ball 8, it moves forward along the extension direction of the well. When the plug ball 8 contacts the piston 3, the piston 3 is pushed downward by the plug ball 8 until the top surface of the piston 3 is below the side through hole 5. At this time, the side through hole 5 connects the inside of the leak stoppage nipple 1 with the annulus outside the leak stoppage nipple 1, and a leak stoppage fluid is injected into the well to achieve the effect of downhole leak stoppage. When a stuck well occurs, on the basis of the operation of pushing the piston 3 downward for leak stoppage, pressure is continuously applied to the well to further push the plug ball 8 to move the piston 3 downward until the limit device 7 of the piston 3 is separated from the back-off sub 2. At this time, the drill string can be rotated in the reverse direction to achieve the back-off effect.

[0039] Specifically, both the plugging nipple 1 and the back-off nipple 2 are round tubes. Threads that can cooperate with each other are machined at the lower end of the plugging nipple 1 and the upper end of the back-off nipple 2. The plugging nipple 1 and the back-off nipple 2 are coaxially connected by the threads. The through diameter at the lower end of the plugging nipple 1 is equal to the through diameter at the upper end of the back-off nipple 2. A number of long strips extend radially along the inner wall at the upper end of the back-off nipple 2, and the long axis direction of the long strips is parallel to the axis of the back-off nipple 2. The number of long strips together form a spline groove. The through diameter at the upper end of the plugging nipple 1 is larger than the through diameter at the lower end, thus forming a stepped hole. The side hole 5 is located on the side wall at the upper end of the plugging nipple 1. The piston 3 is generally a round tube in a T shape. The piston 3 is coaxially arranged inside the plugging nipple 1. The diameter of the upper end of the piston 3 is larger than the diameter of the lower end. The upper end of the piston 3 is located in the section with a larger diameter in the plugging nipple 1. The outer wall of the piston 3 contacts the inner wall of the plugging nipple 1 so that the piston 3 blocks the side hole 5. An elastic member 4 is connected to the step surface where the large-diameter section and the small-diameter section of the piston 3 meet. The elastic member 4 is also connected to the step surface where the large-diameter section and the small-diameter section of the plugging nipple 1 meet. The elastic members 4 are provided in a number of pieces and are evenly distributed in the circumferential direction of the piston 3. A number of long strips extend circumferentially along the outer wall at the lower end of the piston 3. The number of long strips form a spline that fits the spline groove. The spline cooperates with the spline groove. In this embodiment, the elastic member 4 is arranged at the upper segment of the piston 3. The elastic member 4 mainly applies an upward axial force to the piston 3 to reset the piston 3. Secondly, the arrangement of the elastic member 4 also has a centering effect on the piston 3, that is, it plays a circumferential limit on the upper segment of the piston 3, while the lower end of the piston 3 is limited by the spline. Thus, when the piston 3 moves downward under force, the movement direction of the piston 3 can be close to the axis of the piston 3, thereby reducing the contact pressure generated between the piston 3 and the plugging nipple 1, allowing the machining requirements for the outer wall of the piston 3 and the inner wall of the plugging nipple 1 to be reduced, and reducing the machining cost.

[0040] In some possible embodiments, when the number of elastic members 4 is one, the elastic member 4 is set as a spring. The spring is sleeved on the piston 3, and both ends of the spring are limited by the stepped surface of the piston 3 and the stepped surface of the plugging short joint 1 respectively. Threads are also machined on the inner wall of the upper end of the plugging short joint 1, and a blocking ring 6 is coaxially assembled on the inner wall of the upper end of the plugging short joint 1. The blocking ring 6 contacts the top end of the piston 3. In this embodiment, the direction of the elastic force provided by the spring lock also depends on the contact areas of the spring with the piston 3 and the plugging short joint 1. During the process of the spring being compressed, the contact areas of the upper and lower ends of the spring with the piston 3 and the plugging short joint 1 will gradually increase. In order to ensure that the direction of the elastic force provided by the spring is close to the axial direction of the piston 3, at least 3 / 4 of the spring coils at the upper and lower ends of the spring are in contact with the piston 3 and the plugging short joint 1. That is, in the initial state, the spring needs to be compressed, which is realized by the blocking ring 6 in this embodiment. By rotating the blocking ring 6, the position of the blocking ring 6 in the plugging short joint 1 can be adjusted, and the specific position of the blocking ring 6 needs to be determined according to the actual situation. For example, using different springs and different weights of the piston 3 will affect the adjustment of the position of the blocking ring 6. Therefore, the specific position of the blocking ring 6 is not limited here.

[0041] In some possible embodiments, the outer wall of the lower end of the piston 3 is slidably connected to the plugging short joint 1, and the sliding direction is along the axial direction of the piston 3. For example, a protrusion can be provided at the lower end of the piston 3, and a groove capable of accommodating the protrusion is provided on the inner wall of the corresponding plugging short joint 1. The length of the groove along the axial direction of the piston 3 is greater than that of the protrusion, so that the protrusion can slide in the groove. When the spline disengages from the spline groove, the piston 3 wants to reset. At this time, the protrusion and the groove play a role in restricting the piston 3 in the circumferential direction, so that the spline and the spline groove can be accurately matched without hindrance. Specifically, the relative position and attitude of the spline groove of the reverse-threaded short joint 2 with respect to the drill tool are fixed. At this time, the position and attitude of the spline groove can be determined by controlling the rotation amount of the drill tool. Thus, after the reverse-threaded short joint 2 is disengaged from the plugging short joint 1, the position and attitude of the spline groove on the reverse-threaded short joint 2 remain the same as before disengagement. At this time, the piston 3 can reach an accurate and unobstructed fit during the process of pushing out the reverse-threaded short joint 2.

[0042] In some possible embodiments, the opening at the upper end of the piston 3 is provided as a cone. The opening at the upper end of the piston 3 needs to be sealed both during leak stoppage and back-off. The traditional openings at the upper end of the piston 3 are all flat openings. The plug ball 8 and the upper top surface of the piston 3 are sealed through planar contact. In this sealing method, the plug ball 8 is prone to skew relative to the piston 3, resulting in a weakened sealing effect. By setting the opening at the upper end of the piston 3 as a cone, the corresponding plug ball 8 should be processed into a shape that matches this cone. This can be directly obtained by those skilled in the art without any objection. After the plug ball 8 and the piston 3 are matched, the conical opening has a circumferential limiting effect on the piston 3, preventing the plug ball 8 from skewing and causing sealing failure. More preferably, the opening at the upper end of the piston 3 is processed into a spherical concave surface. Correspondingly, the sealing surface of the plug ball 8 is set as a corresponding sphere. The cooperation of this structure enables the plug ball 8 to still seal the piston 3 even when skewed, increasing the sealing error tolerance.

[0043] In some possible embodiments, as a specific implementation manner of the wellhead circulation device 17, the wellhead circulation device 17 takes the three-way pipe 9 as the main body. The ports a and b in the three-way pipe 9 are used as the outlet and inlet of the high-pressure source, and the inner wall diameter of the port c is enlarged to form a sealing cylinder 10. A sealing assembly is arranged in the sealing cylinder 10. The outer wall of the port c is processed with threads, and the port c is fitted with a sealing cover 11 through the threads. A through hole coaxial with the port c is opened on the sealing cover 11, and the diameter of the through hole is smaller than that of the port c. The sealing assembly is pressed by the sealing cover 11 in the sealing cylinder 10. In this embodiment, the through hole of the sealing cover 11 is used to pass the cable of the downhole tool. Since this embodiment mainly deals with the problems in the horizontal well section, when the tool travels to the horizontal well section, a certain pressure needs to be provided for the tool to move forward. At this time, the wellhead circulation device 17 needs to work. The cable or wire of the tool passes through the sealing assembly and is located outside the wellhead circulation device 17 to supply current or recover the tool. Due to the existence of the sealing assembly, high pressure can be provided to the well through the port b, thus avoiding the use of the wellhead sealing device. In the presence of the wellhead circulation device 17 in this embodiment, the tool can be put into the well through the port c and enter the downhole through the port a, and the cable or wire is arranged in the sealing cylinder 10 in cooperation with the sealing assembly, making the tool placement process simpler, reducing the construction process, saving construction time, and reducing the construction cost of tool placement.

[0044] In some possible embodiments, the sealing assembly includes a rubber core 12, a core support 14, and a pressing block 13. The core support 14, the rubber core 12, and the pressing block 13 are sequentially located in the sealing cylinder 10 along the axial direction of port c. The rubber core 12 is divided into a first rubber core and a second rubber core. The first rubber core and the second rubber core cooperate to form a cylindrical shape with one end being conical. The first rubber core has a first mating surface, and the second rubber core has a second mating surface. A first annular through groove with an axis along the axial direction of the first rubber core is formed on the first mating surface. Along the axial direction of the first annular through groove, several coaxial first annular grooves are further formed. The diameter of the first annular grooves is larger than the diameter of the first annular through groove. A second annular through groove with an axis along the axial direction of the second rubber core is formed on the second mating surface. Along the axial direction of the second annular through groove, several coaxial second annular grooves are further formed. The diameter of the second annular grooves is larger than the diameter of the second annular through groove. After the first rubber core and the second rubber core are mated, the first annular through groove and the second annular through groove cooperate to form a cylindrical through groove, and the first annular grooves and the second annular grooves cooperate in a one-to-one correspondence to form a cylindrical space. Through the arrangement of the through grooves and the annular grooves, the contact between the rubber core 12 and the cable or wire is a segmented contact. Therefore, the contact surface between the rubber core 12 and the cable or wire is multiple cylindrical surfaces. In this contact situation, the contact surface between the rubber core 12 and the cable or wire is prone to deformation, increasing the resistance to the axial sliding of the cable or wire along the rubber core 12, preventing the cable or wire from sliding within the rubber core 12, and improving the sealing effect.

[0045] In some possible embodiments, the pressing block 13 has a conical concave surface that cooperates with the conical shape at one end of the rubber core 12. The pressing block 13 serves as a pressure transmission component in this embodiment. In this embodiment, through the setting of the conical concave surface, the contact area between the pressing block and the rubber core 12 is increased, making the pressure transmission more uniform. The pressure of the rubber core 12 on the cable or wire is more thorough in the axial direction of the rubber core 12, improving the sealing effect.

[0046] In some possible embodiments, the horizontal well fishing device 16 includes a fishing unlocker. The unlocker has an unlocking outer cylinder. A wire passing hole for passing a cable or wire is formed along the axial direction on the side wall of the unlocking outer cylinder. The wire passing hole penetrates the unlocking outer cylinder along the unlocker. A locking ring is connected to the unlocking outer cylinder by bolts. The locking ring is in the shape of an arc-shaped plate, and the curvature of the arc is equal to the outer surface curvature of the unlocking outer cylinder. Protrusions are provided on the inner wall of the locking ring. The protrusions pass through the opening of the unlocking outer cylinder and are located inside the unlocking outer cylinder. After the locking ring is assembled, due to the existence of the opening on the unlocking outer cylinder, slight deformation will occur, generating external stress. At this time, the locking ring is in a tensioned state and is prone to deformation to produce edges, which is not conducive to the advancement of the unlocking outer cylinder in the well. By providing the protrusions, the protrusions can limit the deformation of the unlocking outer cylinder, that is, making the unlocking outer cylinder more inclined to generate internal stress during the assembly process, thereby allowing the locking ring to be assembled more tightly with the unlocking outer cylinder to ensure the service life of the locking ring.

[0047] A method for processing complex problems in horizontal well sections, using the device for processing complex problems in horizontal well sections in the above embodiment to perform downhole undercutting, comprises the following steps:

[0048] S1, make preparations before reverse threading, find out the inner diameters of the water holes of all drilling tools in the well, and select matching plugging balls 8 according to the inner diameters of the water holes of the drilling tools and the water holes of the piston 3, and check the fishing spear of the plugging ball 8 and the plugging ball 8 in detail to ensure that there are no bumps or scratches on the sealing ball surface.

[0049] S2, check whether the self-locking mechanism and elastic reset of the blocking ball 8 are intact by pressing it on the ground

[0050] S3, carefully measure the maximum outer diameter of the plugging ball 8, which should be 3mm smaller than the smallest water hole drilling tool in the well to ensure that it can be successfully salvaged.

[0051] S4, assemble and connect the wellhead circulation device 17 at the wellhead drilling tool and configure the high-pressure generating source 18, drop the plugging ball 8 from the wellhead circulation device 17, start pumping the plugging ball 8 to the water hole position of the piston 3, and judge the forward distance of the plugging ball 8 in the well based on the speed of 200m / min.

[0052] S5, after the blocking ball 8 reaches the water hole of the piston 3, the pump is turned on to hold the pressure. Under the action of the pump pressure, the blocking ball 8 pushes the piston 3 downward. When the upper end surface of the piston 3 reaches the short-section bypass hole 5, the pump pressure begins to drop. When the two side holes 5 are completely connected, the pump pressure will drop by 4 to 5 MPa.

[0053] S6, at this time, the piston 3 continues to move downward under the action of the pump pressure, and waits for 2 to 10 minutes to complete the complete separation of the key and keyway of the upper and lower short sections and the key and keyway of the piston 3, and successfully release the key. The length of time depends on the pressure provided, that is, the travel speed of the piston. In the case of very high pressure, the waiting time may be less than 2 minutes, and in the case of low pressure, the waiting time may be more than 10 minutes. Those skilled in the art can select a suitable waiting time according to the specific pressure.

[0054] S7, the pump needs to be turned on for a second time to check the debonding condition. After the pump is turned on, the pump pressure is the pump pressure after the bypass hole 5 is opened and dropped, and it does not change again, indicating that the debonding is successful. Otherwise, it needs to be analyzed and the cause is found out before proceeding again.

[0055] S8, at this time, the drill bit is rotated in the opposite direction to separate the upper and lower short sections, thereby achieving the purpose of reverse cutting.

[0056] S9, if the ball throwing cannot complete the reverse operation, it is necessary to restore the water hole to be unobstructed. With the cooperation of the wellhead circulation device 17, the blocking ball 8 is unlocked by unlocking the salvage device and then salvaged from the horizontal section of the bottom of the well to the ground to ensure the unobstructed water hole of the drilling tool and facilitate accident handling.

[0057] A method for processing complex problems in horizontal well sections, using the device for processing complex problems in horizontal well sections in the above embodiment to perform underground bypass plugging, comprises the following steps:

[0058] T1. Make preparations before plugging the leak, find out the inner diameters of the water holes of all the drilling tools in the well, and select the matching plugging ball 8 according to the inner diameters of the water holes of the drilling tools and the water holes of the downhole processing device 15. Check in detail the spear of the plugging ball 8, the plugging ball 8, the limit device 7, and the self-locking mechanism to ensure that the sealing surface of the plugging ball 8 is intact and free of bumps and scratches.

[0059] T2. Measure the maximum outer diameter of the plugging ball 8 in detail, which should be 3mm smaller than the smallest water hole drilling tool in the well to ensure that it can be successfully salvaged.

[0060] T3, assemble the horizontal well fishing device 16 on the ground and connect it to the wired winch, ensure that the screws at each connection are tightened, the fishing device claws are elastic and flexible to reset, assemble and connect the wellhead circulation device 17 at the wellhead drilling tool and configure the high-pressure generator 18.

[0061] At T4, the plugging ball 8 is put into the wellhead circulation device 17, and the pump is turned on to send the plugging ball 8 to the horizontal section at the bottom of the well. The time for the plugging ball 8 to reach the water hole position of the downhole processing device 15 is accurately calculated based on the displacement and the drilling tool volume. When a quarter of the calculated time remains, the displacement is adjusted to less than 12L / S to reduce the impact damage of the plugging ball 8 on the piston 3 and itself.

[0062] T5, the blocking ball 8 reaches the water hole position of the piston 3 to seal the water hole, and the piston 3 is pushed downward under the action of the pump pressure. After the upper end surface of the piston 3 reaches the bypass hole 5 position, the pump pressure begins to drop. After it is completely penetrated, the pump pressure will drop by 4 to 5 MPa.

[0063] T6, when the circumferential structure of the blocking ball 8 reaches the upper end surface of the blocking ring, it prevents the blocking ball 8 from continuing to move downward, and the piston 3 can only fully open the bypass hole 5 and cannot move downward further, thereby preventing the occurrence of the key-off and back-off phenomenon.

[0064] T7, at this time, the plugging slurry will enter the horizontal section through the bypass hole 5 to achieve static plugging, pressure plugging or other plugging methods (pump the plugging slurry with a displacement of 12L / S, and timely observe and record the pump pressure change values before and after the bypass hole 5 is opened and when the plugging slurry passes through the bypass hole 5, so as to judge the working status of the bypass plugging system).

[0065] T8, if it is pressure plugging, close the sealing ring at this time, slowly pump in the plugging slurry with a small displacement (displacement of 12L / S), pump in the appropriate amount of plugging slurry by calculation, stabilize the pressure and wait for 2 to 3 hours. If the pressure in the annulus is stable and does not drop, it means that the plugging is successful, otherwise continue.

[0066] T9. During the plugging process, the plugging ball 8 blocks the water eye, preventing the plugging slurry from entering the lower drill string, effectively protecting various downhole instruments and tools. After the pump is stopped, the piston 3 moves upward under the action of the elastic member 4, and the side through hole 5 is closed.

[0067] T10. After the plugging is completed, open the blowout preventer, pull out the drill string to a safe section more than 50 m, and start the pump to thoroughly circulate and clean the residual plugging material in the drill pipe to prevent it from entering the instrument, screw or other drill tools after the main water eye is opened.

[0068] T11. Lower the connected unlocking fishing tool from the wellhead circulation device 17 with the cooperation of a wireline winch, controlling the lowering speed at 150 m / min to prevent damage to the fishing spear and the unlocking fishing tool due to impact.

[0069] T12. When the unlocking fishing tool reaches a well inclination of 57° - 60°, stop advancing. At this time, rotate the sealing cover 11 of the wellhead circulation device 17 to complete the sealing of the cable, rubber core 12, and the gap of the cylinder block to prevent mud leakage. After starting the pump, control the discharge at 4 - 6 L / S, and the mud pushes the fishing tool to continue advancing in the horizontal section.

[0070] T13. When the cable stops advancing, it means that the fishing tool has reached the fishing position and successfully docked with the downhole instrument and the fishing spear of the plugging ball 8. Immediately stop the pump and rotate the sealing cover 11 to relieve pressure, and then raise the cable.

[0071] T14. When starting to raise, control the speed at 10 m / min and pay attention to observing the change of the winch tension gauge. If the tension exceeds 30 KN and does not decrease but continues to rise, immediately stop raising, which means the instrument is stuck and cannot be fished, and lower the unlocking tool to unlock and withdraw.

[0072] T15. When starting to raise, if the tension does not exceed 20 KN and then slowly decreases during the raising process, it means the fishing is successful. At this time, raise at a speed of 30 m / min. After reaching the vertical well section, slowly increase the raising speed to 80 - 150 m / min.

[0073] T16. When the raising distance is 300 mm from the wellhead, quickly reduce the raising speed to 20 m / min. When the distance is 100 mm from the wellhead, immediately stop raising, remove the sealing cover 11, and slowly raise the cable at a speed of 10 m / min. When the fishing tool reaches the wellhead and enters the sealing cylinder 10, it automatically ejects all the sealing components. Cover the wellhead to prevent the components from falling into the well.

[0074] T17. Take out the unlocking fishing tool and the plugging ball 8 from the sealing cylinder 10 of the wellhead circulation device 17, and remove the wellhead circulation device 17 at the wellhead.

[0075] In the present invention, both the fishing device and the plugging ball can adopt existing plugging balls and fishing devices.

[0076] The specific embodiments described above further elaborate on the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only for the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for handling complex problems in horizontal well sections, characterized in that, It includes a wellhead circulation device (17), a downhole while-drilling treatment device (15) and a horizontal well fishing device (16); The downhole while-drilling treatment device (15) includes a piston (3), a plugging nipple (1) with an axial through-hole and a back-off nipple (2) with an axial through-hole. The lower end of the plugging nipple (1) is detachably and coaxially connected to the upper end of the back-off nipple (2). A side through-hole (5) is formed in the side wall of the plugging nipple (1) near the upper end; The piston (3) is coaxially arranged in the through-hole of the plugging nipple (1). The outer wall of the upper end of the piston (3) is connected to the inner wall of the plugging nipple (1) through an elastic member (4). The elastic member (4) can provide an elastic force to the piston (3) so that the piston (3) has a tendency to slide relative to the plugging nipple (1). The lower end of the piston (3) is located in the through-hole of the back-off nipple (2). A limiting device (7) is arranged on the shaft section of the piston (3) near the lower end. The limiting device (7) is detachably connected to the back-off nipple (2) to limit the rotation of the back-off nipple (2); The horizontal well fishing device (16) is used to fish a plug ball (8), and the horizontal well fishing device (16) has an elastic buckle for cooperating with the fishing spear of the plug ball (8); The wellhead circulation device (17) has a high-pressure supply port, which is used to connect with the well pipe to provide forward driving force for the plug ball (8). A sealing component for sealing the cable is also arranged in the wellhead circulation device (17); In the working state of bypass plugging, the plug ball (8) pushes the piston (3) to move downward through the pressure provided by the wellhead circulation device (17) so that the upper end face of the piston (3) is located below the side through-hole (5), and the side through-hole (5) is in an open state to inject the plugging liquid; In the working state of back-off, the plug ball (8) pushes the piston (3) to move downward through the pressure provided by the wellhead circulation device (17) so that the limiting device (7) of the piston (3) is separated from the back-off nipple (2), and the back-off nipple (2) is in a rotatable state so that the back-off nipple (2) can be separated from the plugging nipple (1); In the working state of fishing the plug ball (8), the horizontal well fishing device (16) cooperates with the plug ball (8) through the pressure provided by the wellhead circulation device (17) to fish the plug ball (8); Among them, the wellhead circulation device (17) includes a tee pipe (9) body, a sealing component and a sealing cover (11); The diameter of the port a of the tee pipe (9) body is enlarged to form a sealing cylinder (10). The port b of the tee pipe (9) body serves as the high-pressure supply port, and the port b is coaxial with the port a. The port c of the tee pipe (9) body is used to connect to a high-pressure generating source (18); The sealing component is arranged in the sealing cylinder (10); The sealing cover (11) has a threaded connection end adapted to the outer wall of the port a. The sealing cover (11) is sleeved on the outer wall of the port a and is in threaded cooperation. The sealing component is pressed into the sealing cylinder (10) through the sealing cover (11); The sealing assembly includes a rubber core (12), a core support (14) and an extrusion block (13). The core support (14), the rubber core (12) and the extrusion block (13) are coaxially arranged in the sealing cylinder (10) in sequence; The rubber core (12) includes a first rubber core and a second rubber core; The first rubber core has a first contact plane, and a first cable groove penetrating along the axial direction of the sealing cylinder (10) is formed on the first contact plane. Along the axial direction of the sealing cylinder (10), the first cable groove has several enlarged diameter sections; The second rubber core has a second contact plane, and a second cable groove penetrating along the axial direction of the sealing cylinder (10) is formed on the second contact plane. Along the axial direction of the sealing cylinder (10), the second cable groove has several enlarged diameter sections; When the first contact plane is attached to the second contact plane, the enlarged diameter sections of the first cable groove correspond to the enlarged diameter sections of the second cable groove one by one. The extrusion block (13) is located between the rubber core (12) and the sealing cover (11); One end of the rubber core (12) close to the sealing cover (11) is set to be conical, and the extrusion block (13) has a conical concave surface adapted to the conical shape; The through hole of the plugging nipple (1) is a stepped hole, and the through diameter of the upper end of the plugging nipple (1) is larger than that of the lower end; The radial cross-section of the piston (3) is T-shaped, and the diameter of the upper end of the piston (3) is larger than that of the lower end; One end of the elastic member (4) is connected to the lower end surface of the large diameter section of the piston (3), and the other end is connected to the lower end surface of the large through diameter of the plugging nipple (1); The opening at the upper end of the piston (3) is set to be conical, and the diameter of the upper end of the cone is larger than that of the lower end of the cone.

2. The complex problem processing system for a horizontal well section according to claim 1, characterized in that The elastic member (4) is a spring, and the elastic member (4) is sleeved on the small diameter section of the piston (3).

3. The horizontal well section complex problem processing system according to claim 2, wherein A blocking ring (6) is threadedly engaged with the upper end of the through hole of the plugging nipple (1), and the blocking ring (6) contacts the upper end of the piston (3) to form an axial limit for the piston (3).

4. A method for dealing with complex problems in a horizontal well section, which applies the horizontal well section complex problem processing system described in any one of claims 1 to 3, characterized in that, It includes the following steps: S1, assemble the wellhead circulation device (17), connect the wellhead with the wellhead circulation device (17) and configure a high-pressure generating source (18) for the wellhead circulation device (17); S2, put the plugging ball (8) into the well through the wellhead circulation device (17); S3, start the high-pressure generating source (18) to provide well pressure in the well so that the plugging ball (8) contacts the piston (3); S4, according to the type of downhole problems, provide well pressure through the wellhead circulation device (17) to build up pressure in the well so that the plugging ball (8) pushes the piston (3) to move downward; S5, close the high-pressure generating source (18), put the horizontal well fishing device (16) through the wellhead circulation device (17). When the horizontal well fishing device (16) reaches a well inclination of 57° - 60°, stop moving forward. Seal the cable of the horizontal well fishing device (16) through the sealing assembly, start the high-pressure generating source (18), and control the displacement at 4 - 6 L / S to push the horizontal well fishing device (16) to move forward in the horizontal well section; S6, when the cable stops moving forward, disassemble the sealing assembly and lift the cable to lift the horizontal well fishing device (16).

5. A method for dealing with complex problems in a horizontal well section according to claim 4, characterized in that, In the step S4, when the downhole problem type is well leakage, the following steps are executed: N1, the high-pressure generating source (18) continuously applies pressure to the well through the wellhead circulation device (17) until the pressure drop in the well reaches 4 - 5 Mpa; N2, pump the lost circulation fluid into the well to a preset volume, and maintain the pressure for 2 - 3 hours; When the downhole problem type is stuck pipe, the following steps are executed: M1, the high-pressure generating source (18) continuously applies pressure to the well through the wellhead circulation device (17) until the pressure in the well drops to 4 - 5 Mpa and then continues to apply pressure for 2 - 10 minutes; M2, drive the torque to reverse so that the releasing sub (2) and the lost circulation sub (1) rotate relative to each other to disengage from each other.

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