A completion method for a wellbore of an ultra-deep horizontal well

Abstract

This application relates to the technical field of oil well exploitation, and specifically relates to a completion method for a wellbore of an ultra-deep horizontal well, which is completed by a pre-set pipe string and a tie-back pipe string, and includes the following steps: Step a, lower the pre-set pipe string, and use the drill pipe to send the multi-functional releasing tool, the drill bit, the tie-back barrel, multiple high-torsion-resistant oil pipes and multiple high-torsion-resistant soluble screen pipes to the preset well depth; Step b, after the pre-set pipe string reaches the position, apply positive pressure with the drill pipe, and separate the multi-functional releasing tool from the tie-back barrel, so that the tie-back barrel together with multiple high-torsion-resistant oil pipes, multiple high-torsion-resistant soluble screen pipes and the drill bit remain at the bottom of the well; Step c, lower the tie-back pipe string until the sealing nipple at the bottom of the oil pipe is tied back to the tie-back barrel of the pre-set pipe string and then stop; Step d, set the packer of the tie-back pipe string to complete the well completion. This application solves the problems of long simulated wellbore cleaning time, difficult pipe string lowering, and inability to perform conventional well completion caused by the horizontal wellbore.

Description

Technical Field

[0001] This application relates to the technical field of oil well exploitation, and specifically relates to a completion method for a wellbore of an ultra-deep horizontal well. Background Art

[0002] Horizontal wells can effectively improve the productivity of a single well. However, for ultra-deep horizontal wells with a depth exceeding 4,000 meters, the drilling and completion construction is difficult. Especially for complex reservoirs with developed fractures and strong heterogeneity, further reservoir stimulation is required to achieve efficient development.

[0003] Currently, for reservoirs with characteristics such as pressure sensitivity, a narrow safety density window, easy blowout and leakage, high well control risk, and difficulty in carrying cuttings by drilling fluid, the conventional completion method is to use the hanging irrigation method to achieve dynamic balance in the well. The disadvantages of this method are extremely complex processes and long operation cycles.

[0004] In addition, with the passage of time, the vertical depth of the horizontal well increases significantly, the horizontal section continues to extend, and the friction of the tubing string in the open hole section of the completion section is large, making it prone to deformation, and even buckling deformation, resulting in the situation where the tubing string cannot be lowered to the designated position. Summary of the Invention

[0005] The purpose of this application is to provide a completion method for a wellbore of an ultra-deep horizontal well in view of the deficiencies in the prior art, and to realize the wellbore completion process by lowering two trips of tubing strings.

[0006] This application provides a completion method for a wellbore of an ultra-deep horizontal well, which is completed by a pre-set tubing string and a tie-back tubing string. The pre-set tubing string includes a drill pipe, a multi-functional release joint, a drill bit, a tie-back barrel, a plurality of high torsional resistance tubing, and a plurality of high torsional resistance soluble screens; the plurality of high torsional resistance soluble screens are arranged at intervals along the exploitation direction, and adjacent two high torsional resistance soluble screens are connected by a high torsional resistance tubing. The high torsional resistance soluble screen at the end is also connected with a high torsional resistance tubing, and the high torsional resistance tubing at the end is connected with the drill bit. The drill pipe is connected with one end of the tie-back barrel through the multi-functional release joint, and the other end of the tie-back barrel is connected with the high torsional resistance soluble screen at the beginning end. The tie-back barrel is also provided with a ball seat; the tie-back tubing string includes a tubing, a packer sleeved on the outer peripheral side of the tubing, and a sealing nipple fixedly connected to the bottom end of the tubing; the completion method includes the following steps: Step a, lower the pre-set tubing string, and use the drill pipe to send the multi-functional release joint, the drill bit, the tie-back barrel, the plurality of high torsional resistance tubing, and the plurality of high torsional resistance soluble screens to the preset well depth, and then drop a ball so that the ball is placed in the ball seat of the tie-back barrel to achieve plugging; Step b, after the pre-set tubing string reaches the position, the drill pipe applies positive pressure to separate the multi-functional release joint from the tie-back barrel, so that the tie-back barrel, together with the plurality of high torsional resistance tubing, the plurality of high torsional resistance soluble screens, and the drill bit, remains at the bottom of the well; Step c, lower the tie-back tubing string until the sealing nipple at the bottom end of the tubing is tied back to the tie-back barrel of the pre-set tubing string and then stop; Step d, set the packer of the tie-back tubing string to complete the well completion.

[0007] Among them, an anchoring and sealing mechanism can be provided at the upper end of the back connection barrel, and the drill pipe rotates forward to release the anchoring and sealing mechanism, thus separating from the multi-functional releasing tool of the drill pipe; the high torsional resistance soluble screen pipe can include a pipe body and a plurality of hole plugs. A plurality of thread holes arranged at intervals are formed on the outer peripheral side of the pipe body, internal threads are formed on the inner side surfaces of the thread holes, and external threads matching the internal threads are formed on the outer peripheral sides of the hole eyes of each hole plug. Each hole plug is placed into one of the hole eyes of the pipe body to form a seal; the high torsional resistance oil pipe can include an upper oil pipe and a lower oil pipe that are connected to each other. The bottom end of the upper oil pipe and the top end of the lower oil pipe are fixedly connected by a threaded structure; the threaded structure can include a first thread group and a second thread group formed on the outer side of the bottom end of the upper oil pipe and a first thread groove group and a second thread groove group formed on the outer side of the top end of the lower oil pipe. The first thread group and the second thread group are staggered in the height direction, and the first thread groove group and the second thread groove group are staggered in the height direction. In the assembled state, the first thread group is snap-connected to the first thread groove group, and the second thread group is snap-connected to the second thread groove group; both the first thread group and the second thread group can include a plurality of thread bars arranged at intervals in the height direction, and the cross-sectional shape of each thread bar is trapezoidal. Both the first thread groove group and the second thread groove group include a plurality of thread grooves arranged at intervals in the height direction, and the cross-sectional shape of each thread groove is trapezoidal; the threaded structure can further include a first inclined surface formed at the bottom end of the upper oil pipe and a second inclined surface formed at the top end of the lower oil pipe. In the assembled state, the first inclined surface abuts against the second inclined surface.

[0008] A completion method for the wellbore of an ultra-deep horizontal well in this application has the following beneficial effects:

[0009] (1) Through reasonable process design, by using high torsional resistance oil pipes and high torsional resistance soluble screen pipes, the problems of long simulated wellbore cleaning time, difficult pipe string lowering, and inability to perform conventional well completion caused by the horizontal wellbore are solved;

[0010] (2) The process operation procedure is simple, solving the problem of difficult oil pipe lowering. At the same time, it can fully displace the heavy mud at the bottom of the well and meet the requirements of later reservoir stimulation and oil and gas production processes;

[0011] (3) This process is suitable for horizontal wells or large-angle inclined wells with difficult pipe string lowering and inability to perform conventional well completion. It can reduce the risk of backfilling and sidetracking in ultra-deep horizontal wells or inclined wells. It can achieve reaming while lowering the pipe string when encountering resistance during the pipe string lowering process, reducing the number of wellbore cleaning times, effectively saving the well completion cycle and cost, and reducing the possibility of complex accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The embodiments in the drawings do not constitute any limitation to this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the following drawings.

[0013] Figure 1It is a schematic structural diagram after the pre - installed string enters the well in this application's ultra - deep horizontal well.

[0014] Figure 2 It is a schematic structural diagram after the tie - back string enters the well in this application's ultra - deep horizontal well.

[0015] Figure 3 It is a schematic structural diagram of the high - torque - resistant soluble screen pipe in this application.

[0016] Figure 4 It is a schematic structural diagram of the hole plug in this application.

[0017] Figure 5 It is a schematic structural diagram of the high - torque - resistant tubing in this application.

[0018] Figure 6 It is Figure 5 The enlarged view of the A position in

[0019] Figure 7 It is Figure 5 The enlarged view of the B position in

[0020] Figure 8 It is Figure 5 The enlarged view of the C position in

[0021] Reference numerals: casing 1, high - torque - resistant tubing 2, upper tubing 21, lower tubing 22, first thread group 201, second thread group 202, first thread groove group 203, second thread groove group 204, first inclined plane 205, second inclined plane 206, high - torque - resistant soluble screen pipe 3, threaded hole 31, hole plug 32, external thread 33, drill bit 4, pre - installed string 5, tie - back barrel 6, tie - back string 7, packer 8. Specific embodiments

[0022] The present application will be further described in conjunction with the following embodiments.

[0023] The specific implementation of a completion method for the wellbore of the ultra - deep horizontal well in this application is completed by the pre - installed string 5 and the tie - back string 7.

[0024] In combination with Figure 1, the pre - installed string 5 includes drill pipes, a multi - functional releasing tool, a drill bit 4, a tie - back barrel 6, multiple high - torsional - resistance oil pipes 2 and multiple high - torsional - resistance soluble screen pipes 3. The multiple high - torsional - resistance soluble screen pipes 3 are arranged at intervals along the exploitation direction. Adjacent two high - torsional - resistance soluble screen pipes 3 are connected through a high - torsional - resistance oil pipe 2. The high - torsional - resistance soluble screen pipe 3 at the end is also connected with a high - torsional - resistance oil pipe 2. It can be understood that the multiple high - torsional - resistance oil pipes 2 and the multiple high - torsional - resistance soluble screen pipes 3 are connected to each other at intervals. The high - torsional - resistance oil pipe 2 at the end is connected to the drill bit 4. The drill pipe is connected to one end of the tie - back barrel 6 through the multi - functional releasing tool, and the other end of the tie - back barrel 6 is connected to the high - torsional - resistance soluble screen pipe 3 at the beginning. In this embodiment, the tie - back barrel 6 is also provided with a ball seat. As a preferred solution, the ball seat can be a blind - plate ball seat, and it can also be selected according to actual requirements. It should be noted that the multiple high - torsional - resistance oil pipes 2, the multiple high - torsional - resistance soluble screen pipes 3 and the tie - back barrel 6 together constitute the pre - installed completion string left in the bottom of the well.

[0025] In this embodiment, an anchoring and sealing mechanism is arranged at the upper end of the tie - back barrel 6. The drill pipe rotates forward to release the anchoring and sealing mechanism, so as to separate from the multi - functional releasing tool of the drill pipe. When lowering the pre - installed string 5, the drill pipe, the multi - functional releasing tool and the tie - back barrel 6 will be lowered into the casing 1 of the oil well. By rotating the drill pipe forward, the multi - functional releasing tool releases the anchoring and sealing mechanism of the tie - back barrel 6, so that the multi - functional releasing tool is released from the tie - back barrel 6. Combining Figure 2 , the tie - back string 7 includes an oil pipe, a packer 8 sleeved on the outer peripheral side of the oil pipe and a sealing nipple fixedly connected to the bottom end of the oil pipe. It should be noted that the packer 8 is a conventional packer, and the sealing nipple can be tied - back with the tie - back barrel 6. Both the sealing nipple and the tie - back barrel 6 can adopt conventional technologies. Specifically, threads are arranged at both the upper and lower ends of the sealing nipple, and the tie - back barrel 6 is also provided with threads for sealing connection.

[0026] Combining Figure 3 and Figure 4 , in this embodiment, the high - torsional - resistance soluble screen pipe 3 includes a pipe body and multiple hole plugs 32. Multiple spaced - apart threaded holes 31 are formed on the outer peripheral side of the pipe body. The inner side surface of the threaded hole 31 forms an internal thread, and the outer peripheral side of each hole forms an external thread 33 matching the internal thread. Each hole plug 32 is placed into one of the holes of the pipe body to form a seal. It should be noted that the hole plug 32 is provided with a through - hole and a soluble substance located in the through - hole. The hole plug 32 can block the hole of the pipe body to temporarily close the hole, meeting the need of screen - pipe completion and displacement washing in horizontal wells. After the soluble substance of the hole plug 32 dissolves, the flow - through capacity of the pipe body can be restored, meeting the production requirements. At the same time, the high - torsional - resistance soluble screen pipe 3 can also play a role in supporting the wellbore, making displacement washing simpler and with lower risks, and being suitable for use in ultra - deep high - pressure oil wells.

[0027] In order to improve the impact resistance of the high - torsional - resistance oil pipe 2. Combining Figure 5, the high torsional resistance tubing 2 includes an upper tubing 21 and a lower tubing 22 that are connected to each other. The bottom end of the upper tubing 21 and the top end of the lower tubing 22 are fixedly connected by a thread structure. The thread structure includes a first thread group 201 and a second thread group 202 formed on the outer side of the bottom end of the upper tubing 21, and a first thread groove group 203 and a second thread groove group 204 formed on the outer side of the top end of the lower tubing 22. Combine Figure 6 , the first thread group 201 and the second thread group 202 are staggered in the height direction, and the first thread groove group 203 and the second thread groove group 204 are staggered in the height direction. In the assembled state, the first thread group 201 is snap-connected to the first thread groove group 203, and the second thread group 202 is snap-connected to the second thread groove group 204. By staggering the two sets of engaging mechanisms in the height direction, the two engaging surfaces can evenly bear the impact, thereby sharing the load, making the force more uniform, avoiding excessive stress concentration, thereby improving the connection strength between the upper tubing 21 and the lower tubing 22, and thus enhancing the torsional resistance ability of the high torsional resistance tubing 2. As a preferred solution, both the first thread group 201 and the second thread group 202 include a plurality of thread bars arranged at intervals in the height direction, and the cross-sectional shape of each thread bar is trapezoidal. Both the first thread groove group 203 and the second thread groove group 204 include a plurality of thread grooves arranged at intervals in the height direction, and the cross-sectional shape of each thread groove is trapezoidal. This structure can improve the biting force and further prevent the upper tubing 21 and the lower tubing 22 from separating or the connection from breaking. In addition, combine Figure 7 and Figure 8 , the thread structure further includes a first inclined surface 205 formed at the bottom end of the upper tubing 21 and a second inclined surface 206 formed at the top end of the lower tubing 22. The setting positions of the first inclined surface 205 and the second inclined surface 206 can be seen in Figure 4 and Figure 5 The positions shown. There are two sets of the first inclined surface 205 and the second inclined surface 206. The first group is located above the first thread group 201, and the second group is located below the second thread group 202. In the assembled state, the first inclined surface 205 abuts against the second inclined surface 206. The mutual cooperation of the first inclined surface 205 and the second inclined surface 206 can prevent the upper tubing 21 from rotating relative to the lower tubing 22, thereby enhancing the working stability. It can also further share the impact force and further improve the working stability and connection strength

[0028] A completion method for a wellbore of an ultra-deep horizontal well in this application includes the following steps:

[0029] First step: Lower the pre - installed string 5, and use the drill pipe to send the multi - functional release joint, bit 4, tie - back barrel 6, multiple high - torsional - resistance tubing 2, and multiple high - torsional - resistance soluble screen pipes 3 to the preset well depth. During the lowering process, use the automatic choke control system and back - pressure compensation system in the existing technology to automatically compensate the liquid level, so as to make the well control risk controllable. After the pre - installed string 5 reaches the position, drop a ball. After the ball is placed in the ball seat, plugging is achieved.

[0030] Second step: After the pre - installed string 5 reaches the position, apply positive pressure with the drill pipe, and the multi - functional release joint is separated from the tie - back barrel 6, so that the tie - back barrel 6, together with multiple high - torsional - resistance tubing 2, multiple high - torsional - resistance soluble screen pipes 3, and bit 4, remains at the bottom of the well. The use of high - torsional - resistance tubing 2 and high - torsional - resistance soluble screen pipes 3 solves the problems of long simulated well - flushing time, difficult string lowering, and inability to perform conventional well completion caused by the horizontal wellbore.

[0031] Third step: Lower the tie - back string 7 until the seal nipple at the bottom of the tubing is tied back to the tie - back barrel 6 of the pre - installed string 5 and then stop. It should be noted that during the lowering process, it is necessary to perform gas - tight sealing, trial back - insertion, length matching, and lower downhole safety valves for each tubing until the back - insertion is in place.

[0032] Fourth step: The packer 8 of the tie - back string 7 is set, and the well completion is completed.

[0033] The well - completion method for the ultra - deep horizontal wellbore in this embodiment, through reasonable process design, uses high - torsional - resistance tubing and high - torsional - resistance soluble screen pipes, and solves the problems of long simulated well - flushing time, difficult string lowering, and inability to perform conventional well completion caused by the horizontal wellbore. The process operation procedure is simple, solves the problem of difficult tubing lowering, and at the same time can achieve full displacement of the heavy mud at the bottom of the well, and meets the requirements of later reservoir stimulation and oil - gas production technology. This process is suitable for horizontal wells or large - angle inclined wells with difficult string lowering and inability to perform conventional well completion, can reduce the backfill sidetracking risk of ultra - deep horizontal wells or inclined wells, can achieve side reaming while lowering the string when encountering resistance during the string lowering process, reduce the number of well - flushing times, effectively save the well - completion cycle and cost, and reduce the possibility of complex accidents.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A completion method for a wellbore of an ultra-deep horizontal well, characterized in that The completion method is completed by a pre - installed string and a tie - back string. The pre - installed string includes a drill pipe, a multi - function release tool, a drill bit, a tie - back barrel, a plurality of high - torsional - resistance tubing strings, and a plurality of high - torsional - resistance soluble screen pipes; The plurality of high - torsional - resistance soluble screen pipes are arranged at intervals along the production direction. One high - torsional - resistance tubing string is used to connect between two adjacent high - torsional - resistance soluble screen pipes. A high - torsional - resistance tubing string is also connected to the high - torsional - resistance soluble screen pipe at the end. The high - torsional - resistance tubing string at the end is connected to the drill bit. The drill pipe is connected to one end of the tie - back barrel through the multi - function release tool. The other end of the tie - back barrel is connected to the high - torsional - resistance soluble screen pipe at the beginning. A ball seat is also provided on the tie - back barrel; The tie - back string includes a tubing string, a packer sleeved on the outer peripheral side of the tubing string, and a sealing nipple fixedly connected to the bottom end of the tubing string; The completion method includes the following steps: Step a: Lower the pre - installed string so that the drill pipe sends the multi - function release tool, the drill bit, the tie - back barrel, the plurality of high - torsional - resistance tubing strings, and the plurality of high - torsional - resistance soluble screen pipes to the preset well depth. Then, drop a ball so that the ball is placed in the ball seat of the tie - back barrel to achieve sealing; Step b: After the pre - installed string reaches the position, the drill pipe applies positive pressure to separate the multi - function release tool from the tie - back barrel, so that the tie - back barrel, together with the plurality of high - torsional - resistance tubing strings, the plurality of high - torsional - resistance soluble screen pipes, and the drill bit, remain at the bottom of the well; Step c: Lower the tie - back string until the sealing nipple at the bottom end of the tubing string is tied back to the tie - back barrel of the pre - installed string and then stop; Step d: The packer of the tie - back string is set, and the well completion is completed.

2. The completion method of a wellbore of an ultra-deep horizontal well according to claim 1, characterized in that, An anchoring and sealing mechanism is provided at the upper end of the tie - back barrel. The drill pipe rotates forward to release the anchoring and sealing mechanism and thus separates from the multi - function release tool of the drill pipe.

3. The completion method of a wellbore of an ultra-deep horizontal well according to claim 1, characterized in that, The ball seat is a blind - plate ball seat.

4. A completion method for a wellbore of an ultra-deep horizontal well according to any one of claims 1-3, characterized in that, The high - torsional - resistance soluble screen pipe includes a pipe body and a plurality of hole plugs. A plurality of spaced - apart threaded holes are formed on the outer peripheral side of the pipe body. An internal thread is formed on the inner side surface of the threaded hole. An external thread matching the internal thread is formed on the outer peripheral side of the hole eye of each hole plug. Each hole plug is placed into one of the hole eyes of the pipe body to form a seal.

5. A completion method for a wellbore of an ultra-deep horizontal well according to any one of claims 1-3, characterized in that, The high - torsional - resistance tubing string includes an upper tubing string and a lower tubing string that are connected to each other. The bottom end of the upper tubing string is fixedly connected to the top end of the lower tubing string by a thread structure.

6. A completion method for a wellbore of an ultra-deep horizontal well according to claim 4, characterized in that, The high - torsional - resistance tubing string includes an upper tubing string and a lower tubing string that are connected to each other. The bottom end of the upper tubing string is fixedly connected to the top end of the lower tubing string by a thread structure.

7. A completion method for a wellbore of an ultra-deep horizontal well according to claim 5, characterized in that, The thread structure includes a first thread group and a second thread group formed on the outer side of the bottom end of the upper tubing string, and a first thread groove group and a second thread groove group formed on the outer side of the top end of the lower tubing string. The first thread group and the second thread group are staggered in the height direction. The first thread groove group and the second thread groove group are staggered in the height direction. In the assembled state, the first thread group is snap - connected to the first thread groove group, and the second thread group is snap - connected to the second thread groove group.

8. The completion method for the wellbore of an ultra-deep horizontal well according to claim 7, characterized in that, Both the first thread group and the second thread group include a plurality of thread bars spaced apart in the height direction. The cross - sectional shape of each thread bar is trapezoidal. Both the first thread groove group and the second thread groove group include a plurality of thread grooves spaced apart in the height direction. The cross - sectional shape of each thread groove is trapezoidal.

9. The completion method of a wellbore of an ultra-deep horizontal well according to claim 7, characterized in that, The thread structure further includes a first inclined surface formed at the bottom end of the upper tubing and a second inclined surface formed at the top end of the lower tubing. In the assembled state, the first inclined surface abuts against the second inclined surface.

10. The completion method for a wellbore of an ultra-deep horizontal well according to claim 6 or 8, characterized in that, The thread structure further includes a first inclined surface formed at the bottom end of the upper tubing and a second inclined surface formed at the top end of the lower tubing. In the assembled state, the first inclined surface abuts against the second inclined surface.

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