A shallow surface casing leakage drilling device and a drilling method

Abstract

The invention discloses a shallow layer casing leakage drilling method, comprising a drill bit, a double female conversion joint, a drill pipe, a casing and a casing top fixing device; the casing is connected to the drill pipe respectively, the upper end of the drill pipe is connected to the top drive, and the lower end is connected to the double female conversion joint; the upper part of the casing is straightened by the top fixing device, and the lower end is fixed to the double female joint; the double female conversion joint connects the drill pipe, the casing and the drill bit, and is sealed with the well wall by a rubber part; during the drilling process, the drill string rotates to drive the drill bit to break the rock, the casing does not rotate and does not bear torque, the drilling fluid is pumped into the well through the annulus in the drill pipe, reaches the bottom of the well through the drill bit, and carries the rock cuttings back to the ground through the annulus between the drill pipe and the casing; the method can cope with the sudden shallow layer leakage during the oil drilling process, ensure that the rock cuttings are carried to the wellhead, avoid the complexity of the well, the operation site only needs to have the casing top fixing device and the double female conversion joint, no special customized casing is required, the method is simple to apply, and the operation preparation cycle is short.

Description

Technical Field

[0001] The present invention relates to a drilling device and a drilling method capable of dealing with the complexity of shallow surface formation well leakage in the field of oil drilling, in particular to a shallow surface casing penetration leakage drilling device and a shallow surface casing penetration leakage drilling method. Background Technique

[0002] During the oil drilling process, due to abnormally low formation pressure or the development of fractures and karsts, the phenomenon that drilling fluid or other media (such as cement slurry for well cementing) in the wellbore leak into the formation pores and fracture spaces is called well leakage.

[0003] Well leakage is one of the most serious complex situations affecting the safety of drilling operations. The occurrence of well leakage often brings inconvenience and losses to the drilling project, such as consuming the drilling cycle, losing drilling fluid and plugging materials, causing a series of new complex situations such as stuck pipe, blowout, and well collapse, and even leading to wellbore abandonment. Moreover, it will cause damage to the formation, resulting in significant economic losses. Well leakage has always been a major engineering and technical problem that plagues oil exploration and development at home and abroad and has not been completely solved yet. Research shows that well leakage problems account for more than 70% of the time and cost spent on dealing with complex situations in many oil fields in the world.

[0004] At present, the main plugging measures at home and abroad are mainly adjusted according to the leakage volume and leakage rate of well leakage. When there is a leakage situation (leakage rate < 5 m3 / h), a strong drilling operation with plugging while drilling is adopted, mainly adding plugging agents while drilling to the drilling fluid and adjusting the particle size ratio of the plugging agents according to the leakage degree; when the leakage rate reaches 5 - 15 m3 / h, static plugging is adopted, and a plugging slurry containing plugging agents while drilling and composite plugging agents is prepared; when the leakage rate reaches 15 - 30 m3 / h, static bridge slurry plugging is adopted, preparing a thick plugging slurry and adding bamboo fibers, composite plugging agents, chemical consolidants, etc.; when the leakage rate > 30 m3 / h or lost circulation occurs, mainly cement injection plugging is adopted. This plugging scheme has a certain effect when dealing with medium-depth and deep formations.

[0005] However, in the shallow surface formation, due to the poor formation compaction effect, there are easily fractures and karsts developed. When well leakage occurs, it often quickly develops into lost circulation. Therefore, the technical difficulties of shallow surface plugging are reflected in: ① For lost circulation caused by large fractures and karsts, bridging plugging materials cannot accumulate and bridge in the leakage channels to form an effective blockage; ② Most of the leakage formations in the shallow surface are groundwater layers. During the process of cement injection plugging, the formation water is replaced with cement, and the cement cannot stay in the fractures. At the same time, the cement is severely diluted by water, often resulting in no cement plug or a poor cement plug cementation quality, and the cement plug plugging technology has a poor effect; ③ When the method of rapid drilling with clear water is adopted, some wells show the phenomenon of water leakage but no sand leakage, and there is a lot of sediment accumulation in the wellbore, and the stuck pipe phenomenon is frequent; ④ The methods of plugging slurry and cement injection will seriously pollute the underground water layer. Affected by environmental protection, there are very few shallow surface plugging methods.

[0006] In some areas, the casing drilling process has been attempted to penetrate the lost circulation zone. This process requires the casing to bear the torque itself, and special processing of the casing connection type is needed. Moreover, the circulation space of this process is still the annulus between the casing and the wellbore. In the case of lost circulation in the annulus, the problem of carrying cuttings still cannot be solved, and the risk of casing sticking is high.

[0007] In recent years, the process of air-lifting through lost circulation with double-wall drill pipes has been developed. Its principle is to utilize the double annulus space existing in the double-wall drill pipes. One inner annulus injects drilling fluid, and the other inner annulus injects air. After the two-phase flow is mixed, a low-density fluid is formed and returns to the wellhead through the outer annulus.

[0008] This process significantly reduces the density of the drilling fluid passing through the lost circulation zone in the outer annulus, which can effectively reduce the lost circulation volume in fractures. However, its effect on lost circulation in solution cavities is limited. In addition, the processing accuracy of double-wall drill pipes is high, the cost of air-inflating equipment is high, and when sudden lost circulation occurs, the operation preparation period is long. Summary of the Invention

[0009] The purpose of the present invention is to provide a shallow surface casing penetration drilling device and drilling method in view of the deficiencies in the prior art.

[0010] The technical solution is as follows:

[0011] A shallow surface casing penetration drilling method includes a drill bit, a double-male adapter, drill pipes, a casing, and a casing top fixing device.

[0012] The casing and the drill pipes are connected respectively. The upper end of the drill pipe is connected to the top drive, and the lower end is connected to the double-male adapter; the upper part of the casing is straightened by the top fixing device, and the lower end is fixed to the double-male joint; the double-male adapter connects the drill pipe, the casing, and the drill bit, and is sealed with the wellbore by rubber parts.

[0013] The upper end of the double-male adapter is connected to the drill pipe, and the lower end is connected to the drill bit. The relative rotation between the double-male adapter and the casing string is realized by a rolling bearing.

[0014] The double-male adapter is connected to the bottom end of the casing through threads around its circumference; rubber parts are installed on the periphery to seal the gap between the casing and the wellbore.

[0015] The casing top fixing device consists of a central collar and four connecting rods. The central outer collar fixes the casing, and the connecting rods are fixed to the drilling rig foundation.

[0016] The central collar of the casing top fixing device consists of a central outer collar and a central inner collar. The central outer collar is a circular steel ring connected to a support rod. The central inner collar consists of four 1 / 4 circular rings, which are connected to the central outer collar by springs on the outside and are equipped with rollers on the inside to ensure the smooth passing of the casing string coupling.

[0017] During the drilling process, the drill string rotates to drive the drill bit to break rock. The casing does not rotate and does not bear torque. The drilling fluid is pumped into the wellbore through the inner annulus of the drill pipe, reaches the bottom of the well through the drill bit, carries the cuttings and returns to the surface through the annulus between the drill pipe and the casing. This method can handle sudden shallow surface losses during oil drilling, ensure that the cuttings are carried to the wellhead, avoid downhole complications, and only requires the on-site standby of a casing top fixing device and a double-mother adapter. There is no need to specially customize the casing. This method is simple to apply and has a short operation preparation cycle.

[0018] The beneficial effects of the present invention are:

[0019] During the drilling process, the drill string rotates to drive the drill bit to break rock. The casing does not rotate and does not bear torque. The drilling fluid is pumped into the wellbore through the inner annulus of the drill pipe, reaches the bottom of the well through the drill bit, carries the cuttings and returns to the surface through the annulus between the drill pipe and the casing. This method can handle sudden shallow surface losses during oil drilling, ensure that the cuttings are carried to the wellhead, avoid downhole complications, and only requires the on-site standby of a casing top fixing device and a double-mother adapter. There is no need to specially customize the casing. This method is simple to apply and has a short operation preparation cycle.

[0020] It can effectively handle sudden shallow surface losses during oil drilling, ensure that the cuttings are carried to the wellhead, avoid downhole complications, and only requires the on-site standby of a casing top fixing device and a double-mother adapter. There is no need to specially customize the casing. This method is simple to apply and has a short operation preparation cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of a shallow surface casing penetration and leakage drilling method.

[0022] Figure 2 It is the front view of the casing top fixing device.

[0023] Figure 3 It is the top view of the casing top fixing device.

[0024] Figure 4 It is the front view of the double-mother adapter.

[0025] Figure 5 It is the top view of the double-mother adapter.

[0026] Figure 6 It is a schematic diagram of making a connection during a shallow surface casing penetration and leakage drilling method.

[0027] Markings in the figure: 1. Drill pipe string, 2. Casing string, 3. Drill bit, 4. Double-male adapter, 5. Casing top fixing device, 6. Derrick foundation, 7. Drilling fluid, 8. Formation, 9. Lost circulation zone, 10. Central outer ring sleeve, 11. Central inner ring sleeve, 12. Spring, 13. Rubber roller, 14. Connecting rod, 15. Telescopic adjusting rod, 16. Fixed hook, 17. Joint body, 18. Top thread, 19. Adapter central hole, 20. Bottom thread, 21. Rolling bearing, 22. Support connecting rod, 23. Bracket body, 24. Inner thread of annular bracket, 25. Annular rubber sealing ring, 26. Drilling rig platform, 27. Drilling top drive device, 28. Single drill pipe, 29. Drill pipe collar, 30. Single casing. Detailed implementation mode

[0028] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with the specific implementation modes and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0029] Refer to the attached Figure 1 , the structural composition of the shallow surface casing penetration drilling device: includes a drill bit 4, a double-male adapter 4, a drill pipe string 1, a casing string 2, and a casing top fixing device 5.

[0030] Refer to the attached Figure 2 , attached Figure 3 , the structural composition of the casing top fixing device: the casing top fixing device 5 is composed of a central ring sleeve and a connecting rod 14. The central ring sleeve fixes the casing string 2, and the connecting rod 14 is fixed to the derrick foundation 6. The central ring sleeve is composed of a central outer ring sleeve 10 and a central inner ring sleeve 11. The central outer ring sleeve 10 is a circular steel ring connected to the connecting rod 14. The central inner ring sleeve 11 is composed of four 1 / 4 circular rings, the outer side of which is connected to the central outer ring sleeve 10 through a spring 12, and the inner side is provided with a rubber roller 13. The support rod is composed of a connecting rod 14, a telescopic adjusting rod 15, and a fixed hook 16.

[0031] Refer to the attached Figure 4 , attached Figure 5, Structure Composition of the Double-Male Adapter 4: The double-male adapter 4 includes an adapter body 17, a top thread 18, a bottom thread 20, a sliding bearing 21, a support connecting rod 22, and an annular bracket assembly. The annular bracket assembly includes a bracket body, an internal thread 24 of the bracket, and an annular rubber sealing ring 25. The top thread 18 of the double-male adapter 4 is connected to the drill pipe string 1, and the bottom thread 20 is connected to the drill bit 3. The bracket body 23 is connected to the bottom end of the casing string 2 through the internal thread 24 of the annular bracket. The support connecting rod 22 connects the rolling bearing 21 and the bracket body 23, and the bracket body 23 is connected to the adapter body 17 through the rolling bearing 21 to realize the relative rotation between the adapter body 17 and the casing string 2. An annular rubber sealing ring 25 is installed on the periphery of the bracket body 23 to seal the gap between the casing string 2 and the wellbore wall.

[0032] Working Process:

[0033] The drill pipe string 1 drives the drill bit 3 to rotate and break the rock of the formation 8. The drilling fluid 7 is pumped into the bottom of the well through the drill pipe string 1, the double-male adapter 4, and the drill bit 3, and carries the cuttings back to the surface through the annulus between the drill pipe string 1 and the casing string 2. It avoids the drilling fluid 7 and the cuttings from returning to the leakage layer 9 through the outer annulus between the casing string 2 and the formation 8.

[0034] Surface Part: The upper end of the casing string 2 is fixed by the casing top fixing device 5, and the lower end is fixed by the double-male adapter 4. During the drilling process, the drill pipe string 1, the adapter body 17, and the drill bit 3 rotate at the same speed, and the casing top fixing device 5, the casing string 2, and the accessories of the double-male adapter 4 do not rotate. The body of the casing string 2 does not bear torque, and there is no need for special treatment of the coupling type, reducing the safety of the downhole casing.

[0035] Four connecting rods 14 are connected to the derrick foundation 6 through fixed hooks 16 to fix the entire casing top fixing device 5. By adjusting the telescopic adjusting rod 15, the centering degree of the central outer ring sleeve 10 and the casing string 2 is ensured. When the casing string 2 shakes greatly, the central inner ring sleeve 11 and the spring 12 can play a certain buffering role. When the coupling of the casing string 2 passes through this device, the spring 12 contracts and the diameter of the central inner ring sleeve 11 expands to ensure the smooth passage of the coupling of the casing string 2. During the downward passage of the casing string 2, the rubber rollers 13 are used to reduce the frictional resistance between the casing top fixing device 5 and the casing string 2 to ensure the smooth passage of the casing string 2.

[0036] Downhole Part: During the drilling process, the adapter body 17 rotates together with the drill pipe string 1 and the drill bit 3, and the rolling bearing 21 maintains the relative rotation between the bracket body 23 and the adapter body 17. The bracket body 23 is connected to the casing string 2 to support the casing string 2 stably and keep it horizontally stationary together with the casing string 2. The annular rubber sealing ring 25 on the periphery of the bracket body 23 maintains the sealing state between the casing string 2 and the formation 8 to ensure that the drilling fluid 7 returns to the wellhead through the inner annulus between the drill pipe string 1 and the casing string 2.

[0037] A shallow surface casing penetration drilling method based on a shallow surface casing penetration drilling device of the present invention:

[0038] The drill string 1 drives the drill bit 3 to rotate and break the rock of the formation 8. The drilling fluid 7 is pumped into the bottom of the well through the drill string 1, the double-mother adapter 4 and the drill bit 3, and carries the cuttings back to the surface through the annulus between the drill string 1 and the casing string 2. It avoids the drilling fluid 7 and the cuttings from returning to the surface through the outer annulus between the casing string 2 and the formation 8 and entering the leakage layer 9.

[0039] Refer to the appendix Figure 6 , and the implementation scheme of drilling for single joints of the present invention will be described in detail.

[0040] Due to the difference in the lengths of the drill pipe single joint 28 and the casing single joint 30, a single-joint operation needs to be carried out every time the drill reaches the collar of a drill pipe or a casing. When connecting the drill pipe single joint 28, the top drive 27 lifts the drill string 1 and the casing string 2 to the drill pipe collar 29, disconnects the drill pipe collar 29 and connects the drill pipe single joint 28. After tightening, the drill string is lowered and drilling is resumed; when connecting the casing single joint 30, the top drive 27 lifts the drill string 1 and the casing string 2 to the drill pipe collar 29, disconnects the drill pipe collar 29 and connects the casing single joint 30. First, tighten the drill pipe single joint 28, then lift the drill string to the casing single joint collar and tighten the casing single joint, and resume drilling.

[0041] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A drilling method for a shallow surface casing penetration drilling device, the shallow surface casing penetration drilling device comprising a drill pipe string (1), a drill bit (3), and a casing string (2), characterized in that: The casing string (2) is rotatably mounted on the derrick foundation (6) through the casing top fixing device (5); the casing top fixing device (5) consists of a central collar and support rods. The central collar is rotatably sleeved on the casing string (2), and the support rods are fixedly connected between the derrick foundation (6) and the central collar; the central collar consists of a central outer collar (10) and a central inner collar (11). The central outer collar (10) is a circular steel ring, externally fixedly connected to the connecting rod (14). The central inner collar (11) is composed of four 1 / 4 circular rings, externally connected to the central outer collar (10) through a spring (12), and internally provided with rubber rollers (13); the support rods are sequentially connected by a connecting rod (14), a telescopic adjusting rod (15), and a fixed hook (16); also included is a double-male adapter (4): the double-male adapter (4) includes an adapter body (17), a rolling bearing (21), a support connecting rod (22), and an annular bracket assembly; the adapter body (17) is rotatably connected to the casing string (2) through the annular bracket assembly; both ends of the adapter body (17) are respectively provided with a top thread (18) and a bottom thread (20). The top thread (18) is connected to the drill pipe string (1), and the bottom thread (20) is connected to the drill bit (3); one end of the support connecting rod (22) is fixedly connected to the rolling bearing (21), and the other end is fixedly connected to the annular bracket assembly; the annular bracket assembly includes a bracket body (23) and a bracket internal thread (24); the bracket internal thread (24) is connected to the bottom end of the casing string (2). The support connecting rod (22) connects the rolling bearing (21) and the bracket body (23), and the bracket body (23) is connected to the adapter body (17) through the rolling bearing (21) to realize the relative rotation of the adapter body (17) and the casing string (2); an annular rubber sealing ring (25) is installed on the periphery of the bracket body (23) to seal the gap between the casing string (2) and the wellbore wall; the drill pipe string (1) drives the drill bit (3) to rotate and break the rock of the formation (8); the drilling fluid (7) is pumped into the bottom of the well through the drill pipe string (1), the double-male adapter (4), and the drill bit (3), and carries the cuttings back to the surface through the annulus between the drill pipe string (1) and the casing string (2); it avoids the drilling fluid (7) and the cuttings from returning to the lost circulation zone (9) through the outer annulus between the casing string (2) and the formation (8); surface part: the upper end of the casing string (2) is fixed by the casing top fixing device (5), and the lower end is fixed by the double-male adapter (4); during the drilling process, the drill pipe string (1), the adapter body (17), and the drill bit (3) rotate at the same speed, and the accessories of the casing top fixing device (5), the casing string (2), and the double-male adapter (4) do not rotate; the casing string (2) body does not bear torque, and there is no need for special treatment of the coupling type, reducing the safety of the downhole casing; the four connecting rods (14) are connected to the derrick foundation (6) through the fixed hooks (16) to fix the entire casing top fixing device (5);By adjusting the telescopic adjusting rod (15), the centering of the central outer ring sleeve (10) with the casing string (2) is ensured. When the casing string (2) shakes, the central inner ring sleeve (11) and the spring (12) play a certain buffering role; when the coupling of the casing string (2) passes through this top fixing device, the spring (12) contracts and the diameter of the central inner ring sleeve (11) expands to ensure the smooth passage of the coupling of the casing string (2); during the downward passage of the casing string (2), the rubber rollers (13) are used to reduce the frictional resistance between the top fixing device of the casing (5) and the casing string (2) to ensure the smooth passage of the casing string (2); downhole part: during the drilling process, the joint body (17) rotates together with the drill pipe string (1) and the drill bit (3), and the rolling bearing (21) maintains the relative rotation between the bracket body (23) and the joint body (17); the bracket body (23) is connected to the casing string (2) to support the stable casing string (2) and keep it horizontally stationary together with the casing string (2); the annular rubber sealing ring (25) on the periphery of the bracket body (23) maintains the sealing state between the casing string (2) and the formation (8) to ensure that the drilling fluid (7) returns to the wellhead through the inner annulus between the drill pipe string (1) and the casing string (2).; 2. The drilling method of a shallow surface casing penetration drilling device according to claim 1, characterized in that It also includes a method for connecting drill pipes: Since there are differences in the lengths of drill pipe stands (28) and casing stands (30), a connection operation of drill pipe stands needs to be performed each time the drill reaches the coupling of a drill pipe or a casing; when connecting a drill pipe stand (28), the top drive (27) lifts the drill pipe string (1) and the casing string (2) to the drill pipe coupling (29), uncouples the drill pipe coupling (29) and connects the drill pipe stand (28), tightens the connection after which the drill string is lowered, and drilling resumes; when connecting a casing stand (30), the top drive (27) lifts the drill pipe string (1) and the casing string (2) to the drill pipe coupling (29), uncouples the drill pipe coupling (29) and connects the casing stand (30), first tightens the drill pipe stand (28), then lifts the drill string to the coupling of the casing stand and tightens the casing stand, and drilling resumes.

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