A mill tool and method for large section, curved deformation fracture casing repair

Abstract

The present application belongs to the technical field of oil production workover, and particularly relates to a milling tool and method for repairing a large-section curved and deformed and broken casing. The milling tool for repairing a large-section curved and deformed and broken casing comprises, from bottom to top, a lead cone probe, a milling working part, a weighted drill pipe, a hydraulic pressurizer and a drill pipe connected in sequence. The milling working part comprises, from bottom to top, a plurality of conical milling columns and a millable conical drill pipe sub connected in sequence. The hydraulic pressurizer is used to apply pressure to drive the lead cone probe to guide the milling working part to move downward in the casing, and mill and punch through the curved and deformed and broken casing channel. The present application enhances the flexibility of the tool by changing the existing compound milling cone into a conical milling column, reduces the contact surface between the milling tool and the casing, and bends along the bending direction of the casing, thereby avoiding milling and breaking the casing. Meanwhile, the tool has the function of reverse cutting and eyeing, and can perform a stuck drill pipe treatment during the milling process.

Description

Technical Field

[0001] This invention belongs to the field of oil well workover technology, and specifically relates to a milling tool and method for repairing long-section bent and deformed casing. Background Technology

[0002] Casing is widely used to fix the wellbore of oil, gas, and water wells or to isolate formation fluids to prevent wellbore collapse, ensure well safety, and facilitate drilling and resource extraction. However, due to factors such as engineering construction, environmental corrosion, fault activity, and changes in geostress, downhole casing often suffers damage such as rupture, deformation, perforation, and breakage. This results in a smaller casing diameter, preventing large-diameter tools from passing through and thus affecting production.

[0003] The expansion casing drill string structure consists of: expansion tool + centralizer + 4-stage drill collar + centralizer + drill pipe. The milling drill string structure consists of: milling taper (milling shoe) + retrieval cup + centralizer + 4-stage drill collar + centralizer + retrieval cup + drill pipe. Because the curved sections of the casing are generally several meters to tens of meters long, and both diameter reduction and fractures exist simultaneously, with large curvature and small radius, the rigidity of the support structure drill string during expansion casing cannot pass through, making it impossible to open the narrowed diameter passage. During milling shoe, the rigidity of the support structure drill string results in no progress; the milling shoe or milling taper grinds through the curved casing wall, preventing advancement along the curved casing and instead creating a vertical opening, causing a downhole accident where the drill string exits the casing; or during milling shoe, the drill string cannot bend at the damaged area of ​​the casing and directly creates a opening through the fracture, causing a downhole accident where the drill string exits the casing, leading to project failure. Furthermore, during milling and casing repair, the grinding shoe or milling tap often gets stuck due to the broken casing. Since the grinding shoes or milling taps currently used do not have the function of reverse cutting and reaming, once a stuck drill bit occurs, the only option is to cut and retrieve the milling and grinding tools, causing secondary and complex downhole accidents, and potentially leading to the abandonment of the oil or water well. Based on the current technology, wells with large sections of bent, deformed, and fractured casing damage are basically impossible to repair successfully, and can only maintain the current production status or be shut down and abandoned. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide a milling tool and method for repairing large-section bent and deformed sleeves. This invention has a simple structure, replacing the existing compound milling cone with a conical milling column, which enhances the tool's flexibility, reduces the contact area between the milling tool and the sleeve, and allows the tool to bend in the direction of the sleeve's bending, thus avoiding damage to the sleeve. At the same time, it has the function of reverse cutting and shaving, which can be used to handle stuck drills during the milling process.

[0005] The technical solution of this invention is as follows: a milling tool for repairing a long section of bent and deformed casing, comprising, from bottom to top, a guide cone probe, a milling working part, a weighted drill rod, a hydraulic pressure device, and a drill rod connected in sequence. The milling working part comprises, from bottom to top, several conical milling columns and millable conical drill rod short sections connected in sequence. The conical milling column at the lower end of the milling working part is fixedly connected to the upper part of the guide cone probe, and the millable conical drill rod short section at the upper end of the milling working part is fixedly connected to the weighted drill rod. In use, the milling tool is placed inside the casing, and the hydraulic pressure device is used to apply pressure, driving the guide cone probe to guide the milling working part to move downward inside the casing, thus milling and opening up the channel of the bent and deformed casing.

[0006] The guide cone probe is a probe type with a hollow interior. It includes a fixedly connected upper guide cone connector and a guide rod probe. The outer diameter of the upper guide cone connector is greater than the outer diameter of the guide rod probe. A milled alloy strip is provided at the diameter change point where the upper guide cone connector and the guide rod probe are connected. The lower end face of the guide rod probe is an inclined end face, and a probe alloy strip is provided on the inclined end face.

[0007] The pilot cone probe is stepped and hollow inside. It includes a probe upper connector, a probe body, and a probe head that are fixedly connected. The probe upper connector has a drain plug in the middle and a diameter retainer at the lower end. The upper part of the probe body has a first-level step and a second-level step in sequence. The outer diameter of the diameter retainer is greater than the outer diameter of the second-level step, which is greater than the outer diameter of the first-level step. The probe head is conical and has a drain hole on it. The drain hole is connected to the hollow interior of the pilot cone probe.

[0008] The probe rod is 700mm long and has an outer diameter of 60mm.

[0009] The conical milling column is hollow inside and includes an upper milling column connector, a milling column body, and a lower milling column connector connected in sequence. The outside of the milling column body is provided with a conical alloy, which includes an upper conical surface and a lower conical surface. The bottom surfaces of the upper and lower conical surfaces coincide, and the cone height of the upper conical surface is less than the cone height of the lower conical surface.

[0010] The length of the tapered milling column is 500mm, and the outer diameter range of the tapered milling column is: 85~95mm, 95~105mm, 105~110mm, 110~115mm.

[0011] The conical milling column and the millable conical drill rod short section are connected by a rotatable universal joint. The rotatable universal joint is hollow inside and includes a movable joint upper connector, a movable short section, and a movable joint lower connector connected in sequence. The upper part of the movable short section is fixedly connected to the movable joint upper connector, and the lower part of the movable short section is provided with a spherical key. A locking housing is provided on the outside of the spherical key, and the movable joint lower connector is fixedly connected to the locking housing.

[0012] The millable tapered drill pipe section is hollow inside and includes an upper joint, a body, and a lower joint connected in sequence. The outer diameters of the upper and lower joints are the same and larger than the outer diameter of the body. The upper joint is provided with a milled alloy strip at the diameter change point between the upper and lower joints, and the lower joint is provided with a milled alloy strip at the diameter change point between the lower and lower joints.

[0013] The lengths of the millable tapered drill pipe sections are 500mm, 1000mm, and 1500mm.

[0014] The weighted drill rod is an 18° inclined weighted drill rod.

[0015] A method for repairing a ruptured casing with a large section of bending deformation, using any of the milling tools described above for repairing ruptured casings with a large section of bending deformation, includes the following steps:

[0016] S1: Detection of sleeve damage;

[0017] First, use logging instruments to check the casing damage. Then, lower a conical lead mold 10mm smaller than the inner diameter of the casing into the well to check the casing's reduced diameter, cracking degree, and depth. If the conical lead mold cannot pass through the casing, replace it with a smaller lead mold, reducing the size by 3-4mm each time.

[0018] S2: Casing clearance inspection;

[0019] Use Φ60.3mm or Φ73mm tubing to check the casing diameter and insert a flexible well gauge with a wall thickness of 3mm*3~5m to check the casing bending degree. The diameter of the well gauge should be 10mm smaller than the inner diameter of the casing. If it cannot pass, replace it with a smaller well gauge, reducing the size by 3~4mm each time.

[0020] S3: Based on the casing damage status in step S1, determine the number of tapered milling columns and millable tapered drill rod short sections in the milling working section. Based on the casing passage status in step S2, determine the type of pilot cone probe. The specific determination method is as follows:

[0021] Based on the casing damage length L in step S1, if L≤10m, the milling working section uses one conical milling column and one millable conical drill pipe short section; if 10m<L≤20m, the milling working section uses two conical milling columns and two millable conical drill pipe short sections, and so on, to determine the number of conical milling columns and millable conical drill pipe short sections in the milling working section; based on the maximum diameter D of the casing well gauge in step S2, if D>60mm, the guide cone probe is selected as a probe type; if D≤60mm, the guide cone probe is selected as a stepped type.

[0022] S4: Assemble and lower the milling tool for repairing large-section bent and deformed casing. The hydraulic pressure device applies pressure, which drives the guide cone probe to guide the milling working part to move downward inside the casing. The milling opens up the channel of the bent and deformed casing, thus realizing the casing repair.

[0023] The technical advantages of this invention are as follows:

[0024] 1. The present invention provides a guide cone probe at the bottom of the tool to guide the milling working part to move downward within the sleeve, ensuring that the tool accurately enters the sleeve to be repaired. At the same time, the guide cone probe is equipped with a milling alloy strip and a probe alloy strip, which can also play a cutting role during the milling rotation process.

[0025] 2. This invention replaces the existing compound milling cone with a conical milling column, which enhances the tool's flexibility, reduces the contact area between the milling tool and the sleeve, and allows for milling with large diameter and short length without strain. The tool can bend in the direction of the sleeve's bending, avoiding damage to the sleeve. The outside of the milling column body is provided with a conical alloy, which includes an upper conical surface and a lower conical surface. The upper conical surface plays a role in reverse cutting and shaving.

[0026] 3. This invention connects the tapered milling column and the millable tapered drill rod short section by a rotating universal movable elbow, which can transmit torque and play a rotational role. It can also tilt in all directions at 5~7°, ensuring that the tool can bend and can move along the trajectory of the curved casing, thus solving the problem that existing strong-supported drill tools cannot bend.

[0027] 4. The present invention uses a millable tapered drill rod short section to adjust the bending radius of the drill bit. It is equipped with an upper joint milling alloy strip and a lower joint milling alloy strip, which play a role in back-grinding and milling cutting during the lifting of the drill bit.

[0028] 5. This invention replaces the weight of the drill collar with a hydraulic pressurizer, changing the tool pressurization method and transforming mechanical pressurization into hydraulic pressurization to provide stable drilling pressure for the tool, thus realizing flexible pressurized drilling.

[0029] 6. This invention addresses the repair of large sections of bent and deformed casing, avoiding downhole accidents such as window opening and abandonment during existing casing repair processes, thus improving the success rate of casing-damaged well repair. The overall success rate of casing-damaged well repair reaches 80%.

[0030] The following will provide further explanation in conjunction with the accompanying drawings. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a milling tool structure for repairing a long-section bent and deformed sleeve according to an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of a probe-type derrick probe according to an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the stepped guide cone probe according to an embodiment of the present invention.

[0034] Figure 4 This is a schematic diagram of the structure of the conical milling column according to an embodiment of the present invention.

[0035] Figure 5 This is a schematic diagram of the rotatable universal joint according to an embodiment of the present invention.

[0036] Figure 6 This is a schematic diagram of the structure of a millable tapered drill pipe section according to an embodiment of the present invention.

[0037] Figure 7 This is a schematic diagram of the milling tool structure for casing repair in well XX according to an embodiment of the present invention.

[0038] Reference numerals: 1-Draw-out cone probe, 2-Conical milling column, 3-Rotary universal joint, 4-Millable conical drill pipe short section, 5-Weighted drill pipe, 6-Hydraulic pressure booster, 7-Drill pipe, 8-Casing, 11-Draw-out cone upper connector, 12-Milling alloy strip, 13-Draw-out rod probe, 14-Probe alloy strip, 21-Milling column upper connector, 22-Milling column body, 23-Conical alloy, 24-Milling column lower connector, 31-Millable elbow lower connector, 32- 33-Moving elbow upper connector, 34-Spherical key, 35-Locking housing, 41-Drill pipe short section upper connector, 42-Upper connector milled alloy strip, 43-Drill pipe short section body, 44-Lower connector milled alloy strip, 45-Drill pipe short section lower connector, 111-Probe upper connector, 112-Drain plug, 113-Gauge retainer, 114-Secondary step, 115-First stage step, 116-Probe body, 117-Drain hole, 118-Probe head. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0040] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0041] Example 1

[0042] like Figure 1 As shown, a milling tool for repairing large-segment bent and deformed casing includes, from bottom to top, a guide cone probe 1, a milling working part, a weighted drill rod 5, a hydraulic pressure device 6, and a drill rod 7 connected in sequence. The milling working part includes, from bottom to top, several conical milling columns 2 and millable conical drill rod short sections 4 connected in sequence and rotatably. The conical milling columns 2 at the lower end of the milling working part are fixedly connected to the upper part of the guide cone probe 1, and the millable conical drill rod short sections 4 at the upper end of the milling working part are fixedly connected to the weighted drill rod 5. In use, the milling tool is placed inside the casing, and the hydraulic pressure device 6 is used to apply pressure, driving the guide cone probe 1 to guide the milling working part to move downward inside the casing 8, milling open the channel of the bent and deformed casing 8.

[0043] In practical use, this invention replaces the weight of the drill collar with a hydraulic pressurizer 6, changing the tool pressurization method and transforming mechanical pressurization into hydraulic pressurization to provide stable drilling pressure for the tool, thus achieving flexible pressurized drilling. The hydraulic pressurizer is existing technology. The hydraulic pressurizer 6 is used to apply pressure, driving the guide cone probe 1 to guide the milling working part to move downward within the casing 8. The milling opens up the channel of the bent and deformed casing 8. This invention changes the existing compound milling cone to a conical milling column, enhancing tool flexibility, reducing the contact area between the milling tool and the casing, and allowing the tool to bend in the direction of casing bending, avoiding damage to the casing.

[0044] like Figure 2 As shown, preferably, the guide cone probe 1 is a probe type with a hollow interior, including a guide cone upper connector 11 and a guide rod probe 13 that are fixedly connected. The outer diameter of the guide cone upper connector 11 is greater than the outer diameter of the guide rod probe 13. A milled alloy strip 12 is provided at the diameter change point where the guide cone upper connector 11 and the guide rod probe 13 are connected. The lower end face of the guide rod probe 13 is an inclined end face, and a probe alloy strip 14 is provided on the inclined end face.

[0045] In actual use, the guide cone probe 1 of the present invention is a probe type with a hollow interior. During the repair of the sleeve 8, liquid flows out from the hollow interior of the guide cone probe 1 to wash away the milling debris and prevent the drill from getting stuck. By setting the guide cone probe 1 at the bottom of the tool, the milling working part is guided to move downward in the sleeve 8, ensuring that the tool accurately enters the sleeve 8 to be repaired. At the same time, the guide cone probe 1 is equipped with a milling alloy strip 12 and a probe alloy strip 14, which can also play a cutting role during the milling rotation.

[0046] More preferably, the lead rod probe 13 has a length of 700 mm and an outer diameter of 60 mm.

[0047] In actual use, the length of the probe 13 of this invention is 700mm, which can ensure that the tool accurately enters the sleeve 8 to be repaired.

[0048] like Figure 3 As shown, preferably, the pilot cone probe 1 is stepped and hollow inside, including a probe upper connector 111, a probe body 116, and a probe head 118 that are fixedly connected. The probe upper connector 111 is provided with a drain plug 112 in the middle and a diameter retainer 113 at the lower end of the probe upper connector 111. The upper part of the probe body 116 is provided with a first-stage step 115 and a second-stage step 114 in sequence. The outer diameter of the diameter retainer 113 is greater than the outer diameter of the second-stage step 114, which is greater than the outer diameter of the first-stage step 115. The probe head 118 is conical and is provided with a drain hole 117, which is connected to the hollow interior of the pilot cone probe 1.

[0049] In actual use, the present invention guides the milling working part to move downward in the sleeve 8 through the conical probe head 118. The milling and expansion is carried out step by step through the first step 115, the second step 114, and the diameter protection 113 to ensure that the tool accurately enters the sleeve 8 to be repaired. The drain hole 117 is used for the liquid inside the conical probe 1 to flow out. If a blockage is encountered, the probe body 116 pressurizes and opens the drain plug 112 to discharge the liquid inside the conical probe 1.

[0050] like Figure 4 As shown, preferably, the conical milling column 2 is hollow inside and includes a milling column upper connector 21, a milling column body 22, and a milling column lower connector 24 connected in sequence. The outside of the milling column body 22 is provided with a conical alloy 23, which includes an upper conical surface and a lower conical surface. The bottom surfaces of the upper conical surface and the lower conical surface coincide, and the cone height of the upper conical surface is less than the cone height of the lower conical surface.

[0051] In practical use, this invention replaces the existing compound milling cone with a conical milling column 2, which enhances the tool's flexibility, reduces the contact area between the milling tool and the sleeve, and allows for milling with large diameter and short length without strain. The tool can bend in the direction of the sleeve's bending, avoiding damage to the sleeve. The outside of the milling column body 22 is provided with a conical alloy 23, which includes an upper conical surface and a lower conical surface. The upper conical surface serves to perform reverse cutting and shaving.

[0052] More preferably, the length of the conical milling column 2 is 500mm, and the outer diameter range of the conical milling column 2 is: 85~95mm, 95~105mm, 105~110mm, 110~115mm.

[0053] In actual use, the outer diameter of the conical milling column 2 described in this invention is in the range of 85~95mm, 95~105mm, 105~110mm, and 110~115mm. The size and quantity of the conical milling column 2 can be selected and matched according to the actual sleeve damage situation.

[0054] like Figure 5 As shown, preferably, the conical milling column 2 and the millable conical drill rod short section 4 are connected by a rotatable universal joint 3. The rotatable universal joint 3 is hollow inside and includes a movable joint upper connector 33, a movable short section 32, and a movable joint lower connector 31 connected in sequence. The upper part of the movable short section 32 is fixedly connected to the movable joint upper connector 33. The lower part of the movable short section 32 is provided with a ball key 34. A locking housing 35 is provided on the outside of the ball key 34. The movable joint lower connector 31 is fixedly connected to the locking housing 35.

[0055] In practical use, this invention connects the conical milling column 2 and the millable conical drill rod short section 4 via a rotatable universal joint 3. The rotatable universal joint 3 is hollow inside and includes a movable joint upper connector 33, a movable short section 32, and a movable joint lower connector 31 connected in sequence. The upper part of the movable short section 32 is fixedly connected to the movable joint upper connector 33, and the lower part of the movable short section 32 is provided with a spherical key 34. A locking housing 35 is provided on the outside of the spherical key 34. The movable joint lower connector 31 is connected to the locking housing 35. 5. Fixed connection: The movable short section 32 and the movable elbow lower connector 31 are movably connected by a ball key 34. The ball key 34 can drive the movable short section 32 to tilt in all directions at 5~7° within the spherical cavity on the locking housing 35. At the same time, the movable short section 32 can transmit torque through the ball key 34, the locking housing 35, and the movable elbow lower connector 31, thus achieving a rotational function. This ensures that the tool can bend and can advance along the trajectory of the curved casing, solving the problem that existing strong-supported drilling tools cannot bend.

[0056] like Figure 6As shown, preferably, the millable tapered drill pipe section 4 is hollow inside and includes an upper drill pipe section connector 41, a drill pipe section body 43, and a lower drill pipe section connector 45 connected in sequence. The outer diameters of the upper drill pipe section connector 41 and the lower drill pipe section connector 45 are the same and larger than the outer diameter of the drill pipe section body 43. An upper connector milling alloy strip 42 is provided at the diameter change point connecting the upper drill pipe section connector 41 and the drill pipe section body 43, and a lower connector milling alloy strip 44 is provided at the diameter change point connecting the lower drill pipe section connector 45 and the drill pipe section body 43.

[0057] In actual use, the present invention can adjust the bending radius of the drill bit through the millable tapered drill rod short section 4. It is equipped with an upper joint milling alloy strip 42 and a lower joint milling alloy strip 45, which play the role of back-grinding milling and cutting during the lifting of the drill bit.

[0058] More preferably, the length of the millable tapered drill rod section 4 is 500mm, 1000mm, or 1500mm.

[0059] In actual use, the present invention can select and match the length and quantity of the millable tapered drill pipe short section 4 according to the actual casing damage situation.

[0060] Preferably, the weighted drill rod 5 is an 18° inclined weighted drill rod.

[0061] In actual use, the weighted drill pipe 5 of the present invention is an 18° inclined weighted drill pipe. During the process of the tool being lowered into and pulled out of the wellbore, the 18° inclined weighted drill pipe can reduce the frictional resistance between the drill pipe joint and the casing, and prevent the drill from getting stuck.

[0062] Example 2

[0063] A method for repairing a ruptured casing with a large section of bending deformation, using any of the milling tools described above for repairing ruptured casings with a large section of bending deformation, includes the following steps:

[0064] S1: Damage inspection of sleeve 8;

[0065] First, use logging instruments to check the damage to casing 8. Then, lower a conical lead mold 10mm smaller than the inner diameter of casing 8 into the well to check the diameter reduction, cracking degree and depth of casing 8. If the conical lead mold cannot pass through casing 8, replace it with a smaller lead mold, reducing the size by 3-4mm each time.

[0066] S2: Sleeve 8 pass inspection;

[0067] Use Φ60.3mm or Φ73mm tubing to check the passage of casing 8 through the duct, and lower a flexible well gauge with a wall thickness of 3mm*3~5m to check the degree of bending of casing 8. The diameter of the well gauge should be 10mm smaller than the inner diameter of casing 8. If it cannot pass through, replace it with a smaller well gauge, reducing the size by 3~4mm each time.

[0068] S3: Based on the damage status of the casing 8 in step S1, determine the number of tapered milling columns 2 and millable tapered drill rod short sections 4 in the milling working section. Based on the passage status of the casing 8 in step S2, determine the type of the pilot cone probe 1. The specific determination method is as follows:

[0069] Based on the damaged length L of casing 8 in step S1, if L≤10m, the milling working part uses one conical milling column 2 and one millable conical drill pipe short section 4; if 10m<L≤20m, the milling working part uses two conical milling columns 2 and two millable conical drill pipe short sections 4, and so on, to determine the number of conical milling columns 2 and millable conical drill pipe short sections 4 in the milling working part; based on the maximum diameter D of the casing 8 well gauge in step S2, if D>60mm, the guide cone probe 1 is selected as a probe type; if D≤60mm, the guide cone probe 1 is selected as a stepped type;

[0070] S4: Assemble and lower the milling tool for repairing the long-section bent and deformed casing. The hydraulic pressure 6 applies pressure, which drives the guide cone probe 1 to guide the milling working part to move downward in the casing 8. The milling opens up the channel of the bent and deformed casing, and the casing 8 is repaired.

[0071] Example 3

[0072] Using a milling tool for repairing large-section bent and deformed casing as described in Example 1, and applying a method for repairing large-section bent and deformed casing as described in Example 2, this invention performed casing repair work on well XX in an oilfield. The specific process is as follows:

[0073] S1: Damage inspection of sleeve 8;

[0074] First, logging instruments were used to check the damage to casing 8. Then, a conical lead mold 10mm smaller than the inner diameter of casing 8 was lowered into the well to check the diameter reduction, cracking degree and depth of casing 8. On-site inspection revealed that a large section of casing in the well, from 441.12m to 460.28mm deep, was bent, narrowed and cracked.

[0075] S2: Sleeve 8 pass inspection;

[0076] Φ73mm tubing can be flushed to the bottom of the well up to 646m with sand, and Φ108mm*8m well gauge can be used up to 450m. After being pulled out, it is bent and has severe scratches on the side. The maximum diameter is 89mm.

[0077] S3: Based on the damage to the casing 8 in step S1, determine that two tapered milling columns 2 and two millable tapered drill rod short sections 4 should be used in the milling working section; based on the passage of the casing 8 in step S2, select the pilot cone probe 1 as a probe type.

[0078] S4: Assemble and insert milling tools for repairing large sections of bent and deformed casing, such as... Figure 7 As shown, the hydraulic pressurizer 6 applies pressure, which drives the guide cone probe 1 to guide the milling working part to move downward in the sleeve 8, and the milling opens up the channel of the bent and deformed sleeve.

[0079] After successfully opening the curved and deformed casing passage of well XX, 17 Φ108mm uncoupling lining pipes were installed to line the section from 428.14 to 576.72m. After cementing and pressure testing, the well was put into production after a successful overhaul, achieving good economic benefits.

[0080] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A milling tool for repairing large sections of bent and deformed sleeves, characterized in that: The workpiece consists of, from bottom to top, a pilot taper probe (1), a milling working section, a weighted drill rod (5), a hydraulic pressure device (6), and a drill rod (7), connected in sequence. The milling working section includes, from bottom to top, several conical milling columns (2) and millable conical drill rod short sections (4) connected in sequence. The conical milling columns (2) at the lower end of the milling working section are fixedly connected to the upper part of the pilot taper probe (1), and the millable conical drill rod short sections (4) at the upper end of the milling working section are fixedly connected to the weighted drill rod (5). In use, the milling tool is placed inside the sleeve, and the hydraulic pressure device (6) is used to apply pressure, driving the pilot taper probe (1) to guide the milling tool. The working part moves downward inside the sleeve (8) and mills through the channel of the bent and deformed sleeve (8). The conical milling column (2) is hollow inside and includes a milling column upper connector (21), a milling column body (22), and a milling column lower connector (24) connected in sequence. The outside of the milling column body (22) is provided with a conical alloy (23). The conical alloy (23) includes an upper conical surface and a lower conical surface. The bottom surfaces of the upper and lower conical surfaces coincide. The cone height of the upper conical surface is less than the cone height of the lower conical surface. The length of the conical milling column (2) is 500 mm. The outer diameter range of the conical milling column (2) is 85~95 mm. m, 95~105mm, 105~110mm, 110~115mm, the conical milling column (2) and the millable conical drill rod short section (4) are connected by a rotatable universal joint (3), the rotatable universal joint (3) is hollow inside, including a movable joint upper connector (33), a movable short section (32) and a movable joint lower connector (31) connected in sequence, the upper part of the movable short section (32) is fixedly connected to the movable joint upper connector (33), the lower part of the movable short section (32) is provided with a ball key (34), the outer side of the ball key (34) is provided with a locking housing (35), the movable joint lower connector (31) The millable tapered drill rod section (4) is fixedly connected to the locking housing (35). The millable tapered drill rod section (4) is hollow inside and includes a drill rod section upper connector (41), a drill rod section body (43), and a drill rod section lower connector (45) connected in sequence. The outer diameter of the drill rod section upper connector (41) and the drill rod section lower connector (45) is the same and larger than the outer diameter of the drill rod section body (43). The upper connector milling alloy strip (42) is provided at the diameter change point of the connection between the drill rod section upper connector (41) and the drill rod section body (43). The lower connector milling alloy strip (44) is provided at the diameter change point of the connection between the drill rod section lower connector (45) and the drill rod section body (43).

2. The milling tool for repairing large-section bent and deformed sleeves according to claim 1, characterized in that: The guide cone probe (1) is a probe type with a hollow interior. It includes a fixedly connected upper guide cone connector (11) and a guide rod probe (13). The outer diameter of the upper guide cone connector (11) is greater than the outer diameter of the guide rod probe (13). A milled alloy strip (12) is provided at the connection and diameter change point between the upper guide cone connector (11) and the guide rod probe (13). The lower end face of the guide rod probe (13) is an inclined end face, and a probe alloy strip (14) is provided on the inclined end face.

3. The milling tool for repairing large-section bent and deformed sleeves according to claim 1, characterized in that: The pilot cone probe (1) is stepped and hollow inside. It includes a probe upper connector (111), a probe body (116), and a probe head (118) that are fixedly connected. The probe upper connector (111) is provided with a drain plug (112) in the middle and a retainer (113) at the lower end of the probe upper connector (111). The upper part of the probe body (116) is provided with a first-level step (115) and a second-level step (114) in sequence. The outer diameter of the retainer (113) is greater than the outer diameter of the second-level step (114) and the outer diameter of the first-level step (115). The probe head (118) is conical and is provided with a drain hole (117). The drain hole (117) is connected to the hollow interior of the pilot cone probe (1).

4. A milling tool for repairing large-section bent and deformed sleeves according to claim 2, characterized in that: The probe (13) is 700 mm long and has an outer diameter of 60 mm.

5. A milling tool for repairing large-section bent and deformed sleeves according to claim 1, characterized in that: The weighted drill rod (5) is an 18° slope weighted drill rod.

6. A method for repairing a ruptured casing with large-segment bending deformation, using a milling tool as described in claim 1, characterized in that: Includes the following steps: S1: Inspection of damage to sleeve (8); First, use logging instruments to check the damage to the casing (8). Then, lower a conical lead mold 10 mm smaller than the inner diameter of the casing (8) into the well to check the diameter reduction, cracking degree and depth of the casing (8). If the conical lead mold cannot pass through the casing (8), replace it with a smaller lead mold, reducing it by 3-4 mm each time. S2: Sleeve (8) pass inspection; Use Φ60.3mm or Φ73mm tubing to check the passage of the casing (8) through the duct, and lower a flexible well gauge with a wall thickness of 3mm*3~5m to check the degree of bending of the casing (8). The diameter of the well gauge should be 10mm smaller than the inner diameter of the casing (8). If it cannot pass through, replace it with a smaller well gauge, reducing the size by 3~4mm each time. S3: Based on the damage status of the casing (8) in step S1, determine the number of conical milling columns (2) and millable conical drill rod short sections (4) in the milling working section. Based on the passage status of the casing (8) in step S2, determine the type of the pilot cone probe (1). The specific judgment method is as follows: According to the damaged length L of the casing (8) in step S1, if L≤10m, the milling working part adopts 1 conical milling column (2) and 1 millable conical drill pipe short section (4); if 10m<L≤20m, the milling working part adopts 2 conical milling columns (2) and 2 millable conical drill pipe short sections (4), and so on, to determine the number of conical milling columns (2) and millable conical drill pipe short sections (4) in the milling working part; according to the maximum diameter D of the casing (8) well gauge in step S2, if D>60mm, the pilot cone probe (1) is selected as a probe type; if D≤60mm, the pilot cone probe (1) is selected as a stepped type. S4: Assemble and lower the milling tool for repairing the long-segment bending deformation and rupture of the sleeve. The hydraulic pressure device (6) applies pressure, which drives the guide cone probe (1) to guide the milling working part to move downward in the sleeve (8). The milling opens up the channel of the bending deformation and rupture of the sleeve, and the sleeve (8) is repaired.

Images