Anchoring mechanism of whipstock for open hole sidetrack drilling multilateral well

Abstract

The invention discloses a whipstock anchoring mechanism for an open hole sidetracking multilateral well, which comprises a mandrel, a whipstock is sleeved outside the mandrel, and a lower shear pin is arranged between the whipstock and the mandrel; the upper end of the whipstock is in matched contact with the limiting sleeve, and the joint of the whipstock and the limiting sleeve is sleeved with the sheath; the upper end of the limiting sleeve is connected with a fixing sleeve, a shearing sleeve is arranged in the fixing sleeve, and an upper shearing pin is arranged between the shearing sleeve and the mandrel; the lower end of the whipstock is sequentially connected with a circulating short section and a hand-releasing short section; a capturing short section is arranged at the lower end in the hand-releasing short section; the lower end of the mandrel is connected with a ball seat through a ball seat shear pin. The whipstock can be tripped into any position of the bottom of an open hole well, the requirements for the rule degree of the well wall of the open hole well section and the stratum strength are low, and the influence of the well diameter expansion rate on the anchoring stability of the whipstock is small; after the branch borehole drilling and completion operation is completed, additional procedures such as whipstock recovery or directional perforation do not need to be carried out, synchronous mining of the main borehole and the branch borehole can be achieved, the tripping times are reduced, and the operation cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of drilling technology, and in particular to a directional anchoring mechanism for open-hole sidetracking branch wells. Background Technology

[0002] As offshore oil and gas field development enters its mid-to-late stages, branch well technology has become a crucial approach to enhancing reservoir utilization and recovery rates. This technology involves drilling multiple branch wells within the main wellbore to achieve multi-target, three-dimensional development of a single well, effectively improving reservoir development efficiency and economic returns. Open-hole sidetracking, as the core technology of branch wells, allows for secondary window opening in existing wells without the need for casing, saving over 30% in operating costs compared to traditional casing-based sidetracking. This technology is particularly suitable for unconventional resource development such as shale gas and tight oil. However, due to the complex geological conditions of the open-hole section (such as wellbore instability and irregular well diameter), the precise positioning and reliable fixation of the directional drilling rig have become major technical bottlenecks hindering the success of the process.

[0003] Within the current technological scope, there are three main types of open-hole sidetracking technology: First, open-hole suspended sidetracking technology. This technology uses the interaction between the drill bit and the wellbore to form an initial groove, and then gradually expands the window using differences in drill string stiffness and directional drilling pressure, ultimately forming a branch wellbore. However, the window geometry formed by this method is irregular, the wellbore trajectory control accuracy is low, and it easily leads to increased drill string vibration during subsequent drilling, significantly increasing the risk of drill string fatigue failure and affecting operational safety and efficiency. Second, using a permanent directional drilling rig in conjunction with a milling cone to mill the window. This technology uses the directional drilling rig to guide the milling cone for directional milling, forming a regular window. However, the fixation of the directional drilling rig relies on cementing or mechanical anchoring, which is prone to anchoring failure in open-hole sections due to irregular wellbore or insufficient formation strength. Furthermore, the anchoring performance of the directional drilling rig is significantly affected by the wellbore enlargement rate. Field data shows that the sidetracking failure rate of this technology is as high as 18% to 25%, severely limiting its applicability in complex formation conditions. Third, the application scenarios of the side drilling technology using stuck drills and falling objects to support the directional drilling device are limited, and its feasibility and economic benefits are both low. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a directional anchoring mechanism for open-hole side-drilling branch wells.

[0005] The present invention is achieved by the following technical solution.

[0006] An anchoring mechanism for a directional drilling branch well in open-hole drilling includes a mandrel, an directional device sleeved on the mandrel, and a lower shear pin between the directional device and the mandrel. The upper end of the directional device contacts a limiting sleeve, and a protective sleeve is fitted at the junction of the directional device and the limiting sleeve. A fixing sleeve is connected to the upper end of the limiting sleeve, and a shear sleeve is provided inside the fixing sleeve. An upper shear pin is provided between the shear sleeve and the mandrel. A circulation sub and a release sub are connected sequentially to the lower end of the directional device, and a capture sub is provided at the lower end of the release sub. The lower end of the mandrel is connected to a ball seat via a ball seat shear pin.

[0007] Furthermore, a connector is connected to the upper end of the mandrel.

[0008] Furthermore, the upper part of the outer periphery of the mandrel is provided with a circular hole for installing an upper shear pin, and the two ends of the circular hole are provided with grooves for placing a second sealing ring and a third sealing ring; the middle part of the outer periphery of the mandrel is provided with a circular hole for installing a lower shear pin; the lower part of the mandrel is provided with a through hole corresponding to the bypass hole of the circulation short section, and the two ends of the through hole are provided with grooves for placing a fifth sealing ring and a sixth sealing ring.

[0009] Furthermore, the lower part of the mandrel is an elastic claw structure, and a certain number of screw holes for mounting ball seat shear pins are provided on the outer periphery of the elastic claw.

[0010] Furthermore, the upper part of the inclined device is an inclined surface at a certain angle, and a screw hole connected to the central hole of the inner circumference is provided on the inclined surface facing away from the outer circumference. A lower shear pin is provided in the screw hole, and a fourth sealing ring is provided between the lower shear pin and the screw hole of the inclined device.

[0011] Furthermore, the middle of the outer periphery of the limiting sleeve is provided with a step that contacts the upper end of the inclined device, and the lower part of the outer periphery is provided with a V-shaped inclined surface that contacts the upper inclined surface of the inclined device.

[0012] Furthermore, the outer periphery of the circulating short section is provided with a certain number of bypass holes that connect to the central hole.

[0013] Furthermore, the upper part of the inner circumference of the capture section is provided with a hemispherical reduced-diameter structure for capturing the ball seat.

[0014] Furthermore, the outer periphery of the ball seat is provided with a groove for installing the seventh sealing ring, and the lower part of the inner periphery is provided with a tapered reduced-diameter structure for receiving the soluble ball.

[0015] Furthermore, a first sealing ring is provided between the upper shear pin and the shear sleeve.

[0016] This application has the following beneficial effects.

[0017] This invention involves individually inserting the directional drilling rig to the designed well depth, pumping cement to fix the directional drilling rig, removing the insertion tool and leaving the directional drilling rig downhole, and then using a milling cone for window-opening side-drilling. This invention can be inserted to any position at the bottom of an open hole, with lower requirements on the regularity of the wellbore wall and formation strength. The anchoring stability of the directional drilling rig is less affected by the wellbore enlargement rate. The window geometry formed by the directional drilling rig is regular, resulting in high accuracy in wellbore trajectory control and ensuring the passage of subsequent drilling tools. After completing the branch well drilling and completion operations, no additional processes such as directional drilling rig retrieval or directional perforation are required, enabling simultaneous production of the main wellbore and branch wellbore. Compared with directional drilling rig retrieval technology and directional perforation technology, this reduces the number of tripping operations and significantly lowers operating costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the present invention after it has been lowered into the well; Figure 2 This is a schematic diagram of the structure of the present invention after the soluble ball is thrown; Figure 3 This is a schematic diagram of the upper and lower shear pins after shearing according to the present invention; Figure 4 This is a schematic diagram of the ball seat falling into the capture section after high displacement pressurization according to the present invention; Figure 5 This is a schematic diagram illustrating the recycling of the mandrel and other structures of this invention; Figure 6 This is a schematic diagram of the structure for leaving the well in this invention; Figure 7 This is a schematic diagram of the oblique actuator structure of the present invention; Figure 8 This is a schematic diagram of the limiting sleeve structure of the present invention; Figure 9 This is a schematic diagram of the mandrel structure of the present invention.

[0019] Among them, 1. upper connector, 2. mandrel, 3. fixed sleeve, 4. upper shear pin, 5. limiting sleeve, 6. protective cover, 7. inclined device, 8. lower shear pin, 9. circulating short section, 10. ball seat, 11. ball seat shear pin, 12. release short section, 13. capture short section, 14. first sealing ring, 15. second sealing ring, 16. third sealing ring, 17. fourth sealing ring, 18. fifth sealing ring, 19. sixth sealing ring, 20. seventh sealing ring, 21. shear sleeve, 22. soluble ball. Detailed Implementation

[0020] The present patent application will be further described below with reference to the accompanying drawings and embodiments.

[0021] like Figure 1-9As shown, a directional anchoring mechanism for open-hole side-drilling branch wells includes an upper connector 1, a mandrel 2, a directional anchor 7, a limiting sleeve 5, a shear sleeve 6, a fixing sleeve 3, a shear sleeve 21, an upper shear pin 4, a lower shear pin 8, a circulation sub 9, a release sub 12, a capture sub 13, a ball seat 10, and a ball seat shear pin 11.

[0022] The mandrel 2 is threadedly connected to the upper connector 1 and is located inside the shear sleeve 21, the limiting sleeve 5, the inclined device 7, and the circulation short section 9.

[0023] The lower end of the slant 7 is sequentially threaded with a circulating short section 9 and a release short section 12. The upper end of the slant 7 is in contact with the limiting sleeve 5. A protective sleeve 6 is disposed on the outer periphery of the slant 7 and the limiting sleeve 5 and is threadedly connected to the limiting sleeve 5 to fix the slant 7 and the limiting sleeve 5. The upper end of the limiting sleeve 5 is connected to a fixing sleeve 3. A shearing sleeve 21 is disposed inside the fixing sleeve 3. An upper shearing pin 4 is disposed between the shearing sleeve 21 and the spindle 2. A lower shearing pin 8 is disposed between the spindle 2 and the slant 7. A ball seat 10 is disposed at the lower end of the inner periphery of the spindle 2. A ball seat shearing pin 11 is disposed between the ball seat 10 and the spindle 2. The capture short section 13 is threadedly connected to the lower end of the release short section 12.

[0024] A first sealing ring 14 is provided between the upper shear pin 4 and the shear sleeve 21; a second sealing ring 15 and a third sealing ring 16 are provided between the spindle 2 and the shear sleeve 21; a fifth sealing ring 18 and a sixth sealing ring 19 are provided between the spindle 2 and the circulating short section 9; a fourth sealing ring 17 is provided between the lower shear pin 8 and the screw hole of the oblique device 7; and a seventh sealing ring 20 is provided between the ball seat 10 and the inner circumference of the spindle 2. Specifically, the first sealing ring 14 is installed in the groove inside the circular hole on the outer circumference of the upper shear sleeve 21; the second sealing ring 15 and the third sealing ring 16 are installed in the upper and lower grooves of the upper through hole on the outer circumference of the spindle 2, respectively; the fifth sealing ring 18 and the sixth sealing ring 19 are installed in the upper and lower grooves of the lower through hole on the outer circumference of the spindle 2, respectively; the fourth sealing ring 17 is installed on the outer circumference of the lower shear pin 8; and the seventh sealing ring 20 is installed on the upper part of the outer circumference of the ball seat 10.

[0025] Specifically, the limiting sleeve 5 is a hollow cylindrical structure. The upper part of the outer periphery is provided with an external thread that connects to the fixing sleeve 3. The middle part of the outer periphery is provided with an external thread that connects to the protective sleeve 6. The middle part of the outer periphery is provided with a step that contacts the upper end of the inclined device 7. The lower part of the outer periphery is provided with a V-shaped inclined surface that contacts the upper inclined surface of the inclined device 7.

[0026] The fixing sleeve 3 is a hollow cylindrical structure. The lower end of its inner circumference is provided with an internal thread that connects to the limiting sleeve 5. The middle part of the inner circumference is provided with a step, and a shearing sleeve 21 is provided at the step. The shearing sleeve 21 is a hollow cylindrical structure. Its upper end contacts the inner circumferential step of the fixing sleeve 3. The outer circumference is provided with a stepped threaded hole and a groove for placing the first sealing ring 14.

[0027] The sheath 6 is a hollow cylindrical structure, and the upper part of its inner circumference is provided with an internal thread that connects to the limiting sleeve 5.

[0028] The directional device 7 is a hollow structure with an upper part consisting of an inclined surface at a certain angle, which is used for the milling cone to move on the inclined surface to form a branch well. A screw hole is provided on the outer periphery of the inclined surface to connect to the central hole on the inner periphery. The lower part of the directional device 7 is provided with a male thread that connects to the circulation sub 9.

[0029] The mandrel 2 is a hollow cylindrical structure. Its upper outer circumference has an external thread for connection to the upper connector 1. The upper middle part of its outer circumference has a circular hole for mounting the upper shear pin 4. Both ends of the circular hole have grooves for placing the second sealing ring 15 and the third sealing ring 16. The middle part of its outer circumference has a circular hole for mounting the lower shear pin 8. The lower part of its outer circumference has a through hole corresponding to the through hole on the outer circumference of the circulation stub 9. Both ends of the through hole have grooves for placing the fifth sealing ring 18 and the sixth sealing ring 19. The lower part of the mandrel 2 has an elastic claw structure. The top of the elastic claw is located at the lower part of the male thread of the circulation stub 9. The outer circumference of the elastic claw has a certain number of screw holes for mounting the ball seat shear pin 11.

[0030] The circulating short section 9 is a hollow cylindrical structure with a certain number of bypass holes in the middle of its outer periphery that connect to the central hole. The upper and lower ends are respectively provided with threads that connect to the inclined device 7 and the release short section 12.

[0031] The release section 12 is a hollow cylindrical structure. The upper end is provided with a female thread that connects to the circulation section 9, and the lower end is provided with a male thread that connects to other tools. The lower part of the inner circumference is provided with a step and an internal thread that connects to the capture section 13. The upper part of the inner circumference of the capture section 13 is provided with a hemispherical reduced diameter for capturing the ball seat 10.

[0032] The ball seat 10 is a hollow cylindrical structure with a groove on the outer periphery for installing the seventh sealing ring 20, a certain number of threaded holes on the lower part of the outer periphery for installing the ball seat shear pin 11, and a tapered reduced-diameter structure on the lower part of the inner periphery to receive the ball rolling off the column and achieve a seal.

[0033] The directional drilling mandrel and large-diameter anchor of the present invention are used to run the branch well window opening system. The drilling fluid flows in from inside the tool mandrel 2 and flows out to the annulus through the bypass hole on the outer periphery of the circulation sub 9 and the internal channel of the anchor, ensuring the circulation of drilling fluid in the tubing and protecting the fluid level in the wellbore. After the directional drilling rig 7 is lowered to the preset position, the tool face of the directional drilling rig 7 can be adjusted by circulating drilling fluid and using other tools. Once the tool face is determined, the anchor is mounted. Then, a soluble ball 22 is dropped into the tubing from the wellhead. The soluble ball 22 rolls to the tool ball seat 10. The lower part of the inner circumference of the ball seat 10 has a tapered diameter reduction structure to catch the ball rolling off the tubing, thus sealing the internal channel of the anchor. Cement is pumped from the wellhead and enters the annulus through the bypass hole of the circulation sub 9, forming a cement plug below the directional drilling rig 7. The cement plug solidifies and stably fixes the directional drilling rig 7 to the open hole wall. The mandrel 2 is pressed down, cutting the pins between the mandrel 2 and the shear sleeve 21 and the directional drilling rig 7 respectively. The bypass hole of the circulation sub 9 is closed. Since a sealing ring is installed on the outer circumference of the mandrel 2, the sealing between the mandrel 2 and the limiting sleeve 5 and the circulation sub 9 is ensured, increasing the discharge rate inside the tubing. The ball seat 10 and the ball seat set on the lower part of the outer circumference of the mandrel 2... The shear pin 11, soluble ball 22, and ball seat 10 fall together into the hemispherical structure inside the capture sub 13, lifting the tubing string. The elastic claw at the lower end of the mandrel 2 contacts and contracts with the inner hole of the circulation sub 9. The elastic claw contracts to the inner hole of the circulation sub 9, and the tubing string continues to be lifted. The elastic claw at the lower end of the mandrel 2 moves to the lower end of the inner circumference of the limiting sleeve 5 and extends. The tubing string continues to be slowly lifted, and the elastic claw recovers the limiting sleeve 5, sheath 6, and other parts together to the wellhead. At this time, the directional drilling device 7, circulation sub 9, and release sub 12 remain downhole. Subsequently, the opening milling cone is lowered, and the milling cone moves along the inclined surface of the directional drilling device 7 to form a branch wellbore. The soluble ball 22 is a biodegradable material. Under certain downhole temperature and pressure conditions, it reacts with the bottomhole solution. Within a certain time, the material effectively seals the drilling fluid of the side-drilled branch well from moving down to the main wellbore and contaminating the reservoir. The material automatically degrades within the designed time to achieve production in the main wellbore.

[0034] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A directional drilling anchoring mechanism for open-hole side-drilling branch wells, comprising a mandrel (2), characterized in that: The mandrel (2) is fitted with a slant (7), and a lower shear pin (8) is provided between the slant (7) and the mandrel (2); the upper end of the slant (7) is in contact with the limiting sleeve (5), and a protective sleeve (6) is fitted at the junction of the slant (7) and the limiting sleeve (5); a fixing sleeve (3) is connected to the upper end of the limiting sleeve (5), and a shearing sleeve (21) is provided inside the fixing sleeve (3), and an upper shear pin (4) is provided between the shearing sleeve (21) and the mandrel (2); the lower end of the slant (7) is connected to a circulation short section (9) and a release short section (12) in sequence, and a capture short section (13) is provided inside the lower end of the release short section (12); the lower end of the mandrel (2) is connected to a ball seat (10) through a ball seat shear pin (11).

2. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The upper end of the mandrel (2) is connected to the connector (1).

3. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The upper part of the outer periphery of the mandrel (2) is provided with a round hole for installing the upper shear pin (4), and the two ends of the round hole are provided with grooves for placing the second sealing ring (15) and the third sealing ring (16); the middle part of the outer periphery of the mandrel (2) is provided with a round hole for installing the lower shear pin (8); the lower part of the mandrel (2) is provided with a through hole corresponding to the bypass hole of the circulation short section (9), and the two ends of the through hole are provided with grooves for placing the fifth sealing ring (18) and the sixth sealing ring (19).

4. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The lower part of the mandrel (2) is an elastic claw structure, and a certain number of screw holes for mounting ball seat shear pins (11) are provided on the outer periphery of the elastic claw.

5. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The upper part of the inclined device (7) is an inclined surface at a certain angle. A screw hole is provided on the outer periphery of the inclined surface, which is connected to the central hole of the inner periphery. A lower shear pin (8) is provided in the screw hole. A fourth sealing ring (17) is provided between the lower shear pin (8) and the screw hole of the inclined device.

6. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The limiting sleeve (5) has a step in the middle of its outer periphery that contacts the upper end of the inclined device (7), and a V-shaped inclined surface in the lower part of its outer periphery that contacts the upper inclined surface of the inclined device (7).

7. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The outer periphery of the circulating short section (9) is provided with a certain number of bypass holes that connect to the central hole.

8. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: The upper inner circumference of the capture section (13) is provided with a hemispherical reduced diameter structure for capturing the ball seat (10).

9. The directional drilling anchoring mechanism for open-hole sidetracking branch wells according to claim 1, characterized in that: The ball seat (10) has a groove on its outer periphery for installing the seventh sealing ring (20), and a tapered reduced-diameter structure on its lower inner periphery for receiving the soluble ball (22).

10. The directional drilling anchoring mechanism for open-hole side-drilling branch wells according to claim 1, characterized in that: A first sealing ring (14) is provided between the upper shear pin (4) and the shear sleeve (21).

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