Downhole self-ballistic coring devices, tool strings, and related methods

Abstract

This invention discloses a downhole self-dropped ball coring device, tool string, and related methods. The self-dropped ball coring device includes: a self-dropping mechanism and a coring tool; the self-dropping mechanism is located at the upper end of the coring tool and is fixedly connected to it; the self-dropping mechanism includes a sleeve assembly and a steel ball chuck; the sleeve assembly includes an inner cylinder section and an outer cylinder section sleeved around the inner cylinder section; the steel ball chuck is located inside the outer cylinder section and below the inner cylinder section; the steel ball chuck is used to hold steel balls; the inner cylinder section, after the coring device is lowered to a preset position, is pushed downwards relative to the outer cylinder section by the drill string connected to the inner cylinder section, enters the steel ball chuck, opens the steel ball chuck, and drops the steel balls. This invention solves the problem of not being able to drop balls from the wellhead in deep and ultra-deep well coring operations due to the presence of check valves, by using a self-dropping function to avoid drilling fluid directly scouring the core and affecting the coring quality.

Description

Technical Field

[0001] This invention relates to the field of coring technology in petroleum exploration, and particularly to downhole self-dropped ball coring devices, tool strings, and related methods. Background Technology

[0002] During drilling, drilling fluid needs to be circulated and pumped in before coring. The drilling fluid flows through the inner cylinder of the coring tool, carrying away sediment and cuttings from the bottom of the well to avoid adverse effects such as core blockage or core grinding during coring. During coring, drilling fluid should be prevented from entering the inner cylinder to avoid directly eroding the core and affecting its quality. Therefore, a ball needs to be dropped from the wellhead onto the ball seat inside the coring tool to seal the inner cylinder.

[0003] However, in coring operations in deep and ultra-deep wells, check valves are required, making ball dropping impossible. If balls are dropped beforehand, there is a problem that the bottom sediment and cuttings inside the coring tool cannot be carried away. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a downhole self-feeding coring device, tool string and related methods that overcome or at least partially solve the above problems.

[0005] In a first aspect, embodiments of the present invention provide a downhole self-dropped coring device, comprising:

[0006] A self-throwing mechanism and a core-retrieving tool; the self-throwing mechanism is disposed at the upper end of the core-retrieving tool and is fixedly connected to the core-retrieving tool;

[0007] The self-throwing mechanism includes a sleeve assembly and a steel ball catcher. The sleeve assembly includes an inner cylinder section and an outer cylinder section sleeved on the outside of the inner cylinder section. The steel ball catcher is disposed inside the outer cylinder section and located at the lower part of the inner cylinder section. The steel ball catcher is used to hold steel balls.

[0008] The inner cylinder section is used to push the drill bit connected to the inner cylinder section downward relative to the outer cylinder section after the coring device is lowered to a preset position, enter the steel ball chuck, open the steel ball chuck, and release the steel ball.

[0009] In one embodiment, the outer wall of the inner cylinder section is provided with a first limiting boss and a second limiting boss; the first limiting boss and the second limiting boss are used to limit the relative movement stroke of the inner cylinder section and the outer cylinder section.

[0010] In one embodiment, the inner wall of the outer cylinder section is provided with a third limiting boss; in the state of the core-taking device being lowered, the third limiting boss limits the inner cylinder section; in the state of the core-taking device throwing the ball, the third limiting boss separates from the first limiting boss.

[0011] In one embodiment, the steel ball jaw is conical; a gap is provided on the conical surface of the cone; the gap serves as a channel for drilling fluid flow.

[0012] In one embodiment, the core-collecting tool includes: an upper connector and a lower connector;

[0013] The two ends of the upper connector are respectively connected to the inner cylinder short section and the upper drilling tool;

[0014] The two ends of the lower connector are respectively connected to the outer cylinder section and the core-taking tool at the bottom.

[0015] In one embodiment, the core-collecting tool further includes: an inner core-collecting cylinder and an outer core-collecting cylinder;

[0016] The core-collecting inner cylinder includes a ball-throwing section and a core-collecting section, with the ball-throwing section located above the core-collecting section;

[0017] A ball seat is provided at the lower end of the ball-throwing part.

[0018] In one embodiment, a drilling fluid flow hole is provided on the inner wall of the ball-throwing part;

[0019] The drilling fluid circulation hole is used as an inlet for the drilling fluid to circulate from the ball-feeding section into the outer cylinder of the core-taking section during the core-taking process.

[0020] In one embodiment, the core-taking tool further includes: a suspension bearing;

[0021] The suspension bearings are connected to the bottom end of the outer cylinder section and the top end of the core-taking inner cylinder, respectively.

[0022] Secondly, embodiments of the present invention provide a downhole coring tool string, comprising:

[0023] The coring device as described in the first aspect above, and the upper drill string connected to the coring device.

[0024] Thirdly, embodiments of the present invention provide a method for extracting the core using the aforementioned core extraction toolchain, comprising:

[0025] The core sampling tool string is lowered to a predetermined position inside the well.

[0026] Push the upper drill bit, and the inner cylinder section connected to the drill bit moves downward and enters the steel ball chuck. Open the steel ball chuck, release the steel ball, and let the steel ball fall onto the ball seat in the ball release part.

[0027] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0028] This invention provides a downhole self-dropped ball coring device, tool string, and related method. The self-dropped ball coring device includes a self-dropping mechanism and a coring tool. The self-dropping mechanism includes a sleeve assembly and steel ball chucks. The sleeve assembly includes an inner cylinder section and an outer cylinder section, which are axially movable relative to each other. The inner cylinder section is connected to the upper drill string, and the outer cylinder section is connected to the lower coring tool. After the tool string formed by the self-dropped ball coring device is lowered to the bottom of the well, the upper drill string is pushed, causing the inner cylinder section to move relative to the outer cylinder section and enter the steel ball chucks. The steel ball chucks are gradually opened, thereby releasing the steel ball. The steel ball falls into the ball seat and seals the coring section of the coring tool. This prevents drilling fluid from entering the coring section and directly eroding the core, affecting the core quality, during subsequent coring operations. This effectively solves the problem of not being able to drop balls from the wellhead in deep and ultra-deep well coring operations where check valves are installed.

[0029] Furthermore, by setting a first limiting boss and a second limiting boss on the inner cylinder short section, and a third limiting boss on the outer cylinder short section, the inner and outer cylinder short sections are movably connected. This ensures that the two sections remain relatively stationary when the coring device is lowered, making them a single unit. It also allows the inner and outer cylinder short sections to be separated and the ball-throwing action to be completed simply by pushing the upper drill bit when the device is in the ball-throwing state. This makes the operation simple and convenient for technicians.

[0030] Furthermore, the conical surface of the steel ball chuck is provided with a gap for drilling fluid to flow through, and the inner wall of the ball dropping part in the core sampling device is provided with a flow inlet for drilling fluid to enter the annulus between the inner core cylinder and the outer core cylinder, so that the function of the drilling fluid to flush sand and rock cuttings in the tool string is not affected during the core sampling process.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0033] Figure 1 This is a schematic diagram of the downhole coring tool string structure in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the downhole self-feeding coring device in the lowering state according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the downhole self-feeding coring device in the feeding state according to an embodiment of the present invention;

[0036] Figure 4 This is a schematic diagram of the steel ball claw structure in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram of the stepped connecting section structure at the bottom of the outer cylinder short section in an embodiment of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Inner cylinder short section; 2. Outer cylinder short section; 3. Steel ball chuck; 4. Steel ball; 5. First limiting boss; 6. Second limiting boss; 7. Third limiting boss; 8. Upper connector; 9. Lower connector; 10. Ball throwing part; 11. Core taking part; 12. Ball seat; 13. Stepped connecting section; 14. Suspension bearing. Detailed Implementation

[0040] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0041] In a first aspect, embodiments of the present invention provide a downhole self-feeding coring device, referring to... Figure 1 , Figure 2 and Figure 3 As shown, it includes:

[0042] A self-throwing mechanism and a core-retrieving tool; the self-throwing mechanism is disposed at the upper end of the core-retrieving tool and is fixedly connected to the core-retrieving tool;

[0043] The self-throwing mechanism includes a sleeve assembly and a steel ball claw 3. The sleeve assembly includes an inner cylinder section 1 and an outer cylinder section 2 sleeved on the outside of the inner cylinder section 1. The steel ball claw 3 is disposed inside the outer cylinder section 2 and located at the lower part of the inner cylinder section 1. The steel ball claw 3 is used to hold a steel ball 4.

[0044] The inner cylinder section 1 is used to be pushed downward relative to the outer cylinder section 2 by the drill bit connected to the self-throwing mechanism after the coring device is lowered to a preset position, enter the steel ball chuck 3, open the steel ball chuck 3, and release the steel ball 4.

[0045] Deep and ultra-deep well coring operations are equipped with check valves, making it impossible to drop balls from the wellhead to seal the inner core cylinder and prevent drilling fluid from eroding the core. To address this engineering problem, this invention provides a downhole self-dropping ball coring device. This device includes a self-dropping ball mechanism and a coring tool connected to it at its lower part. During the lowering process of this self-dropping ball coring device, the inner cylinder section 1 and outer cylinder section 2 of the self-dropping ball mechanism remain relatively stationary. When the coring bit of the coring tool contacts the bottom of the well, it pushes the upper drill string downwards. The drill string connects to the inner cylinder section 1 in the coring mechanism, thereby causing the inner cylinder section 1 to move downwards and enter the ball chuck 3. The inner cylinder section 1 forces the ball chuck 3 to open, causing the steel ball 4 placed on the ball chuck 3 to fall onto the ball seat 12 inside the coring device, completing the automatic ball dropping operation. In this way, during the coring operation, due to the sealing function of the steel balls 4 on the inner cylinder of the coring tool, the drilling fluid can no longer enter the inner cylinder, thus avoiding the drilling fluid directly scouring the core and ensuring the core recovery rate.

[0046] Reference Figure 1 , Figure 2 and Figure 3 In one embodiment, a first limiting boss 5 and a second limiting boss 6 are provided on the outer wall of the inner cylinder section 1. The first limiting boss 5 and the second limiting boss 6 are used to limit the relative movement stroke of the inner cylinder section 1 and the outer cylinder section 2.

[0047] The first limiting boss 5 is set at a preset position in the axial direction of the inner cylinder short section 1, and the second limiting boss 6 is set at the upper end of the inner cylinder short section 1. The distance between the upper edge of the first limiting boss 5 and the lower edge of the second limiting boss 6 is determined based on experience, and must be sufficient to allow the inner cylinder short section 1 to move downwards and open the steel ball chuck 3.

[0048] Reference Figure 1 , Figure 2 and Figure 3 In one embodiment, a third limiting boss 7 is provided on the inner wall of the outer cylinder section 2. When the core extractor is in the lowering state, the third limiting boss 7 limits the inner cylinder section 1; when the core extractor is in the throwing state, the third limiting boss 7 separates from the first limiting boss 5.

[0049] The third limiting boss 7 is located at the upper end of the outer cylinder short section 2, during the lowering process of the core-taking device (refer to...). Figure 2 The lower edge of the third limiting boss 7 contacts the upper edge of the first limiting boss 5, and the two are in a relatively stationary state. At this time, the weight of the outer cylinder short section 2 and the core-retrieving tool connected to the lower part of the outer cylinder short section 2 is entirely borne by the first limiting boss 5 of the inner cylinder short section 1. During the core-retrieving device's ball-throwing process (refer to...), Figure 3As the inner cylinder section 1 is pushed downward relative to the outer cylinder section 2 by the upper drill bit, the third limiting boss 7 and the first limiting boss 5 separate, and the outer cylinder section 2 moves upward relative to each other. The maximum stroke is when the upper edge of the third limiting boss 7 resists the lower edge of the second limiting boss 6 of the inner cylinder section 1.

[0050] Reference Figure 2 , Figure 3 and Figure 4 In one embodiment, the steel ball chuck 3 is conical; a gap is provided on its conical surface; the gap serves as a channel for drilling fluid flow. During the lowering of the coring device, the steel ball 4 is located inside the steel ball chuck 3; during the ball dropping process of the coring device, the steel ball chuck 3 is opened by the inner cylinder short section 1 to realize the dropping of the steel ball 4.

[0051] Reference Figure 1 , Figure 2 and Figure 3 In one embodiment, the coring tool includes an upper connector 8 and a lower connector 9; the two ends of the upper connector 8 are respectively connected to the inner cylinder sub 1 and the upper drill bit; the two ends of the lower connector 9 are respectively connected to the outer cylinder sub 2 and the lower coring tool.

[0052] The inner cylinder section 1 of the self-throwing mechanism is detachably connected to the upper drill bit, and the intermediate component connecting them is the upper connector 8, for example, by a threaded connection. Similarly, the outer cylinder section 2 is connected to the lower coring tool by the intermediate connecting component, the lower connector 9, for example, by a threaded connection.

[0053] Reference Figure 1 In one embodiment, the core-retrieving tool further includes an inner core-retrieving cylinder and an outer core-retrieving cylinder. The inner core-retrieving cylinder includes a ball-throwing part 10 and a core-retrieving part 11, with the ball-throwing part 10 located above the core-retrieving part 11. A ball seat 12 is provided at the lower end of the ball-throwing part 10.

[0054] Reference Figure 1 In one embodiment, a drilling fluid circulation hole is provided on the inner wall of the ball-throwing section 10; the drilling fluid circulation hole is used as an inlet for the drilling fluid to circulate from the ball-throwing section 10 into the outer cylinder of the core-taking section 11 during the core-taking process.

[0055] The ball-dropping section 10 and the core-taking section 11 are separated by a ball seat 12. In the ball-dropping state of this self-dropping core-taking device, the steel ball 4 falls from the extended steel ball chuck 3 onto the ball seat 12, thus preventing drilling fluid from entering the core-taking section 11. At this time, the drilling fluid enters the annulus between the inner and outer core-taking cylinders through the drilling fluid inlet, without affecting the function of the drilling fluid in carrying away bottom sediment and cuttings.

[0056] Reference Figure 2 , Figure 3 and Figure 5In one embodiment, the core-taking tool further includes a suspension bearing 14; the suspension bearing 14 is connected to the bottom end of the outer cylinder section 2 and the upper end of the core-taking inner cylinder, respectively.

[0057] The lower part of the outer cylinder section 2 is provided with a stepped connecting section 13, which connects to the lower connector 9 and the suspension bearing 14 respectively, so as to suspend the inner core cylinder above the outer core cylinder, achieving the function of double cylinder single action, that is, the outer core cylinder rotates while the inner core cylinder basically does not rotate. Because the core drill bit connected to the outer core cylinder grinds the rock, while the inner core cylinder remains basically stationary during drilling, the extracted rock core can be avoided from disturbance and maintain its original state, thus resulting in higher core quality.

[0058] Secondly, embodiments of the present invention provide a downhole coring tool string, including: the coring device described in the first aspect above, and an upper drilling tool connected to the coring device.

[0059] Thirdly, embodiments of the present invention provide a method for extracting the core using the core extraction toolchain of the second aspect, comprising:

[0060] The coring tool string is lowered to the predetermined position inside the well.

[0061] Push the upper drill bit, and the inner cylinder short section connected to the upper drill bit moves downward and enters the steel ball chuck. The steel ball chuck is opened, and the steel ball is dropped, so that the steel ball falls into the ball seat in the ball dropping part.

[0062] The downhole self-dropping coring device in this coring tool string is detachably installed on the tool string, allowing for repeated use. When the coring tool string is lowered to the position where the coring drill bit contacts the bottom of the well, simply pushing the upper drill string quickly drops the ball and seals the coring section. This prevents drilling fluid from entering the coring section and eroding the core during coring, thus avoiding impact on coring quality. Furthermore, it is easy to operate and user-friendly for technicians.

[0063] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A downhole self-feeding ball coring device, characterized in that, include: A self-throwing mechanism and a core-retrieving tool; the self-throwing mechanism is disposed at the upper end of the core-retrieving tool and is fixedly connected to the core-retrieving tool; The self-throwing mechanism includes a sleeve assembly and a steel ball catcher. The sleeve assembly includes an inner cylinder section and an outer cylinder section sleeved on the outside of the inner cylinder section. The steel ball catcher is disposed inside the outer cylinder section and located at the lower part of the inner cylinder section. The steel ball catcher is used to hold steel balls. The inner cylinder section is used to push the drill bit connected to the inner cylinder section downward relative to the outer cylinder section after the coring device is lowered to a preset position, enter the steel ball chuck, open the steel ball chuck, and release the steel ball.

2. The apparatus as claimed in claim 1, characterized in that, The outer wall of the inner cylinder section is provided with a first limiting boss and a second limiting boss; the first limiting boss and the second limiting boss are used to limit the relative movement stroke of the inner cylinder section and the outer cylinder section.

3. The apparatus as described in claim 2, characterized in that, The inner wall of the outer cylinder section is provided with a third limiting boss; when the core-taking device is lowered, the third limiting boss limits the inner cylinder section; when the core-taking device is in the ball-throwing state, the third limiting boss separates from the first limiting boss.

4. The apparatus as described in claim 3, characterized in that, The steel ball jaws are conical; a gap is provided on the conical surface of the cone; the gap serves as a channel for drilling fluid flow.

5. The apparatus as described in claim 4, characterized in that, The core extraction tool includes: an upper connector and a lower connector; The two ends of the upper connector are respectively connected to the inner cylinder short section and the upper drilling tool; The two ends of the lower connector are respectively connected to the outer cylinder section and the core-taking tool at the bottom.

6. The apparatus as claimed in claim 5, characterized in that, The core extraction tool also includes: an inner core extraction cylinder and an outer core extraction cylinder; The core-collecting inner cylinder includes a ball-throwing section and a core-collecting section, with the ball-throwing section located above the core-collecting section; A ball seat is provided at the lower end of the ball-throwing part.

7. The apparatus as claimed in claim 6, characterized in that, The inner wall of the ball-throwing part is provided with drilling fluid flow holes; The drilling fluid circulation hole is used as an inlet for the drilling fluid to circulate from the ball-feeding section into the outer cylinder of the core-taking section during the core-taking process.

8. The apparatus as claimed in claim 6, characterized in that, The core-taking tool also includes: a suspension bearing; The suspension bearings are connected to the bottom end of the outer cylinder section and the top end of the core-taking inner cylinder, respectively.

9. A downhole coring tool string, characterized in that, include: The coring apparatus as described in any one of claims 1-8, and the upper drill string connected to the coring apparatus.

10. A method for extracting cores using the core extraction toolchain as described in claim 9, characterized in that, include: The core sampling tool string is lowered to a predetermined position inside the well. Push the upper drill bit, and the inner cylinder section connected to the drill bit moves downward and enters the steel ball chuck. Open the steel ball chuck, release the steel ball, and let the steel ball fall onto the ball seat in the ball release part.

Images