A piston sealing device for closed coring in drilling

Abstract

The present invention relates to a piston sealing device for drilling closed coring in the technical field of oil drilling coring, including an outer core barrel, a coring bit, an aluminum alloy inner barrel assembly, a sealing bushing, shear pins, core grippers, and a sealing piston assembly. The closed piston assembly consists of a piston plug, a shear body, a piston body, a piston sealing head, and a pressure head, which are sequentially connected by threads and placed in the inner cavity formed by the coring bit, the core grippers, and the sealing bushing. It is connected to the sealing bushing through shear pins, presses a sealing ring with the coring bit, and jointly forms the lower seal of the closed coring tool with the core gripper sealing ring to complete the isolation of the closed liquid and the drilling fluid. By applying the device of this patent, during the assembly of the drilling closed coring tool, especially during the continuous coring process, it is not necessary to lift the outer barrel assembly out of the wellhead. The inner barrel assembly can be directly lifted out of the outer barrel to complete the core extraction construction. When reassembling, directly connect the sealing piston assembly to the lower part of the inner barrel assembly, and then insert it into the outer barrel assembly.

Description

Technical Field

[0001] The present invention relates to the technical field of oil drilling coring tools, and particularly relates to a piston sealing device for closed coring in drilling and a method using the piston sealing device. Background Art

[0002] CN93228726.3 "Drilling Closed Coring Locking and Sealing Device" adopts a clamp seat joint and a clamp seat structure, and the sealing piston is controlled by a locking pin and a spring. The structure of the sealing piston is different from that of the sealing device of the present invention and is applicable to different closed coring tools.

[0003] CN201520369015.5 "A Closed Coring Drill String" fixes the sealing piston and the coring bit with a pin, and the structure of this invention tool is different from that of the present invention.

[0004] CN91218861.8 "Closed Coring Tool", the sealing piston is fixed on the thrust sealing ring between the claw sleeve joint and the core claw sleeve by a pin. The structure of this tool's joint is different from that of the present invention, and the structure and sealing method of the sealing piston are different. Summary of the Invention

[0005] The purpose of the present invention is to provide a piston sealing device suitable for closed coring in drilling in view of the problems existing in the prior art. At the same time, the present invention also provides a method for closed coring using this device.

[0006] The technical solution of the present invention includes:

[0007] A piston sealing device for closed coring in drilling, comprising an outer core barrel, a coring bit, an aluminum alloy inner barrel assembly, a sealing bushing, shear pins, core claws, and a sealing piston assembly.

[0008] The core claws and the sealing bushing are sequentially connected to the aluminum alloy inner barrel assembly by threads, and the upper part is connected to the suspension system by threads and placed in the inner cavities of the coring bit and the outer core barrel. A sealing element is pressed between the core claws and the coring bit. The closed piston assembly is placed in the inner cavity formed by the coring bit, the core claws, and the sealing bushing, is connected to the sealing bushing by shear pins, and a sealing element is pressed between it and the coring bit.

[0009] Before drilling coring, the inner coring barrel is filled with a closed liquid. The upper part of the inner coring barrel is closed by a plug, and the lower part is closed by the sealing piston assembly. Sealing is completed by the sealing elements between the coring bit, the core claws, and the sealing piston assembly, so that the closed liquid is completely isolated from the bottom-hole drilling fluid. After the tool enters the well, 4 shear pins are relied on to prevent the piston from moving upward, so that the closed liquid does not flow out of the inner cavity in advance.

[0010] The above solution further includes:

[0011] The closed piston assembly is connected in sequence by a piston plug, a shear body, a piston body, a piston seal head, and a pressure head through threads. The shear body bears the force of the shear pin being cut, and its material is alloy steel. The other components of the piston are processed from aluminum alloy. The shear body is axially machined with 3 equally spaced shear pin holes, and a total of 12 pin holes are evenly distributed in 4 groups in the circumferential direction. The shear body is connected to the sealing bushing through shear pins, and the cooperation between the pin holes and the shear pins can be adjusted by axially moving the piston so that the sealing ring on the piston seal head and the inner hole of the core bit are always in a sealed working state.

[0012] The outer diameter of the shear body is larger than the inner diameter of the core bit and smaller than the inner diameter of the aluminum alloy inner barrel, so that it can move axially freely in the inner barrel and cannot fall out of the core bit.

[0013] Before the drilling core sampling starts, the shear pin is cut by applying a drilling pressure. After the core sampling starts, the core enters the inner barrel through the core bit and pushes the sealed piston assembly upward. The shear body is provided with a closed liquid flow channel, which reduces the flow resistance of the closed liquid during the upward movement of the piston.

[0014] The advantages of the present invention are as follows: By applying the device of this patent, during the assembly of the drilling closed core sampling tool, especially during the continuous core sampling process, it is not necessary to lift the outer barrel assembly out of the wellhead. The inner barrel assembly can be directly lifted out of the outer barrel to complete the core extraction operation. During reassembly, the sealed piston assembly is directly connected to the lower part of the inner barrel assembly, and then inserted into the outer barrel assembly. This improves the assembly efficiency of the closed drilling core sampling tool, reduces the labor intensity, and increases the timeliness of the core sampling operation. Description of the Drawings

[0015] Figure 1 It is a schematic structural diagram of a piston seal device for drilling closed core sampling of the present invention.

[0016] Figure 2 It is a schematic sectional view of a piston seal device for drilling closed core sampling of the present invention.

[0017] In the figure: 1. Outer core barrel, 2. Core bit, 3. Inner core barrel, 4. Sealing bushing, 5. Shear pin, 6. Core catcher, 7. Core catcher sealing ring, 8. Piston sealing ring, 9. Sealed piston assembly, 9-1. Piston plug, 9-2. Shear body, 9-3. Piston body, 9-4. Piston seal head, 9-5. Pressure head, 10. Closed liquid, 11. Piston pin hole. Detailed Embodiment

[0018] The technical solution of the present invention will be further elaborated in detail below in combination with embodiments.

[0019] Refer to Figure 1 and Figure 2, A schematic structural diagram and a sectional view of a piston sealing device for closed coring in drilling, including an outer core barrel 1, a coring bit 2, an aluminum alloy inner barrel assembly 3, a sealing bushing 4, shear pins 5, a core catcher 6, and a sealing piston assembly 9.

[0020] The core catcher 6 and the sealing bushing 4 are sequentially connected to the aluminum alloy inner barrel assembly 3 by threads and are placed in the inner cavity formed by the coring bit 2 and the outer core barrel 1. A core catcher sealing ring 7 is pressed between the core catcher 6 and the coring bit 2. The sealing piston assembly 9 is placed in the inner cavity formed by the coring bit 2, the core catcher 6, and the sealing bushing 4, is connected to the sealing bushing 4 by shear pins 5, and a piston sealing ring 8 is pressed between it and the coring bit 2.

[0021] Before the tool is lowered into the well, the inner coring barrel is filled with a sealing fluid 10. The upper part of the inner coring barrel is sealed by a plug, and the lower part is sealed by the sealing piston assembly 9. The sealing is completed by the sealing elements 7 and 8 between the coring bit 2, the core catcher 6, and the sealing piston assembly 8, so that the sealing fluid 10 is completely isolated from the bottom-hole drilling fluid. After the tool is lowered into the well, 4 shear pins 5 are relied on to prevent the piston from moving upward, so that the sealing fluid does not flow out of the inner cavity in advance.

[0022] The sealing piston assembly 9 is sequentially connected by threads with a piston plug 9-1, a shear body 9-2, a piston body 9-3, a piston sealing head 9-4, and a pressure head 9-5. The shear body 9-2 bears the force of the shear of the pin 5, and its material is alloy steel. The other parts of the piston are processed from aluminum alloy. The shear body 9-2 is axially machined with 3 shear pin holes 11 evenly distributed along the axis, and a total of 12 pin holes are evenly distributed in 4 groups in the circumferential direction. The shear body 9-2 is connected to the sealing bushing 4 by shear pins 5. The cooperation between the pin holes 11 and the shear pins 5 can be adjusted by axially moving the piston, so that the sealing ring 8 on the piston sealing head 9-4 and the inner hole of the coring bit 2 are always in a sealed working state.

[0023] The outer diameter of the shear body 9-2 is larger than the inner diameter of the coring bit 2 and at the same time smaller than the inner diameter of the aluminum alloy inner barrel 3, so that it can axially move freely in the inner barrel 3 and cannot fall out of the coring bit 2.

[0024] Before the drilling coring starts, the shear pins 5 are cut off by applying a drilling pressure. After the coring starts, the core enters the inner cavity through the coring bit 2 and pushes the sealing piston assembly 9 upward. The shear body 9-2 is provided with a sealing fluid flow channel. During the upward movement of the piston, the sealing fluid is discharged from the lower part of the piston assembly to wrap the core, preventing the drilling fluid from contaminating the core.

[0025] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of the present invention. The scope of the present invention is defined by the claims and their equivalents.

Claims

1. A piston sealing device for closed coring in drilling, comprising an outer core barrel (1), a coring bit (2), an aluminum alloy inner barrel assembly (3), a sealing bushing (4), shear pins (5), core catchers (6), and a sealing piston assembly (9), characterized in that, The core claw (6), the sealing sleeve (4) and the aluminum alloy inner tube assembly (3) are connected in sequence through threads and are placed in the inner cavities of the coring drill bit (2) and the outer core tube (1); a first sealing element (7) is provided between the core claw (6) and the coring drill bit (2); the sealing piston assembly (9) is placed in the inner cavity formed by the coring drill bit (2), the core claw (6) and the sealing sleeve (4), is connected to the sealing sleeve (4) through a shear pin (5), and a second sealing element (8) is pressed between the core claw (6) and the coring drill bit (2); The sealing piston assembly (9) is mainly composed of a piston plug (9-1), a shear body (9-2), a piston body (9-3), a piston sealing head (9-4), and a pressure head (9-5) which are threadedly connected in sequence; the shear body (9-2) is processed with three shear pin holes (11) equidistantly distributed along the axial direction, and a total of four groups of 12 pin holes are evenly distributed in the circumferential direction; the shear body (9-2) is connected to the sealing sleeve (4) through the shear pin (5); the three pin holes can be axially adjusted to cooperate with the shear pin (5) so that the second sealing element (8) is always in a sealing working state between the sealing piston assembly (9) and the core drill bit (2); Before coring, the sealing fluid (10) is in a sealed cavity formed by the coring drill bit (2), the aluminum alloy inner tube assembly (3), the sealing sleeve (4), and the sealing piston assembly (9), and is completely isolated from the bottom hole drilling fluid; The shear pin (5) is sheared off by applying drilling pressure. After coring begins, the core enters the inner cavity through the coring drill bit (2), and pushes the sealing piston assembly (9) upward. The shear body (9-2) is provided with a sealing liquid flow channel. During the upward movement of the piston, the sealing liquid is discharged from the bottom of the piston assembly to wrap the core, thereby preventing the drilling fluid from contaminating the core.

2. The piston sealing device for closed coring in drilling according to claim 1, characterized in that: The outer diameter of the shear body (9-2) is larger than the inner diameter of the coring drill bit (2) and smaller than the inner diameter of the aluminum alloy inner cylinder assembly (3), so that the shear body (9-2) can move freely axially in the aluminum alloy inner cylinder assembly (3) and cannot fall out of the coring drill bit (2).

3. A piston sealing device for closed coring in drilling according to claim 1, characterized in that: The sealing sleeve (4) is evenly distributed with straightening bosses on its circumference, and the straightening bosses play a straightening role on the coring inner tube; threaded holes are arranged in the straightening bosses to cooperate with the shear pins (5).

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