A gas-liquid double-stream injection tool

Abstract

The present invention provides a gas-liquid dual-flow injection tool with a short axial dimension and capable of quickly replacing vulnerable sealing components for a gas-liquid dual-flow drilling process, which includes a main shaft, a locking sleeve, a central pipe, a bolt group, a sealing nest body, an internal gas injection housing, bearings, rotary seals, gas injection static seals, elbow pipes, a union joint, etc. The central pipe inside the main shaft is used for transmitting drilling fluid. There are two through gas injection holes on the side of the middle part of the main shaft, forming an upper single-input and lower double-output flow channel structure with the central pipe through the annulus between the main shaft and the central pipe. The outer side of the main shaft is a rotation gas injection assembly symmetrically arranged up and down. The outermost side of the assembly is a gas injection housing, and in the middle are two sealing nest bodies symmetrically distributed up and down. One end of the sealing nest body uses a Gleitring to achieve rotary sealing with the main shaft, and one end uses angular contact ball bearings to achieve rotary connection with the main shaft. The upper and lower sealing nest bodies and the gas injection holes on the main shaft jointly form a rotary sealing gas injection channel.

Description

Technical Field

[0001] The present invention relates to a wellhead supporting tool for gas-liquid dual-flow drilling technology in the field of oil and gas exploration and development drilling engineering, and particularly relates to a gas-liquid dual-flow injection tool. Background Art

[0002] During the process of establishing a wellbore in oil and gas exploration and development, for hard formations without water production, severely lost circulation formations, severely water-deficient formations, and formations with low formation pressure and clear distribution patterns, using gas-liquid dual-flow drilling is an economical and efficient technical option. Gas-liquid dual-flow drilling is achieved by using double-wall drill pipes (i.e., drill pipes with two concentric metal tubes having two flow channels). While injecting drilling circulating fluid into the bit from the inner annulus of the double-wall drill pipe, high-pressure gas is injected into the annulus between the drill string and the wellbore at an appropriate position of the drill string from the outer annulus of the double-wall drill pipe. The high-pressure gas mixes with the drilling fluid to greatly reduce the density of the drilling fluid, thereby effectively controlling the bottom hole pressure and implementing the underbalanced drilling operation, and finally efficiently establishing the wellbore.

[0003] A key tool for gas-liquid dual-flow drilling is the gas-liquid dual-flow injection tool located at the wellhead position on the drill floor. It is connected to the kelly or top drive at the upper end, connected to the double-wall drill pipe at the lower end, and the high-pressure gas injection pipeline is connected to the side. The gas-liquid dual-flow injector includes a mandrel, a gas distribution assembly, bearings, and a sealing assembly, etc. The mandrel can rotate with the drill string, and the gas distribution assembly can rotate relative to the drill string through components such as bearings and sealing assemblies and can input high-pressure gas, among which the sealing assembly belongs to a vulnerable part. The existing gas-liquid dual-flow injectors have the deficiencies of poor sealing reliability, the sealing assembly cannot be replaced on-site, the maintenance tools take a long time to occupy the operation time, and at the same time, the overall axial dimension of the tool is relatively long, resulting in a high position for wellhead disassembly operations and poor wellhead operation efficiency. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a gas-liquid dual-flow injection tool with a short axial dimension and quick replaceable seals for the gas-liquid dual-flow drilling process in view of the deficiencies of the prior art, so as to improve the operation efficiency and the reliability of the gas-liquid injection tool.

[0005] To achieve the above object, the technical solution adopted by the present invention to solve its technical problems is:

[0006] A gas-liquid double-flow injection tool, comprising a main shaft 1, a central tube 3, a gas distribution assembly and a bearing 11; wherein: the main shaft 1 is a hollow rotating cylinder, with an upper joint provided at the upper end. Inside the lower part of the upper joint, a locking buckle 102 and a stepped structure 103 are arranged in sequence from top to bottom. A lower joint is provided at the lower end. A through gas injection hole 107 is arranged in the middle of the main shaft 1 in the direction perpendicular to the axis; the upper end of the central tube 3 is seated on the stepped structure of the main shaft 1 and is locked by a locking sleeve 2. The part of the central tube 3 below the gas injection hole 107 of the main shaft 1 is an outer reduced-diameter structure. A single upper input and double lower output flow channel structure is formed between the central tube 3 and the main shaft 1; the gas distribution assembly is rotationally sealed outside the gas injection hole 107 of the main shaft 1 through the bearing 11.

[0007] Furthermore:

[0008] The gas distribution assembly includes a sealing nest body 5, an air injection housing 7, a rotary seal 12 and a bent pipe 14; the sealing nest body 5 is a hollow rotating body, the lower part is disc-shaped, the upper part is sleeve-shaped, and a rotary seal groove 501 for cooperating with the rotary seal 12 is arranged inside. The outer diameter of the upper end of the sealing nest body 5 is smaller and the inner diameter is larger than that of the lower end. The inner side of the lower end is a bearing mounting surface 504 for cooperating with the bearing 11, the outer side is a housing mounting surface 503, and a plurality of bolt holes 505 are evenly distributed on the outer side of the disc-shaped rotating body parallel to the axis; the air injection housing 7 is a sleeve-shaped body, and a plurality of threaded holes 701 are evenly distributed on both the upper and lower end faces. A stepped through hole with a cross-section is arranged on one side in the middle. The inner side of the through hole is an air injection channel 702, and the outer side is connected and cooperated with the bent pipe 14.

[0009] Rotary gas sealing surfaces 106, bearing cylindrical surfaces 105 and grease sealing surfaces 104 are symmetrically arranged in sequence on both sides of the gas injection hole 107 of the main shaft 1; a static seal groove 502 is arranged on the outer side of the upper end of the sleeve-shaped body of the sealing nest body 5, two rotary seal grooves 501 are arranged inside, and a grease sealing groove 507 and an oil cup hole 506 are also arranged on the inner side surface of the lower end; the outer side of the through hole of the air injection housing 7 is a bent pipe welding hole 703, and on both sides of the gas injection hole inside the housing, a rotary seal surface 704 and a static seal surface 705 are arranged in sequence.

[0010] An air injection static seal 13 is also arranged at the static seal surface 705 between the outer side of the sealing nest body 5 and the air injection housing 7.

[0011] An inner adjusting ring 6 and an outer adjusting ring 8 are respectively arranged inside and outside the bearing 11 between the main shaft 1 and the sealing nest body 5.

[0012] A core tube seal 9 is provided at the place where the central tube 3 is seated on the main shaft 1.

[0013] The usage process of the gas-liquid two-phase injection tool of the present invention is as follows: The tool is connected to the kelly or top drive at the upper part, connected to the double-wall drill pipe at the lower part, and connected to the high-pressure gas injection pipeline at the side. The drilling fluid input by the mud pump is injected into the inner annulus of the double-wall drill pipe through the central pipe. The high-pressure gas enters through the gas injection hole of the tool and enters the outer annulus of the double-wall drill pipe through the annulus between the main shaft and the central pipe. During drilling, the main shaft part rotates with the drill string, and the rotating gas injection assembly is relatively stationary. When replacing the sealing assembly regularly, the connecting bolts of the upper and lower sealing nests are removed respectively, the sealing nests are taken out, the corresponding seals are replaced and then installed into the tool.

[0014] The present invention has the following beneficial effects:

[0015] 1. The axial dimension of the gas-liquid two-phase injection tool is short. During the process of connecting the drill string, the height and working space of the wellhead disassembly operation are appropriate, and there is no need to change the original operation procedure.

[0016] 2. The gas-liquid two-phase injection tool can quickly replace the vulnerable sealing assembly on-site, significantly improving the operation efficiency of gas-liquid two-phase operation and the reliability of gas-liquid injection. Description of the Drawings

[0017] Figure 1 is the overall structural schematic diagram of the present invention.

[0018] Figure 2 is Figure 1 the structural diagram of the key part, the main shaft 1 in

[0019] Figure 3 is Figure 1 the structural diagram of the key part, the sealing nest 5 in

[0020] Figure 4 is Figure 1 the structural diagram of the key part, the gas injection housing 7 in

[0021] In the figure: main shaft 1, locking sleeve 2, central pipe 3, bolt group 4, sealing nest 5, inner adjustment ring 6, gas injection housing 7, outer adjustment ring 8, core pipe seal 9, grease nipple 10, bearing 11, rotary seal 12, gas injection static seal 13, elbow 14, swivel 15, grease seal 16, inner drill pipe thread 101, locking buckle 102, step structure 103, outer drill pipe thread 108, gas injection hole 107, rotary gas sealing surface 106, bearing cylindrical surface 105, grease sealing surface 104, rotary seal groove 501, static seal groove 502, bearing installation surface 503, housing installation 504, bolt hole 505, grease seal groove 507, oil cup hole 506, threaded hole 701, gas injection channel 702, elbow welding hole 703, rotary sealing surface 704, static sealing surface 705. Detailed Embodiments

[0022] The present invention will be further described below in conjunction with the drawings and embodiments.

[0023] Example 1

[0024] A gas-liquid double-flow injection tool includes a main shaft 1, a central tube 3, a gas distribution assembly and a bearing 11; wherein: the main shaft 1 is a hollow rotating cylinder, with an upper joint at the upper end. Inside the lower part of the upper joint, a locking buckle 102 and a stepped structure 103 are arranged in sequence from top to bottom. A lower joint is provided at the lower end. A through gas injection hole 107 is arranged in the middle of the main shaft 1 in the direction perpendicular to the axis; the upper end of the central tube 3 is seated on the stepped structure of the main shaft 1 and is locked by a locking sleeve 2. The part of the central tube 3 below the gas injection hole 107 of the main shaft 1 is an outer reduced-diameter structure, and a single-input and double-output flow channel structure is formed between the central tube 3 and the main shaft 1; the gas distribution assembly is rotationally sealed outside the periphery of the gas injection hole 107 of the main shaft 1 through the bearing 11.

[0025] Example 2

[0026] On the basis of Example 1, the gas distribution assembly includes a sealing nest body 5, a gas injection housing 7, a rotary seal 12 and a bent pipe 14; the sealing nest body 5 is a hollow rotating body, the lower part is disc-shaped, the upper part is sleeve-shaped, and a rotary seal groove 501 for cooperating with the rotary seal 12 is arranged inside. The outer diameter of the upper end of the sealing nest body 5 is smaller and the inner diameter is larger than that of the lower end. The inner side of the lower end is a bearing mounting surface 504 for cooperating with the bearing 11, the outer side is a housing mounting surface 503, and a plurality of bolt holes 505 are evenly distributed on the outer side of the disc-shaped rotating body parallel to the axis; the gas injection housing 7 is a sleeve-shaped body, and a plurality of threaded holes 701 are evenly distributed on both the upper and lower end faces. One stepped through hole is arranged on one side in the middle. The inner side of the through hole is a gas injection channel 702, and the outer side is connected and cooperated with the bent pipe 14.

[0027] Further, on both sides of the gas injection hole 107 of the main shaft 1, a rotary gas sealing surface 106, a bearing cylindrical surface 105 and a grease sealing surface 104 are symmetrically arranged in sequence; on the outer side of the upper end of the sleeve-shaped body of the sealing nest body 5, one static seal groove 502 is arranged, and two rotary seal grooves 501 are arranged inside. A grease sealing groove 507 and an oil cup hole 506 are also arranged on the inner side surface of the lower end; the outer side of the through hole of the gas injection housing 7 is a bent pipe welding hole 703, and on both sides of the gas injection hole inside the housing, a rotary sealing surface 704 and a static sealing surface 705 are arranged in sequence.

[0028] Furthermore, a gas injection static seal 13 is also arranged at the static sealing surface 705 between the outer side of the sealing nest body 5 and the gas injection housing 7. An inner adjusting ring 6 and an outer adjusting ring 8 are respectively arranged inside and outside the bearing 11 between the main shaft 1 and the sealing nest body 5. A core tube seal 9 is provided at the position where the central tube 3 is seated on the main shaft 1.

[0029] Typical Example 3

[0030] Such as Figure 1As shown in the figure, a gas-liquid double-flow injection tool includes a main shaft 1, a locking sleeve 2, a central tube 3, a bolt group 4, a sealing nest 5, an inner adjustment ring 6, an air injection housing 7, an outer adjustment ring 8, a core tube seal 9, a grease nipple 10, a bearing 11, a rotary seal 12, an air injection static seal 13, a bent pipe 14, a union 15, and a grease seal 16. Among them:

[0031] At the axial center of the main shaft 1 is the central tube 3, which is used to transmit drilling fluid. The upper end of the central tube 3 is sealed with an O-ring seat on the step structure of the main shaft 1 and locked by the locking sleeve 2. There are two through air injection holes on the side of the middle part of the main shaft 1, forming an upper single-input and lower double-output flow channel structure with the central tube 3 through the annulus between the main shaft 1 and the central tube 3. The outside of the main shaft 1 is a rotation air injection assembly symmetrically arranged up and down. The outermost part of the assembly is the air injection housing 7, and in the middle are two sealing nests 5 symmetrically distributed up and down. A rotary seal is arranged inside the sealing nest 5, a static seal is arranged outside, and a grease seal is arranged on the end face. The air injection housing 7 and the sealing nest 5 are sealed with an O-ring and fixedly connected by the bolt group 4. One end of the sealing nest 5 uses a Gleason ring to achieve rotary sealing with the main shaft 1, and one end uses an angular contact ball bearing 11 to achieve rotary connection with the main shaft 1. The upper and lower sealing nests 5 and the air injection holes of the main shaft 1 together form a rotary seal air injection channel. A through hole is arranged on one side of the outside of the air injection housing 7, and an air injection bent pipe 14 is welded at the corresponding position. The free end of the bent pipe 14 is a union 15 interface.

[0032] As Figure 2 shown, the main shaft 1 is a hollow rotary cylinder, bearing axial load. Inside the upper end, an internal drill pipe thread 101, a locking thread 102, and a step structure 103 are arranged in sequence from top to bottom for connecting the central tube. The outside of the lower end is an external drill pipe thread 108. There is a through air injection hole 107 in the middle part of the main shaft 1 in the direction perpendicular to the axis. On both sides of the air injection hole 107, a rotary air seal surface 106, a bearing cylindrical surface 105, and a grease seal surface 104 are arranged symmetrically in sequence.

[0033] As Figure 3 shown, the sealing nest 5 is a hollow rotary body. The lower end is disc-shaped, and the upper end is sleeve-shaped. One static seal groove 502 is arranged on the outside of the upper end of the sleeve-shaped body, and two rotary seal grooves 501 are arranged inside. The upper end has a smaller outer diameter and a larger inner diameter than the lower end. The inside of the lower end is a bearing mounting surface 504, and the outside is a housing mounting surface 503. A plurality of bolt holes 505 are evenly distributed parallel to the axis on the outside of the disc-shaped rotary body, and a grease seal groove 507 and an oil cup hole 506 are arranged on the inner side.

[0034] As Figure 4 shown, the air injection housing 7 is a sleeve-shaped body. A plurality of threaded holes 701 are evenly distributed on both the upper and lower end faces. One through hole with a stepped cross-section is arranged on one side in the middle. The inside of the hole is an air injection channel 702, and the outside is a bent pipe welding hole 703. On both sides of the air injection hole inside the housing, a rotary seal surface 704 and a static seal surface 705 are arranged in sequence.

[0035] A gas-liquid double-flow injection tool mentioned in the present invention has the following usage process: The tool is connected to a kelly or a top drive at the upper part, a dual-wall drill pipe at the lower part, and a high-pressure gas injection pipeline at the side. The drilling fluid input by a mud pump is injected into the inner annulus of the dual-wall drill pipe through a central pipe 3. High-pressure gas enters through an injection hole 107 of the tool and enters the outer annulus of the dual-wall drill pipe through the annulus between a main shaft 1 and the central pipe 3. During drilling, the main shaft 7 rotates together with the drill string, and the rotating gas injection assembly is relatively stationary. When the sealing assembly is replaced regularly, the connecting bolts 4 of the upper and lower sealing nests 5 are removed respectively, the sealing nests 5 are taken out, the corresponding rotary seals 12 and grease seals 16 are replaced, and then they are installed into the tool.

Claims

1. A gas-liquid double-flow injection tool, comprising a main shaft (1), a central tube (3), a gas distribution assembly and a bearing (11); Characterized in that: The main shaft (1) is a hollow rotating cylinder, with an upper joint at the upper end. Inside the lower part of the upper joint, a locking buckle (102) and a stepped structure (103) are arranged in sequence from top to bottom. A lower joint is provided at the lower end. A through gas injection hole (107) is arranged in the middle of the main shaft (1) in the direction perpendicular to the axis; The upper end of the central tube (3) is seated on the stepped structure of the main shaft (1) and is locked by a locking sleeve (2). The part of the central tube (3) below the gas injection hole (107) of the main shaft (1) is an outer reduced-diameter structure, and a single upper input and double lower output flow channel structure is formed between the central tube (3) and the main shaft (1); The gas distribution assembly is rotationally sealed outside the periphery of the gas injection hole (107) of the main shaft (1) through a bearing (11); The gas distribution assembly includes a sealing nest body (5), a gas injection housing (7), a rotary seal (12) and a bent pipe (14); The sealing nest body (5) is a hollow rotating body, with a disc shape at the lower part and a sleeve shape at the upper part. A rotary seal groove (501) for cooperating with the rotary seal (12) is arranged inside. The outer diameter of the upper end of the sealing nest body (5) is smaller and the inner diameter is larger than that of the lower end. The inner side of the lower end is a bearing mounting surface (504) for cooperating with the bearing (11), and the outer side is a housing mounting surface (503). A plurality of bolt holes (505) are evenly distributed on the outer side of the disc-shaped rotating body parallel to the axis; The gas injection housing (7) is a sleeve-shaped body, with a plurality of threaded holes (701) evenly distributed on the upper and lower end faces. A stepped through hole with a single cross-section is arranged on one side in the middle. The inner side of the through hole is a gas injection channel (702), and the outer side is connected and cooperated with the bent pipe (14).

2. The gas-liquid double-flow injection tool according to claim 1, Characterized in that: Rotary gas sealing surfaces (106), bearing cylindrical surfaces (105) and grease sealing surfaces (104) are symmetrically arranged in sequence on both sides of the gas injection hole (107) of the main shaft (1); A static seal groove (502) is arranged on the outer side of the upper end of the sleeve-shaped body of the sealing nest body (5), and two rotary seal grooves (501) are arranged inside. A grease sealing groove (507) and an oil cup hole (506) are also arranged on the inner side of the lower end face; The outer side of the through hole of the gas injection housing (7) is a bent pipe welding hole (703). On both sides of the gas injection hole inside the housing, a rotary seal surface (704) and a static seal surface (705) are arranged in sequence.

3. The gas-liquid double-flow injection tool according to claim 2, Characterized in that: At A gas injection static seal (13) is also arranged at the static seal surface (705) between the outer side of the sealing nest body (5) and the gas injection housing (7).

4. The gas-liquid double-flow injection tool according to claim 1 or 2, 3, Characterized in that: An inner adjusting ring (6) and an outer adjusting ring (8) are respectively arranged inside and outside the bearing (11) between the main shaft (1) and the sealing nest body (5).

5. The gas-liquid double-flow injection tool according to claim 4, Characterized in that: A core tube seal (9) is provided at the position where the central tube (3) is seated on the main shaft (1).

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