Slip connector of coiled tubing special for CO2 injection in oil field

Abstract

The invention discloses a special coiled tubing slip connector for CO2 injection in an oil field. The inner wall of a lower joint is hermetically connected with the outer wall of a coiled tubing, and the outer side of the lower joint is in threaded connection with a test plug; the lower end of the lower joint is in threaded connection with the upper end of the connector, the lower end of the connector is provided with a slip, a slip sleeve is arranged outside the slip, and the upper end of the slip sleeve is in threaded connection with the lower end of the connector; the inner wall of the slip is of a zigzag structure, the outer wall of the slip is of a conical structure, and the diameter of the upper end of the slip is large. The inner wall of the slip sleeve is correspondingly of a conical structure; an anchoring device is composed of a connecting body, a slip and a slip sleeve, and the slip can tightly grasp the outer surface of the coiled tubing by adjusting the thread stroke of the slip sleeve and the connecting body. The method improves the success rate of CO2 injection. The device is mainly used for a CO2 injection process of a continuous oil pipe, and can also be used for operations such as sand flushing, well washing, salvaging, drilling, milling and grinding and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield gas injection technology, and in particular relates to a special continuous oil pipe slip connector for oilfield CO2 injection. Background Art

[0002] With the decreasing oil resources and the increasing difficulty of exploitation, it is becoming more and more important to improve the recovery rate of oil fields. Among them, CO2 injection can effectively improve the recovery rate and extend the production period of oil fields. In the process of CO2 injection production, since the injected gas has a strong solubility and will produce acid corrosion production equipment, it is very important to prevent gas leakage during the CO2 injection production process. At present, continuous tubing CO2 injection has been carried out in oil fields one after another, and the slip connector matched with the continuous tubing plays a key role in the CO2 injection production process. There are many types of slip connectors currently produced, such as the slip connector outside the continuous tubing and the slip connector on the top of the continuous tubing. The above products have solved the connection problem with the continuous tubing well, and can be used for sand flushing, well washing, salvage, drilling, milling and other processes. However, the above products cannot meet the process requirements of CO2 injection, such as the corrosion resistance and gas sealing of the slip connector itself. Summary of the invention

[0003] The purpose of the present invention is to provide a special continuous oil pipe slip connector for oil field CO2, which solves the problems of corrosion protection, air sealing and sealing verification of the slip connector body.

[0004] The technical solution adopted by the present invention is a special continuous tubing slip connector for CO2 injection in oil fields, which comprises a lower joint, a connector and a slip sleeve from top to bottom;

[0005] A sealing ring is provided on the inner wall of the lower joint, a metal sealing ring is installed at the lower end of the lower joint, the sealing ring and the metal sealing ring are sealed and connected to the outer wall of the coiled tubing, and the outer side of the lower joint is threadedly connected to the test plug; the lower end of the lower joint is threadedly connected to the upper end of the connector, a slip is installed at the lower end of the connector, a slip sleeve is provided outside the slip, and the upper end of the slip sleeve is threadedly connected to the lower end of the connector;

[0006] The inner wall of the slip is provided with a serrated structure, and the outer wall of the slip is a conical structure with a large diameter at the upper end; the inner wall of the slip sleeve corresponds to a conical structure; the anchoring device composed of the connector, the slip and the slip sleeve enables the slip to grasp the outer surface of the continuous oil pipe by adjusting the thread stroke of the slip sleeve and the connector.

[0007] The present invention is also characterized in that:

[0008] The material of metal parts is 13Cr.

[0009] Airtight connection with coiled tubing threads.

[0010] The sealing ring is made of CO2 resistant rubber.

[0011] The metal seal is made of nickel alloy.

[0012] After the coiled tubing and the slip connector are inserted and docked, a pressure test can be carried out to verify their sealing performance.

[0013] The beneficial effects of the present invention are:

[0014] The present invention is used for the special continuous tubing slip connector for CO2 injection in oil fields. The stainless steel material and airtight connection method can effectively prevent the corrosion of the material and the leakage of the gas. After the continuous tubing and the slip connector are inserted and docked, a pressure test can be performed to prevent the slip connector from leaking during the CO2 injection process and ensure the sealing performance. The cooperation between the slip and the slip sleeve ensures the tensile strength of the slip connector. It is mainly used in the continuous tubing CO2 injection process, and can also be used for sand flushing, well washing, salvage, drilling, milling and other processes and other operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention is a structural schematic diagram of a special coiled tubing slip connector for oil field CO2 injection.

[0016] In the figure: 1. lower joint, 2. sealing ring, 3. test plug, 4. metal sealing ring, 5. connector, 6. slip, 7. slip sleeve, 8. continuous oil pipe. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The present invention is used for a special continuous tubing slip connector for CO2 injection in oil fields, such as Figure 1 As shown, it includes a lower joint 1, a sealing ring 2 is installed inside the lower joint 1, a test plug 3 is threadedly connected to the outer side of the lower joint 1, a metal sealing ring 4 is installed at the lower end of the lower joint 1, the lower joint 1 is threadedly connected to a connector 5, a cava 6 is installed at the lower end of the connector 5, and the connector 5 is threadedly connected to a cava sleeve 7.

[0019] The stainless steel material and airtight connection method of this device can effectively prevent gas corrosion to the material and gas leakage. After the coiled tubing 8 and the slip connector are inserted and docked, a pressure test can be performed to verify, and the slip connector leakage during the CO2 injection process can also be avoided to ensure the sealing performance. The cooperation between the slip and the slip sleeve ensures the tensile strength of the slip connector.

[0020] After the coiled tubing and the slip connector are inserted and docked, the slip sleeve 7 and the connector 5 are adjusted to make the slip 6 and the outer wall of the coiled tubing 8 bite into one.

[0021] The gap between the connector 5 and the lower joint 1 is adjusted so that the metal sealing ring 4 is closely attached to the outer wall of the coiled tubing to seal it.

[0022] Remove the test plug 3, install a connecting test pipeline here, and perform a pressure test on the metal sealing ring 4 and the sealing ring 2 to verify their sealing performance and prevent gas leakage.

[0023] The working principle of the special coiled tubing slip connector for CO2 injection in oil fields of the present invention is as follows:

[0024] The slip connector includes an anchoring device consisting of a connector 5, a slip 6, and a slip sleeve 7. A serrated structure is arranged inside the slip 6, and the inclination of the tapered structure on the outer surface of the slip 6 and the inclination of the tapered structure on the inner wall of the slip sleeve 7 are matched. The slip sleeve 7 is threadedly connected to the connector 5, and the slip 6 is made to grip the outer surface of the coiled tubing 8 by adjusting the thread stroke. At this time, the inclination of the outer surface of the slip 6 and the inclination of the inner wall of the slip sleeve 7 form a self-locking angle, which more firmly grips the outer wall of the coiled tubing to form an integral body, which is safe and reliable.

[0025] The sealing and testing device is composed of the lower joint 1 and the connector 5 connected by threads. After the coiled tubing 8 and the slip connector are inserted into the docking pull force, the metal sealing ring 4 is tightly attached to the outer wall of the coiled tubing 8 by adjusting the gap between the lower joint 1 and the connector 5 by threads to make it sealed. During the sealing test, the test plug 3 is removed, and the pressure test pipeline is installed here to test the sealing performance of the metal sealing ring 4 and the sealing ring 2 to prevent the slip connector from leaking during the CO2 injection process, ensure the sealing performance, and improve the success rate of CO2 injection.

Claims

1. A special coiled tubing slip connector for CO2 injection in oil fields, characterized by: It includes, from top to bottom, a lower joint (1), a connector (5) and a slip sleeve (7); The inner wall of the lower joint (1) is sealedly connected to the outer wall of the coiled tubing (8), and the outer side of the lower joint (1) is threadedly connected to the test plug (3); the lower end of the lower joint (1) is threadedly connected to the upper end of the connector (5), a slip (6) is installed at the lower end of the connector (5), a slip sleeve (7) is provided outside the slip (6), and the upper end of the slip sleeve (7) is threadedly connected to the lower end of the connector (5); The inner wall of the slip (6) is provided with a serrated structure, and the outer wall of the slip (6) is a conical structure with a large diameter at the upper end; the inner wall of the slip sleeve (7) corresponds to the conical structure; the anchoring device composed of the connector (5), the slip (6) and the slip sleeve (7) enables the slip (6) to grasp the outer surface of the coiled tubing (8) by adjusting the thread stroke of the slip sleeve (7) and the connector (5).

2. The special coiled tubing slip connector for oilfield CO2 injection according to claim 1 is characterized in that: The inner wall of the lower joint (1) is provided with a sealing ring (2), and the sealing ring (2) is sealedly connected to the outer wall of the continuous oil pipe (8).

3. The special coiled tubing slip connector for CO2 injection in oil fields according to claim 2 is characterized in that: A metal sealing ring (4) is installed at the lower end of the lower joint (1), and the metal sealing ring (4) is sealed and connected to the outer wall of the continuous oil pipe (8).

4. The special coiled tubing slip connector for oilfield CO2 injection according to claim 1, characterized in that: The outer side of the lower connector (1) is threadedly connected to the test plug (3).

5. The special coiled tubing slip connector for CO2 injection in oil fields according to claim 1, characterized in that: The lower joint (1) is connected to other downhole tools by an airtight buckle.

6. The special coiled tubing slip connector for CO2 injection in oil fields according to claim 1, characterized in that: The lower joint (1), the connector (5), the slip (6), and the slip sleeve (7) are all made of 13Cr.

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