Lining oil pipe connecting structure of airtight threaded oil pipe sealed through end face extrusion

Abstract

The utility model discloses a lining oil pipe connecting structure of an airtight threaded oil pipe sealed by end face extrusion, which relates to the technical field of lining pipes and comprises a lining pipe, an oil pipe body and a coupling, the oil pipe body and the coupling are connected through airtight threads sealed by end face extrusion, a pushing platform is arranged in the middle of the inner wall of the coupling, and the diameter of an inner hole of the pushing platform is consistent with that of an inner hole of the oil pipe. The lining pipe is fixedly inserted into the oil pipe body and an inner hole of the coupling pushing bearing platform; the end expansion pipe is used for fixing the lining pipe, the end expansion pipe is made of an anti-corrosion metal material and is fixedly inserted into the end of the lining pipe, and the outer wall of the end expansion pipe is tightly attached to the inner wall of the lining pipe; turnups attached to the end faces of the lining pipes are arranged at the outer ends of the end expansion pipes, and the turnups of the end expansion pipes of the two lining pipes in the coupling are attached together in a sealed mode. The turnup edges of the end expansion pipes of the two lining pipes in the coupling are attached together in a sealed mode, conveyed fluid is prevented from making contact with the oil pipe body and the coupling, and therefore the anti-corrosion effect of the oil pipe threaded connector is obviously improved.

Description

Technical Field

[0001] The utility model relates to the technical field of liner pipes, in particular to an liner oil pipe connection structure of an airtight threaded oil pipe sealed by end face extrusion. Background Art

[0002] As the difficulty of oil and gas reservoir development increases, the anti-corrosion problem of oil pipes has received more and more attention worldwide. Oil pipe corrosion and eccentric wear failure account for 80% of oil pipe failure accidents. Through the investigation of oil pipe string leakage and fracture accidents in various international oil fields, it was found that the failure position is mostly at the thread of the oil pipe joint near the neutral point of the oil pipe string. This place is very prone to stress fatigue fracture and is the most prone to accidents in the downhole oil pipe string. Solving the anti-corrosion problem at the threaded joints of the oil pipe is becoming increasingly urgent.

[0003] Ordinary lined oil pipes are generally covered with liner flanges. Ordinary flanges have the following problems: the liner flanges and the oil pipe body are hung, and they are not tightly combined. There is a gap between the liner and the oil pipe. After the liner is lowered into the well, it expands and elongates due to heat, and the flanges leave the end face of the oil pipe, which does not play a role in corrosion protection, and the conveying fluid can still contact the oil pipe body; some liner uses high temperature resistant liner materials that are not easy to flange; there are also liner flanges that are not strong enough to cause the liner flanges to break and the liner to expand and contract, and the liner fails to achieve the anti-corrosion effect on the oil pipe body. The special oil pipe gas seal connection oil pipe thread has special sealing requirements. The sealing is based on the end face compression seal. The connection between the oil pipe and the coupling is a cone straight surface. When the flange is directly flanged, it affects the push surface sealing, so the liner flange anti-corrosion technology cannot be used; in order to solve the anti-corrosion problem, the current oil pipe anti-corrosion also uses stainless steel materials to process and manufacture the oil pipe body and the oil pipe coupling. The cost of using stainless steel materials is very high, which greatly increases the production cost of oil and gas wells in oil fields. Utility Model Content

[0004] The utility model aims to solve the defects in the prior art and provides an inner liner oil pipe connection structure of an airtight threaded oil pipe which is sealed by end face extrusion.

[0005] The technical scheme of the utility model is: an inner liner oil pipe connection structure of an airtight threaded oil pipe sealed by end face extrusion, comprising an inner liner pipe and an oil pipe body and a coupling connected by airtight threads sealed by end face extrusion, a push bearing platform is provided in the middle of the inner wall of the coupling, the inner hole of the push bearing platform is consistent with the inner hole diameter of the oil pipe, the inner liner pipe is fixedly inserted in the inner hole of the oil pipe body and the coupling push bearing platform, and its outer diameter is adapted to the inner hole diameter of the oil pipe body and the coupling push bearing platform;

[0006] It also includes an end expansion tube for fixing the liner pipe, which is made of anti-corrosion metal and is fixedly inserted in the end of the liner pipe, with its outer wall tightly fitting against the inner wall of the liner pipe; the outer end of the end expansion tube is provided with a flange that fits against the end face of the liner pipe, and the flanges of the end expansion tubes of the two liner pipes in the coupling are sealed and fitted together.

[0007] Preferably, the outer end surface of the end expansion tube at one end of the liner tube is flush with the end surface of the push-bearing platform of the coupling, and the outer end surface of the end expansion tube at the other end is flush with the corresponding end surface of the oil pipe body.

[0008] Preferably, a plurality of annular protrusions are axially arranged on the tube wall of the end expansion tube for improving the connection firmness between the end expansion tube and the inner liner tube.

[0009] Compared with the prior art, the utility model has the following advantages:

[0010] The device fixes the liner pipe by expanding the end pipe, thus solving the problem that the flanged liner pipe cannot be sealed. Meanwhile, the flanged seals of the end expansion pipes of the two liner pipes in the coupling are fitted together, thus preventing the conveying fluid from contacting the oil pipe body and the coupling, thereby significantly improving the anti-corrosion effect at the threaded joint of the oil pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a structural schematic diagram of the utility model.

[0012] In the figure: 1, tubing body, 2, liner pipe, 3, end expansion pipe, 301, annular protrusion, 302, flange, 4, coupling, 401, push bearing platform. DETAILED DESCRIPTION

[0013] The utility model is further described below with reference to the accompanying drawings and embodiments. Embodiment 1

[0014] Reference Figure 1 As shown, an inner liner oil pipe connection structure of an airtight threaded oil pipe sealed by end face extrusion includes an inner liner pipe 2 and an oil pipe body 1 and a coupling 4 connected by airtight threads sealed by end face extrusion. A push support 401 is provided in the middle of the inner wall of the coupling 4. The inner hole of the push support 401 is consistent with the inner hole diameter of the oil pipe. The inner liner pipe 2 is fixedly inserted in the inner holes of the oil pipe body 1 and the push support 401 of the coupling 4, and its outer diameter is adapted to the inner hole diameters of the oil pipe body 1 and the push support 401 of the coupling 4.

[0015] It also includes an end expansion tube 3 for fixing the liner pipe 2. The end expansion tube 3 is made of anti-corrosion metal, and is fixedly inserted in the end of the liner pipe 2. Its outer wall is tightly fitted with the inner wall of the liner pipe 2. The outer end of the end expansion tube 3 is provided with a flange 302 that fits on the end face of the liner pipe 2, and the flanges 302 of the end expansion tubes 3 of the two liner pipes 2 are sealed together in the coupling 4.

[0016] During production, the two oil pipe bodies 1 are threadedly connected with the coupling 4 so that the end face of the oil pipe body 1 is squeezed onto the end face of the push support 401 of the coupling 4 to achieve end face extrusion sealing; then the end expansion tube 3 is inserted into the end of the liner tube 2 so that its flange 302 fits against the end face of the liner tube 2, and then the two liner tubes 2 carrying the end expansion tube 3 are inserted into the inner holes of the oil pipe body 1 and the push support 401 of the coupling 4, and the flanges 302 of the end expansion tubes 3 of the two liner tubes 2 in the coupling 4 are sealed and fit together; finally, the end expansion tube 3 is expanded by a tube expander so that its outer wall fits tightly against the inner wall of the liner tube 2.

[0017] This device fixes the liner pipe 2 through the end expansion tube 3, which solves the problem that the flange 302 of the liner pipe 2 cannot be used for sealing. At the same time, the flanges 302 of the end expansion tubes 3 of the two liner pipes 2 in the coupling 4 are sealed together, avoiding the conveying fluid from contacting the oil pipe body 1 and the coupling 4, thereby significantly improving the anti-corrosion effect at the oil pipe threaded joint. Embodiment 2

[0018] In this embodiment, the outer end surface of the end expansion tube 3 at one end of the liner tube 2 is flush with the end surface of the push support platform 401 of the coupling 4, and the outer end surface of the end expansion tube 3 at the other end is flush with the corresponding end surface of the oil pipe body 1. Embodiment 3

[0019] On the basis of the first embodiment, in order to improve the connection firmness between the end expansion tube 3 and the inner liner tube 2, this embodiment provides a plurality of annular protrusions 301 along the axial direction on the tube wall of the end expansion tube 3. This can increase the friction surface between the end expansion tube 3 and the inner liner tube 2 and improve the connection.

[0020] The present invention is not limited to the above-mentioned implementation modes. Within the knowledge scope of those skilled in the art, various changes can be made without departing from the purpose of the present invention. The changed contents still belong to the protection scope of the present invention.

Claims

1. A liner oil pipe connection structure of an airtight threaded oil pipe sealed by end face extrusion, comprising an inner liner pipe, an oil pipe body and a coupling connected by airtight threads sealed by end face extrusion, a push bearing platform is provided in the middle of the inner wall of the coupling, and the inner hole of the push bearing platform has the same diameter as the inner hole of the oil pipe, and is characterized by: The inner liner is fixedly inserted into the inner holes of the tubing body and the coupling support, and its outer diameter matches the inner hole diameters of the tubing body and the coupling support; It also includes an end expansion tube for fixing the liner pipe, which is made of anti-corrosion metal and is fixedly inserted in the end of the liner pipe, and its outer wall fits tightly with the inner wall of the liner pipe; the outer end of the end expansion tube is provided with a flange that fits on the end face of the liner pipe, and the flanges of the end expansion tubes of the two liner pipes in the coupling are sealed and fit together.

2. The inner liner oil pipe connection structure of the gas-tight threaded oil pipe sealed by end face extrusion according to claim 1 is characterized in that: The outer end surface of the end expansion tube at one end of the liner tube is flush with the end surface of the push bearing platform of the coupling, and the outer end surface of the end expansion tube at the other end is flush with the corresponding end surface of the oil pipe body.

3. The inner liner oil pipe connection structure of the gas-tight threaded oil pipe sealed by end face extrusion according to claim 1 is characterized in that: A plurality of annular protrusions for improving the connection firmness between the end expansion tube and the inner liner tube are axially arranged on the tube wall of the end expansion tube.

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