CN113833918A

CN113833918A - Lining structure of high-pressure water injection composite pipeline in oil field

Info

Publication number: CN113833918A
Application number: CN202110992641.XA
Authority: CN
Inventors: 龙连春; 吴雨泽; 吴奇
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2021-08-27
Filing date: 2021-08-27
Publication date: 2021-12-24

Abstract

The invention discloses an inner lining structure for an oil field ground water injection composite pipeline, which mainly consists of a steel pipe line, a necked butt welded concave flange, an inner lining pipe, a flanged inner lining, a limit ring, a polytetrafluoroethylene sealing ring and bolts It is composed of fasteners, in which the inner lining pipe with an outer diameter slightly larger than the inner wall of the steel pipe is embedded in the inner wall of the steel pipe by the equal diameter compression technology, and the lining at the joint is compressed into a flange shape by a high temperature compression device, and the same belt neck butt welding method The blue end face fits tightly. The thickness of the flanged lining is smaller than the depth of the flange groove, and the PTFE sealing ring is embedded in the groove to ensure that the lining and the sealing ring are pressed and sealed together under the action of the bolt pre-tightening force. Finally, one end of the limit ring is welded to the end face of the flange. Under the action of the bolt pre-tightening force, the other end of the limit ring is fitted with the flange end face on the other side, and the lining connection structure is locked, positioned and sealed. The overall mechanical performance of the pipeline is greatly improved, the economic cost is reduced, and the problem of environmental pollution is solved.

Description

Lining structure of high-pressure water injection composite pipeline in oil field

Technical Field

The invention relates to a lining connection anticorrosion structure for a high-pressure water injection ground pipeline in an oil field, which can effectively solve the problem of water inflow of a lining and a steel pipe interlayer, greatly improve the anticorrosion performance and the pressure resistance of the pipeline and provide reference for the application of a composite pipeline in practical engineering.

Background

After the oil field is put into development, the energy of the oil layer is continuously consumed along with the increase of the exploitation time, so that the pressure of the oil layer is continuously reduced, underground crude oil is greatly degassed, the viscosity is increased, the yield of the oil well is greatly reduced, even the injection and production stop can be realized, and a large amount of underground residual dead oil cannot be extracted. In order to make up for the underground deficit caused by the production of crude oil, maintain or improve the pressure of an oil layer, realize high and stable yield of an oil field and obtain higher recovery ratio, water must be injected into the oil field.

A ground pipeline for carrying oil field water injection generally adopts the steel and does not have interior tubular product of preventing, has the perforation problem of corruption, causes very big influence to production, can cause environmental pollution simultaneously. The corrosion prevention and joint coating technology in the water injection pipeline has the problems of no erosion resistance, no pressure resistance, easy brittle fracture, pinhole effect, difficult control of construction quality, high cost and the like. Therefore, the lining inserting technology is adopted to embed the lining with high strength, low density, high wear resistance, long service life and corrosion resistance into the single steel pipe to form a structural composite pipe with the steel pipe, the external steel pipe plays a role in bearing pressure, and the lining pipe plays roles in internal corrosion resistance, wear resistance and the like.

The lining strength in the composite pipeline is low, in a high-pressure flow transmission pipeline, the vibration damage at the joint of the composite pipeline is most obvious due to unstable pressure or unstable flow speed, and the lining structure at the joint needs to have sufficient strength and tightness in the practical application process.

Disclosure of Invention

In order to ensure that the lining joint of the high-pressure water injection composite pipeline has better sealing property and strength, the invention designs a lining sealing structure for the connection of a high-pressure water injection flange of an oil field. The problem of inside lining, steel pipe intermediate layer intake is solved, the corrosion resisting property and the compressive capacity of pipeline have been improved greatly, economic cost has been reduced, environmental pollution has been reduced, the life of whole pipeline has been improved.

The design structure mainly comprises a steel pipeline 1, a neck butt welding concave flange 2, an inner lining pipe 3, a flanging lining 4, a limiting ring 5, a sealing ring 6 and a bolt fastener 7. Both side parts of the steel pipeline 1 are fixed by neck butt welding concave flanges 2, the inner walls of the steel pipeline 1 and the neck butt welding concave flanges 2 are lining pipes 3, and the two neck butt welding concave flanges 2 are connected through a flanging lining 4; the end part of the flanging lining 4 is provided with a limiting ring 5 and is installed and fixed by a sealing ring 6 and a bolt fastener 7.

The steel pipeline 1 and the neck butt welding flange 2 are made of 20# steel, the lining pipe 3 and the flanging lining 4 are made of ultra-high molecular weight polyethylene (UHMWPE) with high strength, low density and excellent corrosion resistance, the limiting ring is made of A106 tubular products or customized forgings, and the sealing ring is made of polytetrafluoroethylene with excellent sealing performance.

The steel pipeline 1 is connected with a neck butt welding concave flange 2 in a welding mode, an UHMWPE lining pipe 3 with the diameter slightly larger than the inner wall of the steel pipe is temporarily reduced and pulled in by a tractor, a section of length is reserved at the end part of the lining pipe, the lining pipe is pressed into a flange shape by a special high-temperature pressing device, and the flange and the steel flange form a composite flange.

The neck butt welding concave flange 2 adopts the concave surface to carry out sealing connection, and the concave surface thickness is big than turn-ups inside lining 4 thickness, with 6 imbeds the concave surface of polytetrafluoroethylene sealing ring, with the common pressure-bearing of inside lining. The diameter of the concave surface is slightly larger than that of the turned-over edge lining 4, so that stress concentration cannot occur in the pressing process, and the lining is prevented from being crushed.

The polytetrafluoroethylene sealing element is made into a ring shape, the outer diameter of the polytetrafluoroethylene sealing ring 6 is slightly smaller than the diameter of the concave surface of the neck butt welding flange 2, and stress concentration cannot be caused under the action of bolt pre-tightening force. The inner diameter of the sealing ring 6 is the same as that of the lining pipe 3.

The inner diameter of the limiting ring 5 is 1-2 mm larger than the outer diameter of the polytetrafluoroethylene sealing ring, and sliding is avoided in the pressing process. The thickness of the limiting ring is slightly smaller than that of the exposed part of the polytetrafluoroethylene, so that after the liner and the sealing ring are compressed and deformed, the other end of the limiting ring 5 is compressed with the flange on the other side, and the positioning and locking functions are achieved.

The integral composite pipeline is good in integrity, and the lining structure at the joint has good sealing performance and meets the connection requirement.

Drawings

FIG. 1 is a cross-sectional view of a composite pipeline in elevation

Fig. 2 is a right side view of the composite pipeline.

FIG. 3 is a cross-sectional view in elevation of the liner tube.

FIG. 4 is a front view of a polytetrafluoroethylene sealing ring.

FIG. 5 is a front view of the stop collar.

In the figure: 1. the steel-pipe line, 2, take neck butt welding concave flange, 3, inside lining pipe, 4, turn-ups inside lining, 5, spacing ring, 6, sealed dish, 7, bolt fastener.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

As shown in figure 1, the lining structure at the joint of the high-pressure water injection composite pipeline in the oil field comprises a steel pipeline 1, a neck-butt-welding concave flange 2, a lining pipe 3, a flanging lining 4, a limiting ring 5, a sealing ring 6 and a bolt fastener 7. The steel pipeline 1 is welded with the welding flange 2 with the neck, the outer diameter of the flanging lining 4 is larger than the inner diameter of the steel pipeline 1, an isometric compressor is adopted, the diameter of the lining pipe 2 is temporarily reduced, the lining pipe 3 is pulled into the pipe by a tractor, and the steel pipeline is pressed or attached to the inner wall of the steel pipe by depending on the self-resilience characteristic.

As shown in the combined

drawings

1 and 3, the flanging thickness of the joint of the lining pipe is slightly smaller than the depth of the concave flange, the polytetrafluoroethylene sealing ring 6 is embedded into the concave flange, the flanging lining and the polytetrafluoroethylene sealing ring are guaranteed to bear pressure and seal together under the action of the pre-tightening force of the bolt, and the sealing performance is guaranteed.

As shown in figure 4, the polytetrafluoroethylene 6 is made into a ring shape, the outer diameter of the sealing ring is 2-3 mm smaller than that of the concave surface, and the pressing deformation process is guaranteed not to be crushed.

As shown in figures 1, 2 and 5, one end of the limiting ring 5 is welded with the end face of the concave flange, and the inner diameter of the limiting ring 5 is 1-2 mm larger than the outer diameter of the polytetrafluoroethylene sealing ring, so that slippage is avoided in the pressing process. The thickness of the limiting ring is slightly smaller than that of the exposed part of the polytetrafluoroethylene, so that after the liner and the sealing ring are compressed and deformed, the other end of the limiting ring 5 is compressed with the flange on the other side, and the positioning and locking functions are achieved.

The technical principle of lining penetration is as follows: the UHMWPE lining is embedded into a single steel pipeline by adopting a process of inserting an ultrahigh molecular weight polyethylene (UHMWPE) pipe. The UHMWPE pipe has excellent chemical stability, corrosion resistance, wear resistance, temperature resistance, long service life, ultralow friction resistance and the like, and the inner wall of the UHMWPE pipe is smooth, is not easy to scale, is nontoxic and does not breed bacteria. The method comprises the following steps: the method comprises the steps of selecting a proper lining UHMWPE pipe 3, reducing the diameter of the pipe, pulling the pipe into a steel pipeline 1 under the action of certain traction force, and enabling the lining pipe 3 to recover the original physical form under the action of certain external force by adopting a special technology to be tightly attached to the inner wall of an outer steel pipe to form a pipe-in-pipe structure. And a special high-temperature pressing device is adopted to compress the redundant lining pipe into a flange shape, the flange shape is tightly attached to the concave surface of the welding flange with the neck, and the flanging lining 4 and the polytetrafluoroethylene sealing ring 6 are jointly pressed and sealed under the action of the pretightening force of the bolt. The limiting ring locks the exposed part of the polytetrafluoroethylene sealing ring 6 to ensure that the polytetrafluoroethylene sealing ring does not slide. The composite pipeline structure has the comprehensive performance of a steel pipe and an UHMWPE pipe, has good strength, sealing performance and structural stability, and greatly prolongs the service life of a pipeline.

Claims

1. The oilfield high pressure water injection composite pipeline lining structure is characterized in that: a steel pipe line (1), a necked butt welded concave flange (2), a lining pipe (3), a flanged lining (4), a limit The ring (5), the sealing ring (6) and the bolt fastener (7) are composed; both sides of the steel pipe line (1) are fixed by necked butt welded concave flanges (2), and the steel pipe line (1) and The inner wall of the necked butt welded concave flange (2) is a lining pipe (3), and the two necked butt welded concave flanges (2) are connected by a flanged inner lining (4); The end of the lining (4) is provided with a limit ring (5), which is installed and fixed by a sealing ring (6) and a bolt fastener (7).

2. The oilfield high pressure water injection composite pipeline lining structure according to claim 1, characterized in that: the steel pipe line (1) and the necked butt welding concave flange (2) are all made of 20# steel, and the lining pipe (3) The inner lining (4) and the flanging are made of ultra-high molecular weight polyethylene, the limit ring (5) is made of A106 pipe material or customized forgings, and the sealing ring is made of polytetrafluoroethylene with excellent sealing performance.

3. The oilfield high pressure water injection composite pipeline lining structure according to claim 1 is characterized in that: the steel pipe line (1) and the necked butt welded concave flange (2) are connected by welding, and the diameter is slightly larger than the inner wall of the steel pipe. The inner liner (3) of the lining tube (3) is temporarily shrunk, and is pulled in by a tractor.

4. The oilfield high-pressure water injection composite pipeline lining structure according to claim 1, characterized in that: the necked butt welded concave flange (2) adopts a concave surface for sealing connection, and the thickness of the concave surface is larger than that of the flanged lining (4) , the sealing ring (6) is embedded in the concave surface, and bears pressure together with the inner lining; the diameter of the concave surface is larger than the diameter of the flanged inner lining (4).

5. The oilfield high pressure water injection composite pipeline lining structure according to claim 1, characterized in that: the outer diameter of the sealing ring (6) is smaller than the concave diameter of the necked butt welded concave flange (2); the inner diameter of the sealing ring (6) is the same as The inner diameter of the inner liner (3) is the same.

6. The oilfield high pressure water injection composite pipeline lining structure according to claim 1, characterized in that: the inner diameter of the limit ring (5) is 1-2mm larger than the outer diameter of the polytetrafluoroethylene sealing ring; the thickness of the limit ring is smaller than that of the polytetrafluoroethylene Exposed parts of vinyl fluoride.

7. The oilfield high-pressure water-injection composite pipeline lining structure according to claim 1, characterized in that: under the high-pressure water-injection situation, it is ensured that the flanged lining (4) is the same as the PTFE sealing ring under the action of the bolt pre-tightening force (6) Press it tightly, and the limit ring will lock it.

8. The oilfield high pressure water injection composite pipeline lining structure according to claim 1, characterized in that: the ultra-high molecular weight polyethylene lining pipe (3) is pulled into the steel pipe under the action of the tractor, and the pressure is applied It is tightly attached to the inner wall of the pipeline by means of the method, the diameter of the flanging lining is smaller than the diameter of the concave flange, and the thickness of the flanging is smaller than the thickness of the concave flange.