Continuous oil tube with gradually changed wall thickness and manufacturing method thereof

Abstract

The invention relates to a continuous oil tube with a gradually changed wall thickness and a manufacturing method thereof; the continuous oil tube at least comprises a section of pipe I with the gradually changed wall thickness and a section of pipe II with the gradually changed wall thickness which are connected end to end; the first end of the pipe I with the gradually changed wall thickness is a connector section I with equal wall thickness, the middle part of the pipe I is a section I with the changed wall thickness, and the tail end of the pipe I is a connector section II with equal wall thickness; the first end of the pipe II with the gradually changed wall thickness is a connector section III with equal wall thickness, the middle part of the pipe II is a section II with the changed wall thickness, and the tail end of the pipe II is a connector section IV with equal wall thickness; the connector section II with equal wall thickness is butted with the connector section III with equal wall thickness, and the wall thickness of the connector section II with equal wall thickness is the same with that of the connector section III with equal wall thickness; and the wall thicknesses of the section I with the changed wall thickness and the section II with the changed wall thickness from the first ends to the tail ends are gradually reduced. According to the invention, the oil tube is made of a steel strip with the gradually changed thickness along a length direction, so that the wall thickness of the continuous oil tube is gradually changed continuously in the length direction, the self-weight of the continuous oil tube is reduced under equal length, the pulling force on the continuous oil tube in a wellhead section is reduced, and the operation depth of the continuous oil tube and the operation safety are improved.

Description

technical field [0001] The invention relates to the technical field of oil and gas pipes, in particular to a coiled oil pipe with gradually changing wall thickness and a manufacturing method thereof. Background technique [0002] Coiled tubing has been widely used in oil field workover, drilling, completion, logging, stimulation and other fields in the oil and gas industry. Due to the advantages of high efficiency, low cost, wide operation range and small footprint in the above operations, coiled tubing technology has developed rapidly in recent years. [0003] During use, the coiled tubing needs to be led out from the reel, and enter and hang in the wellbore through the guide arch (gooseneck) and injection head. For shallow wells with small depth, ordinary coiled tubing can meet the requirements. However, when the coiled tubing is used in deep or ultra-deep wells, the suspension weight and lifting force of the coiled tubing will increase significantly as the running depth...

AI Technical Summary

Problems solved by technology

[0006] At present, the pipe-tube butt welding of finished coiled tubing with different specifications can realize the variable wall thickness requirements of coiled tubing. The wall thickness of the pipe is closely related. Whether manual welding or automatic welding is used, the stepped joint will be formed. The performance of the weld and the base metal is quite different. When deformation occurs, it is easy to fail prematurely at the girth weld due to the different deformation of each part.

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