Continuous oil pipe with gradual changing wall thickness and production method for continuous oil pipe

Abstract

The invention discloses a continuous oil pipe with a gradual changing wall thickness and a production method for the continuous oil pipe. The continuous oil pipe is provided with at least one section of pipe with the gradual changing wall thickness, a head part and a tail part of each pipe with the gradual changing wall thickness are respectively butted with a section of equal wall thickness pipe I and a section of equal wall thickness pipe II, outside diameters of the equal wall thickness pipe I, the pipe with the gradual changing wall thickness, and the equal wall thickness pipe II are same, the wall thickness of the pipe with the gradual changing wall thickness is gradually decreased from a head end to a tail end, an inside diameter of the head end of the pipe with the gradual changing wall thickness is same to that of the equal wall thickness pipe I, and the inside diameter of a tail end is same to that of the equal wall thickness pipe II. The continuous oil pipe is made of steel bands with a thickness gradually changing along a length direction, abutting joints of the steel bands are welded by two boards with equal wall thicknesses, and the mechanical property of each weld joint after a deformation heat treatment is matched with that of a base material, thus the wall thickness of the continuous oil pipe is enabled to be changed gradually in the length direction, a self-weight of the continuous oil pipe is decreased in the situation of a same length, the pulling force borne by the continuous oil pipe in a wellhead section is enabled to be reduced, and an operation depth and the operation safety of the continuous oil pipe 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-to-pipe butt welding connection of finished coiled tubing with different specifications can realize the variable wall thickness requirements of coiled tubing, but when welding two kinds of coiled tubing with different wall thickness, due to the heat input, welding speed, and filler metal content are different It is closely related to the wall thickness of the pipe. Whether manual welding or automatic welding is used, a stepped joint will be formed, and the properties of the weld and the base metal are quite different. fail

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