Method for molding expandable bellows

Abstract

The invention provides a method for molding an expandable bellows, which relates to drilling technology. The method comprises the following steps that: a round pipe which is heated to be between 500 and 1,200 DEG C is axially moved, a set or more than one set of pre-molded rolling shafts and molded rolling shafts are arranged at the periphery of the pipe wall along the movement direction, each set of rolling shafts consist of two groups of rolling shafts which are arranged at cruciformly symmetrical positions on the cross section of the round pipe respectively, and each group of rolling shaft consists of two roller wheels with axial lines perpendicular to the movement direction of the round pipe and rotation direction symmetrical to the movement direction and symmetrical shape; the distance of the two opposite roller wheels is smaller than the outer diameter of the pipe; and one group of rolling shaft in the rolling shafts is consistent with one group of rolling shaft with the same shape in other sets of rolling shafts at the cruciformly symmetrical positions on the cross section of the round pipe, and the distance of the symmetrical roller wheels of each set of rolling shafts is gradually reduced. Internal molds are arranged in the pipe at the positions corresponding to the molded rolling shafts, which ensures that the pipe is molded into the expandable bellows after passing through the rolling shafts during axial movement. The collapse strength of the expandable bellows after the expansion achieves more than 8MPa, and the internal pressure strength is more than 30MPa.

Description

technical field [0001] The present invention relates to a preparation method of an expandable pipe, and more specifically, relates to a preparation method of an expandable corrugated pipe used in the drilling process. Background technique [0002] Expandable tubular technology is to lower the tubular string into the well during the drilling or workover construction, and permanently deform the tubular string by means of hydraulic or mechanical force, so as to increase the diameter of the casing, realize the saving of borehole size, sealing A new technology for plugging complex formations and repairing damaged casing. Expandable pipes can be used in drilling, completion and workover operations, and are considered to be one of the core technologies in the oil drilling industry in the 21st century. [0003] When complex formations such as lost circulation formations appear during drilling, the lost circulation must be plugged. In the course of engineering practice, it often ha...

AI Technical Summary

Problems solved by technology

However, the expansion solid pipe has relatively high requirements on the pipe material. The material must have high strength and good ductility. The production cost is much higher than that of the corrugated pipe, and its expansion rate is not as good as the corrugated pipe. The on-site operation is also more complicated.

[0010] At present, only Russia produces corrugated expansion pipes abroad, and its "8" cross-section corrugated pipes are formed by cold pressing, which is only suitable for steel pipes with low strength, and the expanded corrugated pipes have relatively low external extrusion strength and internal pressure resistance. low, which limits its range of application

For high-strength steel pipes, there is a large rebound after forming, and the cross-section of the rolled pipes is inconsistent, making it difficult to connect the bellows

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