Flexible pipe assisted type pipeline returning method

Abstract

The invention relates to a flexible pipe assisted type pipeline returning method. A high-intensity water isolation flexible pipe matched with a pipeline is placed in the pipeline; the flexible pipe and the pipeline are tightly installed employing an arc-shaped pressing plate and fastening bolts on the inner side of the inlet end of the pipeline; slurries in a drill hole enter in the flexible pipethrough a slurry channel of an open type pipe drawing device when the pipeline is returned; after the pipeline is returned, the slurries in the flexible pipe are pumped off from two ends of the pipeline by two submersible pumps; and the flexible pipe is taken out to finish the pipeline returning operation. The method provided by the invention can reduce slurry buoyancy acting on the pipeline whenthe pipeline is returned so as to improve stress state of the pipeline in a pipeline returning process; meanwhile, the method can improve pressure state and flow state of the slurries in the drill hole in the pipeline returning process so as to lower the risk of the pipeline returning process. The method provided by the invention is simple to operate and has the advantages of time saving, safe construction, wide application range and the like.

Description

technical field [0001] The invention relates to a hose-assisted pipeline pullback method, in particular to a method that can be used for horizontal directional drilling without causing contamination to the inner wall of the pipeline during the pullback process of the pipeline, and can avoid the occurrence of excessive buoyancy of the pipeline during pullback. The open-type hose-assisted pipeline back-drag technology, which floats up and presses the upper wall of the borehole to prevent the drastic increase of the annular mud pressure and reduce the risk of back-drag, belongs to the field of geological engineering. Background technique [0002] In horizontal directional drilling engineering, due to the cleanliness and integrity of the pipeline, when horizontal directional drilling is used to pull back the pipeline, a closed pullback device is usually used to tightly connect the pipeline or the inlet end of the pipeline is sealed by other means to prevent During pullback, the ...

AI Technical Summary

Problems solved by technology

Taking a steel pipe with a diameter of 1219mm and a wall thickness of 22mm as an example, the buoyancy of the mud on the pipe after entering the borehole is more than twice the weight of the pipe. The huge buoyancy will make the pipe tightly pressed against the upper wall of the borehole, greatly Increased resistance and risk in the pullback process

[0004] In addition, in the process of closed dragging back, the mud will be discharged from the annulus between the borehole and the pipeline for a long period of time, and the reduction of the circulation channel will lead to the rapid rise of the mud pressure during the dragging back process, resulting in formation uplift or compression. At the same time, a large number of solid particles in the mud and the falling blocks during the back-drag process are easy to stagnate or block the annulus when they flow through the annulus, which increases the resistance of the back-drag and even causes pipe holding and jamming, which increases the Risks in the process of pulling back the pipeline

Images