Well casing recovery method

Abstract

The invention relates to the technical field of well drilling, in particular to a well casing recovery method. The method comprises the following steps of S1, injecting a quantitative binding material into a drilling well and forming a fixed isolation layer in the drilling well; S2, separating the well casing above the isolation layer; S3, sealing the mouth of the drilling well; S4, conveying refrigerating liquid into the drilling well, forcibly cooing and shrinking the well casing and separating the same from a well cementing cement ring, wherein the refrigerating liquid absorbs heat, is vaporized, is converted to gas and is discharged from an air outlet pipeline; S5, removing the sealing of the mouth of the drilling well; S6, lifting the well casing. The method realizes the effective recovery of the well casing.

Description

technical field [0001] The invention relates to the technical field of drilling, in particular to a drilling casing recovery method. Background technique [0002] Underground coal gasification is a process in which the underground coal is directly burned in a controlled manner to generate combustible gas through the thermal and chemical effects of the coal. This process integrates the three major processes of well construction, coal mining, and surface gasification, changing traditional coal mining to chemical coal mining, eliminating the need for huge equipment for coal mining, transportation, washing, gasification and other processes, so it is safe It has the advantages of good performance, less investment, high efficiency and less pollution. [0003] The realization process of UCG is to drill several wells with different functions on the ground to the target coal seam of gasification, and then carry out a series of operations such as coal seam ignition, drainage and drai...

AI Technical Summary

Problems solved by technology

However, in the actual work of underground coal gasification at present, after the completion of the mission, the drilling well is generally in the state of environmental protection observation, abandoned or blocked, and the recovery and reuse of the drilling casing is rarely carried out.

The fundamental problem that restricts the recovery and reuse of drilling casings is that there is still no set of effective methods and technical measures to solve the problem of recovery of drilling casings for underground coal gasification.

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