High temperature and high pressure coal rock supercritical carbon dioxide fracturing-creep deformation-seepage experimental method

Abstract

The invention discloses a high temperature and high pressure coal rock supercritical carbon dioxide fracturing-creep deformation-seepage experimental method. A supercritical carbon dioxide fluid fracturing-creep deformation-seepage experiment of coal rock is executed under high temperature and high pressure, change of temperature and pressure of the supercritical carbon dioxide and fracture crackinitiation and expansion features in a supercritical carbon dioxide fluid fracturing process are monitored and recorded in real time, and axial deformation and radial deformation of a coal rock sampleare monitored and recorded in real time, moreover, CH4 permeability of the coal rock before and after fracturing can be measured directly and effectively under a condition where coal rock sample stress is not cancelled, and measurement of the permeability of the CH4 of the coal rock under the creep deformation function after fracturing can be realized. The measurement method provided by the invention is high precise, visual and highly automatic, and devices used in the method are simple in structure.

Description

technical field [0001] The invention relates to a coal rock supercritical carbon dioxide fracturing-creep-seepage test method under high temperature and high pressure. The fracturing medium is supercritical carbon dioxide, which belongs to the field of rock mechanics and engineering technology. Specifically related to deep coalbed methane mining, using supercritical carbon dioxide as a fracturing medium to fracture coal rock samples, real-time monitoring and recording of supercritical carbon dioxide temperature, pressure changes and fracture initiation and expansion during supercritical carbon dioxide fracturing characteristics, and simultaneously monitor and record the axial and radial deformation of the coal sample in real time, and measure the gas permeability of the coal sample before and after fracturing under the condition of not unloading the stress of the coal sample, and obtain the pressure The change rule of the permeability of the cracked coal rock sample under the ...

AI Technical Summary

Problems solved by technology

The existing true triaxial fracturing simulation test devices and methods can simulate hydraulic fracturing and other gas fracturing tests under the conditions of temperature and stress in deep buried formations, but it is difficult for true triaxial fracturing devices to directly measure the post-fracture Gas Permeability of Square Specimen

And for the existing triaxial fracturing device (cylindrical sample), such as CN 105510142 A, it is difficult to directly measure the permeability of the sample before and after fracturing accurately under the stress condition of not unloading the sample, and it is difficult to realize Under the conditions of high temperature (300°C) and high pressure (70MPa), acoustic emission technology is used to accurately and reliably monitor the crack initiation and expansion characteristics of the sample during the fracturing process, and to observe, analyze and grasp the formation and expansion of cracks mechanism

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