Calculation method for micro-crack thermally induced conductivity of hot dry rock mass

Abstract

The invention discloses a calculation method for micro-crack thermally induced conductivity of hot dry rock mass. The method comprises the following steps: S1, collecting a dry hot rock mass reservoir core containing a micro-crack, and carrying out laser scanning to obtain two-dimensional morphology data of the micro-crack, and S2, calculating a roughness coefficient of the micro-crack according to the two-dimensional morphology data; S3, according to the in-situ stress state and the mechanical strength of the hot dry rock mass, calculating the initial mechanical opening degree of the hot dry rock mass micro-crack; S4, calculating the temperature field of the wall surface of the micro-crack in a hydraulic fracturing long-term injection process in combination with rock thermophysical parameters of the dry hot rock mass; S5, according to the temperature drop and mechanical parameters of the wall surface of the micro-crack of the hot dry rock mass, calculating the thermal induction opening degree of the wall surface of the micro-crack in the hydraulic fracturing long-term injection process; and S6, according to the initial mechanical opening degree and the thermal induction opening degree, calculating the flow guide opening degree, the thermal induction flow guide capacity and the micro-crack comprehensive conductivity capability at any position of the dry hot rock mass micro-crack. The method provided by the invention can accurately calculate the comprehensive flow conductivity of the micro-crack after the hot dry rock transformation.

Description

technical field [0001] The invention relates to the technical field of stimulation and transformation of cracked hot dry rock mass, in particular to a calculation method for thermally induced conduction capacity of micro-fractures of hot dry rock mass. Background technique [0002] The hydraulic fracturing process is one of the most effective transformation methods for the economical and efficient development of deep hot dry rock geothermal resources. The water flow channel with induced conductivity can realize the purpose of high-efficiency injection and production and heat exchange. [0003] The thermally induced conductivity is composed of the original mechanical opening and the thermally induced opening. The original mechanical opening is the opening determined by the roughness of the micro-fractures in the dry hot rock mass in situ, and the thermally induced opening is the opening of the high temperature dry hot rock. The strain opening of bulk micro-fractures caused b...

AI Technical Summary

Problems solved by technology

[0004] At present, the roughness of micro-cracks in dry-hot rock mass is often calibrated multiple times with outcrop cores. Artificial multiple calibrations can neither cover the entire two-dimensional plane nor accurately measure the height of micro-cracks, resulting in roughness The deviation between the calibration result and the real data is too large; micro-cracks in dry-hot rock mass are often assumed to be planar cracks, which are closed and compressed under the in-situ stress. In the diversion calculation, they are defaulted as invalid diversion channels, ignoring the surface of rough micro-cracks The original mechanical opening formed by self-support; the temperature drop of the micro-crack wall surface of high-temperature rock mass is often directly expressed by the difference between the temperature of high-temperature rock mass and the temperature of injected cold fluid, ignoring the stable heat source effect of high-temperature dry-hot rock mass, and cannot Accurately calculate the temperature drop change in the length direction, and the calculated temperature drop and thermally induced opening are both greater than the actual value

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