不同热破裂温度下煤岩的孔裂隙演化特征研究

Study on Fracture Evolution Characteristics of Coal Rock at Different Thermal Fracture Temperatures

为了研究不同温度下煤页岩的细观孔隙结构,对经过20、100、300、500℃热破裂温度下的煤岩试样进行微米CT扫描试验,基于阈值分割算法得到了三维孔隙重构模型,并分析了孔隙率、孔喉尺寸参数和孔隙连通度的量化指标随温度变化的关系。结果表明,利用CT扫描技术获得煤岩的二维切片,经过重构可得到三维孔隙结构模型;表征孔隙含量的孔隙率与温度呈指数型函数关系;最大孔喉长度L和平均孔喉半径R随温度上升的增速呈先慢后快的特点;煤页岩的孔隙连通度随环境温度的升高保持初期迅速上升,在中期缓慢上升,到后期有所下降的变化。

To study the mesoscopic pore structure of coal shale rock under different temperatures, Micron CT scanning test was carried out on coal and rock samples at thermal fracture temperatures of 20, 100, 300 and 500 ℃. Based on the threshold segmentation algorithm, the three-dimensional pore reconstruction model is obtained, and the relationship between the pore ratio,pore throat size parameters and the quantitative index of pore connectivity with temperature is analyzed. The results show that the two-dimensional sections of coal and rock are obtained by CT scanning technology, and the three-dimensional pore structure model can be obtained by reconstruction. The relationship between porosity and temperature was exponential. The maximum pore throat length L and average pore throat radius R increase slowly and then rapidly with the increase of temperature. The pore connectivity of coal shale increased rapidly in the initial stage with the increase of ambient temperature, slowly increased in the middle stage, and decreased in the later stage.