Characterization of 3d Micro-Cracks in Shales Generated During Pyrolysis Experiments and Its Implications for Reservoir Stimulation

In this study we investigate the efficiency of pyrolysis for the generation of cracks in reservoirs necessary for the development of hydrocarbons, particularly for deeply buried and unconventional oil and gas. Six organic-rich shale samples from the Junggar Basin, western China, were heated to induce micro-cracking by pyrolysis. Fracture networks are separated into individual cracks using a novel X-Ray micro-tomography-based workflow. Individual cracks were identified and segregated, then characterized for their length, width, thickness, orientation, etc. The occurrence and distribution of cracks were obtained statistically, and the fractal dimension of crack length was also extracted. Results show that crack parameters are controlled by the bedding structure of the shale, the heterogeneity of samples, and the heating temperature. Parameters including porosity, specific surface area, percolation, and the fractal dimension show distinct contrast below and above 350 ºC, which is the threshold temperature for gas generation during pyrolysis experiments. The analysis quantifies the efficacy of pyrolytic stimulation methods and paves the way for the development of novel stimulation protocols for unconventional hydrocarbon and other resources.