Abstract: The occurrence depth has a significant effect on the rock mechanical properties of shale reservoir. The deformation and failure mechanism of deep shale was studied to obtain the law of the effect of occurrence depth on the rock mechanical parameters and provide crucial basic parameters for shale oil and gas development. Rock mechanics experiments were conducted with shale rock samples at different depths to analyze the key mechanical properties of deep shale were analyzed and obtain the variation law of its strength parameters and deformation modulus. The results showed that deep shale was significantly different from shallow shale in terms of mechanical strength, resistance to deformation and failure, and fracture mode. With the increase of depth, the strength of the shale gradually increases and the brittleness gradually deteriorates, leading to more difficulties in fracturing stimulation. Most rock mechanical parameters were strengthened with the increase of confining pressure. Confining pressure, density, etc. are the key factors affecting the mechanical performance of deep shale. Changes in the mechanical properties of deep shale greatly affect the initiation, turning and other mechanical behavior of fracturing fractures. The fracture generation capability of deep shale gradually decreases with the increase of the occurrence depth. The research results provide important reference and theoretical basis for the evaluation of deep shale reservoirs and the practice of drilling and completion.

Key words: shale gas, rock mechanics, reservoir stimulation, fracture mode, fracture propagation, deep shale