ROCK MECHANICS AND FRACTURE CHARACTERISTICS EXPERIMENT OF PERMIAN VOLCANO RESERVOIR IN SICHUAN BASIN

The Permian volcanic rock reservoir in the Sichuan Basin is a gas reservoir of volcanoclastic of volcano eruption. It is a porous reservoir with low natural production. It is difficult to develop effectively without reservoir stimulation. In order to evaluate the potential for stimulation and feasibility of reservoir stimulation measures, this study uses drill cores and field outcrops to test and analyze the rock mechanics and fracture characteristics of Permian volcanic reservoirs in the Sichuan Basin. The test results show that: (1) The rock mechanics and fracture characteristics of the Permian volcanoclastic drill core in the Sichuan Basin are similar to that of the outcrop core in the Sayutuo section of Yanjin, Yunnan; (2) The rock mechanics of the volcanoclastic rock is brittle in uniaxial state. Under the triaxle state. it shows plastic characteristics, and under the plastic characteristics, the difference between residual stress and yield stress is small; (3) The rock mechanical heterogeneity of volcanoclastic rocks is strong. and the difference coefficient is large, the difference coefficient is greater than 30% under uniaxial state, in the triaxle state is still high. in which the tensile strength and Young's modulus are greater than 10%; (4) The fracture characteristics of volcanoclastic rocks are generally irregular fragmentation, with very complex fracture forms; Shear failure and tensile failure are both manifested; (5) The phenomenon of "Particles fall" after the failure of the volcanoclastic rocks sample was observed in the test is consistent with the characteristics of "sand production" under the field conditions. Through this research, the rock mechanics and fracture characteristics of Permian volcanic reservoirs in the Sichuan Basin have been clarified, and the research results can provide technical support for the subsequent development of the block.