Optimization of Criterion for Rock Crack Propagation under Acid Izing Treatment

Since most of the conventional oil and gas resources have been intensively investigated, unconventional oil and gas resources such as deep marine carbonate reservoirs and heavy oil reservoirs have become the primary focus in the exploration and development of oil and gas. The oil and gas reservoirs with complex fracture geometries account for nearly 45% of the global oil and gas reserves, and the production of such complex fractured oil and gas reservoirs accounts for nearly 60% of the total natural gas production. Consequently, fractured oil and gas reservoirs have received considerable research attention in recent years. Further, fractures determine the permeability and productivity of petroliferous reservoirs. In this paper, we have investigated the current status of research on petroliferous rock under the action of acid etching. At the same time, we have summarized the existing rock fracture propagation criterion and crack propagation criterion theory, and selected the most common crack propagation criterion for setting simulation parameters. Subsequently, the Brazilian split test and the rock acidification sensitivity experiment are combined, and the comparative experiment method is used to obtain the hydrochloric acid concentration and acidification treatment time that can meet the DIC optical test. Through the DIC method, the expansion of rock cracks from the moment of loading of experimental species to the moment when the completion of splitting is recorded, the strain and displacement of each point on the rock surface during the Brazilian splitting test are obtained. Finally, through the ABAQUS software, different fracture propagation criteria are used to simulate the fracture propagation process in the rock samples in the Brazilian fracturing test, and the results are recorded. Then, the expansion model is selected that best fits the carbonate fracture before and after acid etching. The in-situ stress field of the fault zone in the Shunbei area is exceedingly complex. Based on the Shunbei area, the model is set up. Furthermore, the features of plane geomechanics are studied, and the fracture propagation laws of acid salt reaction are analyzed. The results provide the basis for optimizing the acid fracturing technology and construction parameters in the Shunbei area.