Extending Regularity of Acid Fracturing in Deep Fractured-Vuggy Carbonate rocks—A Case Study of Qixia Formation in Western Sichuan

Acid fracturing has become an important tool for reservoir transformation. With the complex spatial morphology and high heterogeneity of the deep fractured-vuggy carbonate reservoir, it is difficult to develop it effectively. In this paper, indoor true triaxial acid fracturing simulation experiments and 3D scanning were carried out to analyze the acid fracture propagation morphology and study the process of crack propagation. Rock mechanical parameters were tested to indicate the degree of rock strength deterioration at different locations. The experimental results show (1) The acid fracturing affects the mechanical properties of the formation around the fracture, Young's modulus, and Poisson’s ratio of the rock around the wellbore decreased by 34.42 and 18.18%, respectively. The degree of acid corrosion at the distal end gradually decreased. (2) Natural fractures affect acid fracturing significantly. (3) Compared to the single acid injection construction, fatigue acid fracturing reduces the fracture pressure by 18.75%, and the fracture propagation pattern is more complex.