Abstract:For the horizontal well cementing and completion of the conglomerate reservoir of the Baikouquan formation in the Mahu Sag after perforation, the direct fracturing construction has some problems in high pump pressure and need to long-time acid soaking technology to reduce the fracturing start pump pressure. The mechanism of acid damage and depressurization is studied after reservoir perforation in this paper. Firstly, the acid-rock reaction experiment of reservoir cores and cement stones in blocks of Mahu 1, Ma 131, and Ma 18 was carried out at the simulated temperature, and the macroscopic dissolution rate and the variation law of cores and cement stones were obtained. Secondly, the triaxial mechanical experiments on cores and cement in blocks of Mahu 1, Ma 131, Ma 18 before and after acid rock reaction were carried out, and the mechanical characteristics and changes of rock/cement stone before and after acid reaction were obtained. Thirdly, SEM, EDS and XRD were used to analyze the changes of pores/fractures/surfaces microstructure before and after acid treatment, and the mechanism of acid rock reaction was explored from the microscopic point of view. Finally, based on the Mahu fracturing construction parameters, the results of SEM/EDS/XRD analysis of rock and cement stone before and after acid reaction and the triaxial mechanical properties of rock/cement stone before and after acid rock reaction, the effect of acidizing treatment on formation fracturing pressure is analyzed by adopting seven-five model and fracture pressure formula, and the mechanism of acid damage and pressure reduction after perforation of horizontal well cementing and completion in Mahu conglomerate reservoir is revealed.