Numerical simulation of hydraulic-mechanical-chemical field coupled acid fracturing in complex carbonate reservoir

Abstract

In a fractured-vuggy carbonate reservoir (FVCR) are distributed many irregular natural fractures and cavities. The acid fracturing is an effective stimulation method for FVCR. It involves the hydraulic, mechanical and chemical (HMC) field coupling process. To effectively simulate the acid fracturing in FVCR, the natural fractures are hierarchically treated. For the large fractures, which play the leading role in all physical fields, the fully coupled model is adopted. While for the small fractures, which play the leading role in part physical fields, the partly coupled model is adopted. By this means, the computation stability and efficiency are significantly improved. This is particular important for the field scale simulation of FVCR. Besides this, the acidization of the natural fracture in the inactive and activated states are considered. The simulation results suggest that this method can well simulate the acid fracture activation, propagation, interaction with natural fractures and connection with cavities in FVCR. It provides a stable and efficient approach for the acid fracturing simulation in complex FVCR.