Numerical simulation of acid-fracturing multi-field coupled production capacity in carbonate reservoirs with ultra-deep fault-grid structures

The Tarim Basin’s ultra-deep fault-grid carbonate oil reservoirs have complex oil and gas flow conditions, which severely limit the degree of resource utilization. However, existing production prediction models struggle to accurately forecast the productivity of such reservoirs. Based on the discrete fracture-cavity method, the two-phase oil-water flow model for the fault-grid structure was established. Sensitivity analysis of production capacity was conducted under different structures. Additionally, the main controlling factors were identified using the PLSR. The research results indicate that for the single fault-single grid structure, as the grid width increases, both the daily oil production and cumulative oil production after 10 years show an upward trend. When the displacement of the acid is 10 m³/min, the cumulative production reaches the maximum value. As the acid volume increases, the cumulative oil production after the stimulation shows an increasing trend, but the rate of increase gradually decreases. For both the single fault-single grid and single fault-multiple grids structures, the stimulation model is the primary controlling factor. However, for the multiple faults-multiple grids structure, the number of faults is the main controlling factor. This study provides valuable guidance for the optimization of acid fracturing process parameters for ultra-deep fault-grid carbonate oil reservoirs.