High-Precision Productivity Prediction of Fractured Wells in Low-Permeability Reservoirs

Long-fractured vertical wells have been widely applied to improve the productivity of low-permeability reservoirs in Area A. However, an efficient and accurate productivity prediction method for the target reservoir has yet to be established. This study aims to clarify the effects of reservoir and fracture parameters on productivity under different formation permeability conditions and to develop a practical productivity prediction method for long-fractured vertical wells. A three-dimensional reservoir numerical simulation model was established to analyze the effects of basic reservoir, well, and fracturing parameters on daily oil production. The results show that daily oil production from the X oil layer increases with formation permeability, effective reservoir thickness, production pressure drawdown, fracture half-length, fracture width, and fracture permeability, but decreases with water saturation, crude-oil viscosity, and skin factor. Numerical simulation further indicates that a fracture half-length of approximately 200 m, fracture permeability of about 300 D, and fracture width of around 6 cm provide favorable productivity responses under the studied conditions, providing a basis for fracturing parameter selection. Based on fractured-well flow theory and triangular fracture morphology, a productivity prediction model was subsequently established. The initial agreement rate between the predicted and well-test productivity values was 81.1%. For layers with discrepancies between the predicted and tested productivity values, numerical simulation was further used to adjust the relevant model parameters, increasing the agreement rate to 91.0%. These results represent a field benchmarking of the consistency between predicted and measured productivity. The proposed method integrates reservoir characterization, numerical simulation, and flow theory, providing an efficient approach for productivity prediction of long-fractured vertical wells in low-permeability reservoirs. The results provide insights into the effects of reservoir and fracture parameters on productivity and a practical reference for fracturing design and reservoir development.