A WELL TESTING ANALYSIS AND PRODUCTION PREDICTION MODEL FOR FRACTURED-VUGGY CARBONATE FRACTAL RESERVOIRS

Carbonate reservoirs will form complex pore structures inside after undergoing fracture, dolomitization and dissolution. As the main reservoir space of fluid, the pore structure has an important influence on fluid flow and oil and gas production. In this paper, a multi-region linear seepage analysis well testing model considering fractal theory, matrix effect and cave is proposed for fluid flow state characterization and productivity evaluation of fractured-vuggy carbonate reservoirs. By establishing a mathematical model, the analytical solution of bottom hole pressure and production is derived in the Laplace domain. Using Stehfest’s numerical inversion, the bottom hole pressure and production curve in the time domain are drawn. By comparing with the actual production case, the reliability of the model is verified. We analyze the two-cave model and divide it into six flow stages. Through the study of pressure behavior, it can be seen that the pressure is greatly affected by the fractal and cave storage coefficient. The larger the fractal dimension is, the smaller the fractal index is, the better the reservoir porosity and permeability connectivity is, and the time for the fluid to reach each flow stage is shortened, which is helpful for oil and gas production to increase production and efficiency. The distance of the cave mainly affects the occurrence time of cave storage flow. When the cave with a large storage coefficient is closer to the main fracture, a higher daily oil and gas production can be obtained in the oil and gas production cycle.