Research on Productivity Prediction Method of Sandstone Reservoir Based on Logging Permeability Synthesis Technology

Using conventional logging data to accurately calculate drill stem test (DST) permeability can greatly improve the productivity prediction accuracy of offshore heterogeneous sandstone reservoir. Therefore, considering the influence of macro sedimentary diagenesis and micro pore structure on reservoir permeability in Huizhou sag, the logging interpretation models of absolute permeability of different reservoir types are established. Analysis results show that the contribution of reservoirs with different permeability levels in perforated intervals to productivity is obviously different. The synthetic logging permeability is obtained by weighted summation of reservoir permeability at different levels, and the weight coefficient is constrained to highlight the contribution of advantageous reservoirs to productivity. Finally, the regression fitting equation of DST test permeability is established, the optimal solution of DST test permeability equations is obtained by continuous iteration of differential evolution algorithm. This technology is used to predict the productivity of 72 oil layers in Huizhou Depression. For 48 oil layers with productivity greater than 100 m3/d, the proportion of prediction relative error less than 30% is 90%, and for 24 oil layers with productivity between 10-100 m3/d, the proportion of relative error less than 50% is 79%. The productivity prediction method based on new permeability synthesis technology can provide effective guidance for offshore field testing and greatly reduce the cost of exploration.