Adaptability Study and Optimization Evaluation of Encrypted Well Network in Low-Permeability Reservoirs

In this study, the adaptability of encrypted well network and the evaluation of well network optimization are discussed in depth for the characteristics of medium and low permeability fracture nature in the long 6 reservoir of Ansai Oilfield, in order to improve the development efficiency and economic benefits of the oilfield. By comprehensively analyzing the geological structure of the reservoir, the form of injection and extraction well network and the degree of water drive utilization, the influence of well spacing, row spacing and water injection pressure on the recovery rate was studied. The results show that increasing the water injection pressure from 35MPa to 40MPa can increase the degree of water drive utilization from 45% to 58%. In terms of well network configuration, when reducing the injection and recovery well spacing from the conventional 550 m to 150 m, the degree of reservoir mobilization can be significantly increased from about 60% to nearly 100%. In addition, by adjusting the spacing to 125m, the utilization of the formation can be further increased to more than 90%, which shows a significant improvement compared to 70% under the traditional spacing. In addition, the simulation of different combinations of spacing and injection/production well spacing shows that smaller combinations of well spacing and spacing can effectively improve the degree of water drive control and reservoir utilization efficiency. Comparison of well network encryption schemes shows that, while keeping the injection/extraction ratio and the number of wells unchanged, the inverse nine-point well network scheme with diagonally encrypted wells can significantly improve the development efficiency and economic benefits of the field, with Scheme 5 showing the best performance in terms of oil recovery and integrated water content. These results not only provide a scientific basis for the refined well network design and optimization of the long 6 reservoir in Ansei Oilfield, but also provide important theoretical support and practical guidance for the development of similar low-permeability fractured reservoirs. The study emphasizes the importance of maximizing the development effect by scientifically adjusting well network parameters, demonstrating clear theoretical value and practical significance.