Identification and Capacity Analysis of Ultra-Deep Carbonate Gas Reservoirs

In this study, reservoir identification and capacity analysis of ultra-deep carbonate gas reservoirs are discussed in depth, with special focus on the Middle Permian gas reservoirs in West Sichuan area. By systematically analyzing the reservoir characteristics, tectonic features and their influence on the production capacity in this region, this paper proposes a set of comprehensive evaluation methods to improve the accuracy of reservoir identification and production capacity evaluation. The study shows that the reservoirs of the Middle Permian gas reservoirs in the West Sichuan area have obvious non-homogeneity and multi-scale seam characteristics, with porosity ranging from 0.22% to 10.8% and permeability ranging from 0.0011 to 56 mD, and their production capacity is affected by a variety of factors, such as the physical properties of the reservoirs, the degree of fracture development, and the degree of active water bodies. By analyzing the meter gas recovery index curve, this study successfully identifies different types of reservoirs, and proposes a capacity evaluation model applicable to carbonate reservoirs based on the pressure drop dynamic characteristics of dual-media reservoirs. The results show that the equivalent formation coefficient F_e, the non-homogeneous coefficient λ and the equivalent number of fracture strips N_f are the key factors affecting the production capacity of gas wells. Among them, the unimpeded flow rate q_AOF increases with the increase of equivalent formation factor F_e, while the production ratio α has no obvious correlation with equivalent formation factor F_e. In addition, the equivalent water intrusion intensity Iwe has a significant effect on the gas well allotment ratio, which decreases with the increase of water body activity. This study provides theoretical support and technical guidance for the effective development of ultra-deep carbonate reservoirs, and is of great significance for guiding actual production, formulating development countermeasures and rationalizing production allocation.