Analysis on Controlling Factors of Effective Reservoir in Intra-platform of Sinian Dengying 4th Member in Central Sichuan

With the completion of 6.3 × 108m3/a production capacity construction in the platform margin of Sinian Dengying 4th Member, the focus of exploration and development of Dengying Formation in Anyue gas field has gradually shifted to the intraplatform domain. Gas test and production test show that the productivity and well controlled reserves of gas wells in intraplatform domain are highly heterogeneous, and the large-scale benefit development is facing great challenges.Based on the analysis of the type of karstification in Dengying 4th member of Sinian system and the difference of reservoir characteristics between the platform margin and the intraplatform, the paper pointed out that the platform margin is dominated by supergene karst and superimposed deep buried karst, while the supergene karst in the intraplatform is weak and the local superimposed buried karst transformation is strong.The difference in sedimentary microfacies and karst paleogeomorphic features between the intraplatform and the platform margin is the reason why the development degree of high-quality reservoirs in the intraplatform is worse than that in the platform margin, while the deep karstification transformation in the intraplatform belt is stronger than that in the platform margin, which is the main factor for the formation of high-quality reservoirs under the background of poor supergene karstification in the platform, That is, the favorable sedimentary microfacies and favorable supergene karst paleogeomorphology in the intraplatform control the development range of effective reservoirs, and the deep buried karst related to faults is the main controlling factor for the formation of high-quality reservoirs. The further clarification of the main controlling factors of effective reservoirs in the intraplatform, especially high-quality reservoirs, provides a basis for the favorable areas optimization and benefit development in the intraplatform of Sinian Dengying 4th Member in Anyue gas field.