3D Geological Modeling and Heterogeneity Characterization of the Deng-2 Gas Reservoir in Gaoshiti Area, Central Sichuan Basin

The Anyue Gas Field in the Sichuan Basin features a large resource scale in the Gaoshiti Member 2 (Deng 2 Member) gas reservoir, with proven reserves largely confirmed. It serves as a crucial replacement production area for the unexploited regions of the Gaoshiti block in the Southwest Oil & Gas Field. However, such reservoirs are influenced by complex structural backgrounds, multi-phase sedimentary stacking, and karstification, resulting in strong reservoir heterogeneity and significant challenges in predicting reservoir architecture and characterizing spatial distribution. To achieve refined reservoir characterization, this study systematically conducted structural modeling, sedimentary facies modeling, and reservoir property modeling based on 3D seismic data, well log interpretation, and core analysis. First, a high-precision structural model was established through fault combination analysis and stratigraphic trend constraints to clarify structural details. Next, by integrating planar sedimentary facies analysis, sequential indicator simulation was employed to construct the sedimentary facies model. Furthermore, based on facies-controlled modeling, variogram analysis was performed, and sequential Gaussian simulation was applied to develop 3D property models for porosity, permeability, and saturation, quantitatively characterizing the “west-high, east-low” heterogeneous distribution of reservoir properties. Through multi-method collaborative 3D geological modeling integrating “structure-sedimentation-properties,” this study enhanced the spatial characterization of heterogeneity in the Deng 2 Member dolomite reservoir. The results clarify that favorable facies belts—microbial mounds and algal debris shoals—are distributed in an alternating banded pattern, with high-porosity zones (> 2%) predominantly developed in the eastern and central regions. The research findings have supported the optimization of gas field development plans and well placement, providing theoretical and practical guidance for the refined characterization and efficient development of similar strongly heterogeneous carbonate gas reservoirs.