3D geological modeling of strongly heterogeneous dual-medium deep carbonate reservoirs： A case study of Feixianguan-Changxing Formations in Puguang Gas Field

The carbonate reservoir in Puguang Gas Field has the characteristics of large burial depth， developed reef-flat facies， poor matrix properties， widespread development of natural fractures， and strong heterogeneity. The challenge is to construct three-dimensional geological modeling of such strongly heterogeneous dual-medium reservoirs. We divided the reservoir modeling object into two major media： matrix and fracture. Based on single well interpretation data and seismic wave impedance data， the matrix model was established by using well-seismic combination， step-by-step facies control， and multi-trend fusion probability constraint volume construction. According to the idea of multi-scale and multi-stage modeling， the entropy weight method combined with expert experience evaluation was used to construct the spatial distribution constraint volume of fracture through the integration of mechanism-geology-seismic data， as well as tectonic stress fields， distances to the fault， and seismic sensitive attributes of fractures. Under the constraints of the constraint volume， the fracture model was constructed by the discrete fracture network modeling. The numerical simulation of the gas reservoir was conducted on the established matrix-fracture model. The historical fitting rate of each well reaches 90%， and the fitting error is controlled within 20%， indicating a high fitting accuracy of the model.