CHARACTERIZATION AND MODELING OF NATURAL FRACTURES IN CARBONATE RESERVOIRS BASED ON DIGITAL OUTCROPS

Structural fractures are important seepage channels and reservoir spaces of deep carbonate reservoirs, but their distribution has strong heterogeneity. At present, there is no effective technical method to solve the problem of quantitative characterization of fractures. The data of typical geological outcrops in the field are collected by UAV tilt photography, and the digital model of reservoirs and fractures in the outcrop area is established. On this basis, outcrop fracture identification and quantitative description of fracture parameters are carried out. Based on the research results of outcrop fractures, a multi-scale fracture hierarchical modeling idea is proposed. For large and medium-scale fractures, deterministic modeling method and collaborative modeling method under multiple constraints are adopted respectively. Facing the complex problem of small-scale fracture modeling, the multi-element information fusion method is used to fuse the fault strike model, the distance to the fault model and the formation curvature model to establish a small-scale fracture development probability volume and build a small fracture development model. Finally, the multi-scale fracture model is fused according to the development probability to construct the outcrop prototype geological model. The research results of outcrop prototype geological model are applied to the modeling of underground reservoir, and the multi-scale fracture network model of reservoir is constructed. The modeling results are in good agreement with the single well fracture interpretation and production data, and the large-scale fractures are mostly developed around the large-scale fractures, which is in line with the existing understanding. It shows that the research method of outcrop prototype geological model can provide important research ideas and geological basis for underground reservoir fracture modeling, and improve the efficiency and accuracy of reservoir fracture modeling.