3D geological modeling of fractured volcanic reservoir bodies in Block DX18 in Junggar Basin, NW China

The DX18 reservoir is composed of four mutually superimposed volcanic bodies and is a pore-fracture dual-media igneous reservoir. The fractures inside the volcanic bodies are mainly structural fractures with continuous distribution in space, and the continuity of fracture development positions is poor both vertically and horizontally. For the preparation of reservoir development scheme and further improving production well pattern, the fracture development and distribution characteristics are studied by 3D geological modeling. In view of the complexity of spatial structure of volcanic bodies, a body-controlled structure modeling is applied to describe the entire 3D shape of volcanic bodies. By integrating seismic data and logging interpretation, the relationship between various seismic attributes and fracture development zone is analyzed. Based on the analysis result above, a seismic-constrained modeling method which integrates the well data and seismic data is applied to establish the 3D property model for volcanic bodies. The fracture porosity model is constrained by seismic porosity data volume created by neural network processing, and the fracture density model is constrained by seismic dip volume. The later drilling and production performance proved that the main fracture development zones inside the volcanic bodies are accurately predicted and described by the seismic-constrained geological model and the coincidence ratio reaches 93.8%.