Abstract：
Fault zones have always drawn attention from the industry, and the performance of a quantitative interpretation of the fault interior structure on seismic data has remained as a big challenge. In this work, we focus on quantitatively populating the heterogeneity of the fault interior structure in a three-dimensional space on seismic data. To realize this goal, we take the South Wuerxun sub-depression in Hailar Basin as an example of a faulted basin. First, based on a heterogeneity analysis using the drilling and logging information from wells, we establish fault zone geologic models and perform seismic forward modeling to determine the relationship between different fault zone models with different fault dips, internal fillings, and P wave responses. Next, the fault interior structure index (FIS) is constructed, and the response features on the FIS from the fault facies and the host rock are observed. Finally, the FIS is applied to perform the quantitative interpretation and prediction of the heterogeneity in the FIS on seismic data. The results show that the FIS response from the fault zone is higher than that of the host rock in plane, indicating that the former is quantitatively separated from the surrounding host rocks. The FIS values greater than 26 represent the feedback from the fault facies, whereas those less than 26 represent the response from the host rocks. The FIS shows segmented features in the strike, banded in dip on plane. On the slip surface, the FIS indicates the shale smear zone and the location where low-graded and small-scaled faults are densely developed. The heterogeneity prediction result is proven by oil and gas exploration activities. The study results imply that the FIS could indicate a favorable path of the hydrocarbon migration in the fault zone and evaluate the fault sealing parts. The method can explore the quantitative characterization of fault facies and has essential popularization and application values in similar geological application fi elds, including hydrocarbon exploration, development of faulted reservoirs, and geological engineering evaluation related to faults.
2024, Vol. 21 
