A New Fault Detection Method Based on Seismic Horizons and Its Application in Shale Reservoirs

Conventional fault detection methods based on the seismic amplitude discontinuity face challenges in shale reservoirs. Such methods generally cannot balance anti-noise performance and high sensitivity to small scale faults, thus leading to poor spatial continuity of identified faults. To solve this problem, this paper proposes a planar fault detection method based on the seismic horizons to make up for the deficiencies of amplitude-dependent approaches. This method is founded on the principle that the relative displacement of the same stratum on both sides of a fault plane is proportional to the local maximum standard deviation of the seismic horizon. The proposed method is implemented in three steps. Step1: Extract the horizon surface from 3D seismic data; Step 2: Calculate the local standard deviation of the extracted surface; Step 3: Extract fault features using a multi-scale vessel enhancement filtering algorithm based on the computed standard deviation. The proposed method has achieved promising results in a shale reservoir in the Sichuan Basin, China. Compared with traditional amplitude-based technologies, this method has more definite geological implications and enables more robust identification of planar fault characteristics. The final results can serve as supplementary evidence for classifying complex faults into different levels.