Mapping Subsurface Fault Networks by Using 3D Seismic Attributes: A Case Study in Sichuan Basin, China

Abstract:

The structure of a subsurface network of faults, which has a significant effect of fluid flow and seismic hazard, is inherently difficult to recognize and map. For the mapping of the fault system within a carbonate reservoir in western Sichuan Basin, China, we used a 3D seismic survey that covers an area of 318.5 km². We applied the 3D attributes of curvature, edge detection, dip and dip azimuth (Chopra & Marfurt, 2007). We focused on the Leikoupo Formation, at ~6 km depth, in the south limb of an anticline adjacent to Longmen Shan thrusting range. The mapped attributes (image below) display a network of two sets of faults in almost orthogonal pattern, striking northeast and northwest with length range of 1-10 km. These faults network diminished into underlaying unit of anhydrite. We envision that the fault network reflects the integrated brittle-ductile deformation of the carbonate and anhydrite stratigraphic unit due to the shortening imposed by the Longmen Shan range in the west.