Using Curvature Attributes to Identify a Carbonate Paleokarst System in the Ordos Basin

The Ordovician carbonate rock layer is one of the major Lower Paleozoic prospecting targets in the Ordos Basin. The gas distribution in this basin is closely related to the spread of Ordovician karst. Previous research mainly focused on weathered karst on the top of the Ordovician layer. The subsequent carboniferous sediments that deposited on the larger missing part of the Ordovician strata are thicker than its peripheral zones. It is clearly concave and can be identified by the time difference between the top and bottom of Carboniferous Strata in seismic section. In 3D seismic research on the Sulige-C block, by calculating time surface curvature and volumetric curvature attributes, we detect a collapsed paleokarst system differ from the weathered crust. The carboniferous sediment has an almost similar thickness. Calculations of surface curvature and volumetric curvature indicate that the most positive curvature signals reflect the flanks and edges of paleokarst solution collapse, while the most negative curvature signals reflect the thalweg. Volumetric curvature can help to trace the range of paleokarst solution collapse.