Facies and reservoir rocks at Cambrian inner platform (Sichuan Basin) and platform margin (Tarim Basin): Evidence from 3D seismic data

Significant hydrocarbons have been discovered in Cambrian strata of Sichuan and Tarim Basins, China. These Cambrian reservoir rocks, which are crucial for petroleum exploration, were deposited in a distinct carbonate platform setting, inner-platform in Sichuan and platform-margin in Tarim. Two 3D seismic surveys, GM in Sichuan and GC in Tarim, provide valuable data to characterize facies and reservoir architectures through seismic sedimentology and multiple discipline data. Modern analogs, such as San Andreas Fault system and the Florida Keys, aid in geomorphologic and facies interpretation, as well as analyzing the reservoir distribution in both basins. In the GM, facies include shoal crest, shoal margin, intershoal, and lagoonal settings. Reservoir quality of GM is enhanced by high-energy shoal crest and shoal margin facies and characterized by thick, well-developed grainstone with favorable porosity and permeability. Conversely, the GC exhibits a facies framework comprising middle ramp, outer ramp, and basinal deposits, where reservoir development is linked with tidalchannel-modified shoals, channel-mouth deltas in middle ramp, and slope fans transitioning into basin-floor fans in deeper-water settings. These findings have significant implications for hydrocarbon exploration and production strategies. The seismic sedimentological approach offers valuable insights for exploring analogous hydrocarbons in the carbonate systems worldwide.