The Geochemical Characterization of Adsorbed/Occluded Hydrocarbons Inside Solid Bitumen in the Kuangshanliang Area of the Northwestern Sichuan Basin and Its Significance

The geochemical characterizations of adsorbed and occluded components of solid bitumen in the Kuangshanliang area of northwestern Sichuan Basin were studied by comparing the results of conventional extraction and mild oxidative degradation. The results indicate that the solid bitumen originated from Sinian–Cambrian ancient oil reservoirs. The main source of the parent material is lower-order aquatic deposited in a high-sulfur anoxic marine environment. Exposed solid bitumen suffered from severe biodegradation, altering the tricyclic terpane/pentacyclic terpane and (pregnane + homo-pregnane)/regular sterane ratios as compared to the earlier parent material.