Sinian-Ordovician hydrocarbon-source rock correlation and hydrocarbon-generation evolution in central and southeastern Sichuan,China

Geology, stratigraphy, drilling, logging, biomarker studies and apatite fission tracks were used to study Sinian- Ordovician mudstone and reservoir bitumen extracted from exploration wells located in central and southeastern Sichuan. This analysis confirms the source rocks were located in a reducing sedimentary environment, with organic matter such as bacteria and algae. The bitumen found in Sinian-Ordovician reservoirs in central Sichuan and Sinian reservoirs in southeastern Sichuan were mostly derived from Cambrian mudstones. The reservoir bitumen found in Cambrian rocks in southeastern Sichuan are from a mixed Cambrian-Silurian source. The apatite fission track combined with the Easy% Ro model were used to reconstruct the hydrocarbon-generation history of Cambrian source rocks in the Dingshan 1 well in southeastern Sichuan. The comparison between the Gaoke 1 well located in central Sichuan and the Dingshan 1 well demonstrates the maturation time and oil and gas generation stage from Cambrian source rocks in southeastern Sichuan is younger than the source rocks from central Sichuan. The source rock formations underwent tectonic uplift and reburial for secondary hydrocarbon-generation. The research methods provided can assist in oil exploration of deep and old hydrocarbon-bearing strata with a multi-stage evolution and tectonically superimposed features in the Chinese Qinghai-Tibet plateau basin, or similar basins worldwide.