DISTRIBUTION CHARACTERS AND HYDROCARBON-GENERATING POTENTIAL OF BITUMEN OF SINIAN-LOWER PALEOZOIC IN SICHUAN BASIN

This paper systematically studies the sort,origin,distribution,capability of hydrocarbon-generating,and main gas-generating times of the bitumen of Sinian-Lower Paleozoic in Sichuan basin.Based on the whole rock polished surfaces configuration and optical characteristic,the bitumen is sorted five types.It has two origin kinds,one is original-in the bed bitumen which mostly distributed in the dark mudstone,fine sandy mudstone,the other is secondary-reservoir bitumen which mostly distributed in the carbonate reservoir rock.Bitumen distributed widely in Dengying formation,its content is higher,from depression (where account for 0.41%)to slope (0.93%～1.13%)and to uplift (2.4%～5.41%),which means higher content in Leshang-Longnusi Paleo-uplift.The Bitumen has high content in weathering zone and become less far from the zone.The Bitumen of Dengying formation of Sinian forms in middle Jurassic,its the main gas-generating time is early Cretaceous which is later than koregen.The Bitumen has strong capability of hydrocarbon-generating which can accumulate to middle gas field.