四川盆地震旦系-下古生界沥青产烃潜力及分布特征

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

从分类、成因、分布、生烃能力及主生气期等方面对四川盆地震旦系—下古生界的沥青进行了系统分析。主要分布在泥页岩中的原生—同层沥青和在碳酸盐岩储集层中的后生—储层沥青,按全岩光片形态及光性特征可分为5种类型。在层系上以灯影组沥青含量较丰富,在区带上以乐山—龙女寺古隆起分布多,从坳陷带(0.41%)、斜坡带(0.93%～1.13%)、隆起部(2.4%～5.41%)沥青含量逐渐升高;沥青在古风化面含量最高,向下沥青含量相对降低。震旦系灯影组沥青形成于中侏罗世,主生气在早白垩世,晚于干酪根,生烃能力强力,可形成中型气田规模。

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.