淡水湖相页岩小层精细划分及地球化学特征——以四川盆地侏罗系大安寨段为例

通过岩性、电性、旋回特征以及页岩地球化学数据分析，对四川盆地侏罗系自流井组大安寨段湖相页岩进行了小层精细划分和资源潜力评价。大安寨段页岩自下而上划分为3个小层，其中大一三_c小层主要发育滨—浅湖相块状泥页岩，横向变化大，有机质类型主要为偏腐殖型的Ⅱ₂型干酪根，平均有机碳含量在1%左右，平均S₁含量为0.8 mg/g；大一三_b小层主要发育半深湖相页岩夹薄层介壳灰岩条带，厚度分布稳定，有机质类型主要为偏腐泥型的Ⅱ₁型干酪根，平均有机碳含量大于1.5%，平均S₁含量为1.18 mg/g；大一三_a小层主要发育浅湖相页岩夹中—薄层介壳灰岩，有机质类型主要为偏腐泥型的Ⅱ₂型干酪根，平均有机碳含量为1%～1.5%，平均S₁含量为1.21 mg/g。结合地质特征、资金、技术条件以及勘探成效，认为川中北部公山庙地区的大一三_a和大一三_b小层，可以作为湖相页岩油气先导试验区的工作对象。 

Stratigraphic division and geochemical characteristics of freshwater lacustrine shale: a case study of Jurassic Da'anzhai Section,Sichuan Basin

The fine division and resource potential evaluation of lacustrine shale in the Da'anzhai Section of the Jurassic Ziliujing Formation in the Sichuan Basin were made based on lithologic, electrical, cyclic characteristic and shale geochemical data. The Da'anzhai Section was divided into three sub-sections, Da 1, Da 1 3 and Da 3, from top to bottom. The Da 1 3 sub-section was further divided into three sub-layers, Da 1 3 a, Da 1 3 b and Da 1 3 c, from top to bottom. The Da 1 3 c sub-layer mainly developed shore-shallow lake block shale, with large lateral changes. The organic matter is mainly the humic type Ⅱ₂ kerogen. The average organic carbon content is about 1%, and the average Rock-Eval S₁ content is 0.8 mg HC/g rock. The Da 1 3 b sub-layer mainly developed semi-deep lacustrine shale with thin layers of dielectric limestone, showing a stable thickness. The organic matter is mainly type II₁ kerogen with partial gel type. The average organic carbon content is more than 1.5%, and the average S₁ content is 1.18 mg/g. The Da 1 3 a sub-layer mainly developed shallow lacustrine shale with normal and thin dielectric limestone. The organic matter is mainly type II₂ kerogen with partial gel type. The average organic carbon content is 1% to 1.5%, and the average S₁ content is 1.21 mg/g. Based on current geological characteristics, funds, technical conditions and exploration results, it was proposed to open up a pilot test area of lacustrine shale oil and gas in the Gongshan Temple area in central and northern Sichuan Province, and concentrate on the Da 1 3 a and Da 1 3 b sub-layers.