鄂尔多斯盆地上三叠统延长组四、五段泥岩生烃潜力评价

为了重新认识鄂尔多斯盆地上三叠统延长组长4 +5段湖相泥岩的生烃潜力 ,对其进行了有机地球化学综合研究和油源对比 ,利用单井盆地模拟恢复了其生烃史 ,并进行了生烃强度分析和生烃量计算 ,结果表明 :长4 +5段湖相沉积范围近 6× 1 0 4 km2 ,长4 +5段湖相泥岩有机质丰度较高 ,氯仿沥青“A”质量分数多数超过 0 .2 % ,有机碳含量和生烃潜量 S1+S2 分别在 0 .5 4 %～ 4.87%和 0 .5 8～8.0 8mg/g之间 ,属于中等到较好的烃源岩 ;长4 +5段湖相泥岩有机质类型以 型为主 ,泥岩样品热模拟烃产率达 447.2 6 mg/g TOC,具有很高的生烃潜力 .长4 +5段湖相泥岩生物标志物特征与中生界原油和长 7段泥岩相似 .长4 +5段泥岩 Ro值在 0 .5 8%～ 0 .96 %之间 ,现处于低成熟到成熟阶段 ,地史上距今 1 1 0～ 90 Ma处于生油窗阶段 ,最大生烃强度 40× 1 0 4 t/km2 ,期望生烃量 1 1 1 .1 3× 1 0 8t

Evaluation of Hydrocarbon-generating Potential of the Fourth and Fifth Member Mudstone of Yanchang Formation of Upper Triassic Series in Ordos Basin

Geochemical comprehensive research of the reservoir is carried out and oil source correlation is analyzed for further recognizing hydrocarbon-generating potential of lake facies mudstone of Chang 4+5 member. By basin modeling of single well its hydrocarbon-generating history is obtained. Hydrocarbon-generating intensity is analyzed and the hydrocarbon quantity generated from lake facies mudstone of Chang 4+5 member is computed. It is shown that the sedimentation of lake facies mudstone covers about 6×10 4km 2. It belongs to medium to better hydrocarbon source rock, which has higher organic matter abundance, its content of chloroform bitumem "A" generally exceeds 0.2%, and TOC and S 1+S 2 are at the range of 0.54%~4.87% and 0.58~8.08mg/g respectively. Therefore, the lake facies mudstone possesses quite high hydrocarbon-generating potential, whose organic matter is mainly typeⅡ, and hydrocarbon-generating quantity of simulated sample reaches to 447.26mg/g TOC. The biomarker character of Chang4+5 mudstone is similar to that of Mesozoic oil and Chang7 mudstone. The value of Ro of Chang 4+5 mudstone is 0.58%~0.96%, and it is in the stage of low mature to mature. The Chang4+5 mudstone is in oil-generating window 110~90Ma(b.p), the maxium of hydrocarbon generating intensity of it reaches to 40×10 4t/km 2, the expected hydrocarbon-generating quantity is 111.13×10 8t.