湖相烃源岩原始有机质恢复与生排烃效率定量研究 ——以东营凹陷古近系沙河街组四段优质烃源岩为例

在烃源岩沉积有机相精细划分的基础上,优选东营凹陷古近系沙河街组四段的优质烃源岩样品,建立了完整的自然演化地球化学剖面,并应用物质平衡法,开展了原始有机质恢复和生排烃效率定量计算。计算结果表明,沙河街组四段主力供烃区间内的优质烃源岩具有高生排烃效率和原始有机质丰度恢复系数,其中深层高过成熟阶段排烃效率可达70%~80%,原始有机质丰度恢复系数可达1.5~2.0,较以往资源评价中采用的数值有较明显提高。据该结果推算,东营凹陷沙河街组四段的总排烃量总体上将有一定程度的提高,其中中浅层烃源岩的资源贡献有所降低,而深层烃源岩的资源贡献有较大幅度升高,主力烃源岩埋藏深度有下沉的趋势,这预示着深层具有丰富的资源基础和勘探前景。研究成果对于济阳坳陷乃至整个渤海湾盆地的油气资源潜力再认识和深层油气藏勘探具有重要的指导意义。

Recovery of Original Organic Matter Content and Quantitatively Study of Generation and Expulsion Efficiency for Lacustrine Hydrocarbon Source Rocks: A Case Study of the Excellent Source Rocks of the Palaeocene E2-3s4, Dongying Sag

On the basis of sedimentary organic facies study and source rocks fine classification, we select the excellent source rocks of different maturity from the 4th Member, Shahejie Formation, Palaeocene (E2-3s4) and set up a natural evolutionary geochemistry section. Using material balance method, the original organic matter contents are recovered and the petroleum expulsion efficiency is quantitatively studied. According to the quantitatively calculation, the expulsion efficiency of the excellent source rocks in principal hydrocarbon supplying stage are high and can reach 70%~80%, and the original organic matter content recovery factor of the deep zone can reach 1.5~2.0. These results will bring important influence to the total resource and resource distribution evaluation. The total hydrocarbon content generated and expelled will be higher than previous study, with the source rocks in the deep zone will be significantly higher than before. These result imply that the principal effective hydrocarbon source rocks will be more deep than previously believed. So the study has great significance to the resource reevaluation and deep zone oil and gas reservoir exploitations.