东濮凹陷西南部晚古生代-早新生代烃源研究

东濮凹陷西南部有石炭系-二叠系和沙三段两套主力烃源岩，其生烃能力及对油气成藏的贡献影响着该区勘探层系和目标的评价，尤其是沙三段能否生气、气藏是否混源等存在不同的观点。应用碳同位素、稀有气体同位素、天然气组分、色谱-质谱等多种地球化学方法，进行了油、气源对比及烃源岩地球化学特征研究。研究认为，沙三段烃源岩有机质以Ⅱ₂型~Ⅲ型干酪根为主，丰度较高，为差-中等烃源岩；石炭系-二叠系烃源岩有机质以Ⅲ型干酪根为主、丰度高，为好-优质烃源岩。工区原油来自沙三段；沙三段烃源岩具有先生原油，再进入高成熟阶段生成具有重碳同位素特征的煤型气的特点，石炭系-二叠系烃源岩主要生成煤成气，两种气混合成为工区重要的天然气来源；两套烃源岩共同供烃的区带是该区最有利的勘探方向。

Study on Hydrocarbon Source Rock of Late Paleozoic-early Cenozoic in the Southwestern Dongpu Sag

There are two main groups of hydrocarbon source rocks in southwest Dongpu Sag, the Carboniferous-Permian and the third member of Shahejie Formation. Their hydrocarbon generation capacity and their contribution to hydrocarbon accumulation affect the evaluation of the exploration strata and targets in this area, especially since there have been differing opinions regarding whether the third member of the Shahejie Formation can produce gas, and whether the gas reservoirs are mixed-source. By using geochemical methods, such as carbon isotopes, rare gas isotopes, natural gas compositions, and chromatography-mass spectrometry, oil and gas sources were compared and the geochemical characteristics of the source rocks were studied. The study shows that the organic matter in the source rocks of the third member of Shahejie Formation are dominated by Type Ⅱ₂ to Type Ⅲ Kerogen with high abundance and are poor-moderate grade source rocks, while the organic matter in the Carboniferous-Permian source rocks are dominated by Type Ⅲ Kerogen with high abundance and are good quality source rocks. The crude oil in the area comes from the third member of Shahejie Formation, where the source rocks are characterized by generating oil first and then entering a high-maturity stage to produce coal-type gas with heavy carbon isotopes. The Carboniferous-Permian source rocks mainly produce coal-formed gas. These two types of gas mix and become important natural gas sources in the area. The two groups of hydrocarbon source rocks are the most favorable exploration sources in this area.