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东濮凹陷杜寨-桥口-白庙地区油气资源丰富,油气水关系复杂,勘探难度大。分析结果表明,天然气甲烷含量一般在80%～90%之间,甲烷δ13C1在-36.1‰～-39.9‰之间;距兰聊断层较远的井,40Ar/36Ar比值一般小于590,3He/4He比值为n×10-8,呈现典型的油型气特征;在兰聊断层附近的井,40Ar/36Ar比值一般大于1000,3He/4He比值为n×10-6,均表现为较高的值,并且40Ar/36Ar与3He/4H呈正相关关系,表明有幔源惰性气体的混入,这些井的甲烷碳同位素比油型气偏重5.0‰～8.0‰,比煤型气偏轻4.0‰～7.0‰。因此,兰聊断层附近的井,天然气以煤型与油型混合成因为主,部分井天然气可能为纯煤型气。凝析油特征表现为湖相地层生成的成熟度较高的油,根据地球化学特征可明显分为两组:一组以桥口东翼桥20、桥23与白庙地区的白16等井为代表,它们具有较低的伽马蜡烷指数,可能与葛岗集洼陷烃源岩有关;另一组是白庙主体,它们具有较高的伽马蜡烷指数和奥利烷指数,与前梨园洼陷烃源岩有关。研究认为,杜-桥-白地区天然气与凝析油为源岩热演化后期高温裂解的产物,形成的天然气藏具有多源、多阶、复合成藏的特征。
Duzhai-Qiaokou-Baimiao area in Dongpu Depression is rich in oil and gas resources, complicated in oil-gas-water relationship and difficult to prospect. The results show that the methane content of natural gas is generally between 80% and 90%, the δ13C1 of methane is between -36.1 ‰ and -39.9 ‰, and the ratios of 40Ar / 36Ar are generally less than 590 and 3He / 4He The ratio is n × 10-8, showing the typical characteristics of oil-gas. The ratios of 40Ar / 36Ar are generally higher than 1000 and 3He / 4He are n × 10-6 in wells near Lan-Lia fault, , And there is a positive correlation between 40Ar / 36Ar and 3He / 4H, indicating that mantle-derived inert gas is mixed in. The methane carbon isotopes of these wells are 5.0 ‰ -8.0 ‰ more than oil gas and slightly lighter than coal gas 4.0 ‰ -7.0 ‰ . Therefore, the wells and natural gas near the Lanliao fault are mainly caused by the mixture of coal type and oil type, and some of the natural gas may be pure coal type gas. The condensate oil is characterized by high maturity oil produced by lacustrine strata, which can be divided into two groups according to geochemical characteristics: a group of wells with East Wing Bridge 20, Bridge 23 and Baimiao Well , They have lower Gamma-Clay index, which may be related to the source rock of the GeGangji Sag; the other is the Baimiao main body, which have higher Gamma-Clay Index and Olytane Index, Related to the source rock of the former Liyuan depression. The study shows that natural gas and condensate in Du-Qiao-Bai area are the products of pyrolysis at the late stage of source rock thermal evolution. The gas reservoirs formed are characterized by multi-source, multi-stage and complex accumulation.