广西北部湾北缘晚古生代—新生代油气资源潜力探讨

Study of oil and gas potential resources of the late Paleozoic to Cenozoic strata in the north of Beibu Gulf, Guangxi

通过野外地质剖面调查、丈量和室内烃源岩样品的有机地球化学测试，完成了广西北部湾北缘烃源岩岩石类型、地层厚度、分布的勘查、烃源岩的有机地球化学特征分析和综合评价。研究表明：广西北部湾北缘烃源包括了海相沉积的碳酸盐岩和湖相沉积的泥页岩两大类，海相碳酸盐岩烃源岩TOC含量分布范围为5．26％～0．001％，平均含量为0．41％，有机质类型以I型为主，少量为II型；母质来源为海洋低等浮游生物，藻类。艮（％）分布范围1．32％～4．78％之间，有机质热演化大多处于过成熟阶段，极少数为高成熟阶段。湖相泥页岩烃源岩主要分布古近系中，TOC含量分布范围为14．82％～0．07％，平均值为4．04％。有机质类型为III型和I型，艮分布范围为0.37％～0．41％，有机质热演化处于未成熟阶段。古近系那读组、二叠系合山组和石炭系寺门组为北部湾北缘最具生烃潜力的地层。

Through geological outcrop survey, measuring and geochemistry analysis on source rocks. We worked on types, thickness, distribution, organic characters and synthesized evaluation of source rock forma- tion of north Beibu Gulf in Guangxi. The research show that it is two categories that the source in the north of Beibu Gulf including carbonate rock of marine deposit and shale of continental deposit, the total organic cabon （TOC） content of the marine carbonate hydrocarbon source rock ranging from 5.26% to 0.001%, average con- tent amount to 0.41%. The main type of organic matter is type I , a few belongs to type II. The source is from both marine plankton and algae. The vitrinite reflectance （Ro） ofkerogen ranges from 1.32% to 4.78%, the or- ganic matter evolution mainly amount to post-maturity stage, very few is in high maturation. The hydrocarbon source rocks of mud shale of continental deposit are mainly distributed in the tertiary stratum, the total organic cabon （TOC） content ranging from 14.82% to 0.07%, averagely 4.04%. The main type of organic matter istype I and type III, the vitrinite reflectance （Ro） ranges from 0.37% to 0.41%, the organic matter evolution is in immature. The most hydrocarbon potential formation of the North of Beibu Gulf in Guangxi are the Naudou Formation of Paleogene, the Heshan Formation of Permian and the Simen Formation of Carboniferous.