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随着鄂尔多斯盆地奥陶系天然气勘探工作的不断深入,中央古隆起东侧奥陶系马家沟组五段5亚段—马家沟组五段10亚段中组合天然气勘探取得了重要进展,但目前有关天然气成因与来源的研究还很薄弱。根据天然气地球化学特征、古油藏发育特征等分析结果,并结合天然气成藏地质背景,厘定了鄂尔多斯盆地中央古隆起东侧奥陶系中组合天然气的成因与来源。研究表明,鄂尔多斯盆地奥陶系中组合天然气为上古生界煤系烃源岩生成的煤型气与下古生界碳酸盐岩烃源岩生成的油型气的混合气,并以上古生界煤型气为主。现今气藏天然气组分中甲烷主要来自上古生界煤系烃源岩,上组合以及中组合少部分天然气的乙烷较多来自下古生界油型气,中组合大部分天然气乙烷及重烃仍来自上古生界煤系烃源岩。
With the deepening of Ordovician gas exploration in the Ordos Basin, significant progress has been made in natural gas exploration in the 5th member of Member 5 of the Ordovician Majiagou Formation in the east of the Central Gulohueou-Submember 10 of the 5th member of the Majiagou Formation, However, the current research on the causes and sources of natural gas is still weak. Based on the analysis results of natural gas geochemical characteristics and paleo-oil reservoir development features and combining with the geological background of natural gas accumulation, the origin and origin of natural gas in the Ordovician combination on the eastern side of the central paleohigh in the Ordos Basin are determined. The results show that the combination of natural gas in the Ordovician Ordos Basin is a mixture of coal gas generated from Upper Paleozoic coal measure source rocks and Lower Paleozoic carbonate source rocks, The world-based coal-based gas. Currently, methane in the gas components of the gas reservoirs mainly comes from the Upper Paleozoic coal-measure source rocks. Most of the ethane in the upper and middle combinations is derived from the Lower Paleozoic oil-gas, which combines most natural gas ethane and heavy Hydrocarbons are still derived from Upper Paleozoic coal-bearing source rocks.