辽河拗陷东部凸起古生界油气地质条件与成藏模式

    Geological conditions and accumulation models of Paleozoic hydrocarbon in the Eastern Uplift of Liaohe Depression

    • 摘要: 近年来,辽河拗陷东部凸起多口钻井于古生界见到良好油气显示,展现了较好的勘探前景,但其油气成藏的主控因素与成藏模式尚不清楚,严重制约了油气勘探进程.为进一步探讨东部凸起古生界油气资源勘探潜力,综合利用露头、地震、探井及化学实验资料,分析古生界烃源岩、储层等成藏条件,落实了油气成藏主控因素,并建立了油气成藏模式.结果表明:辽河拗陷东部凸起发育石炭系—二叠系本溪组、太原组、山西组3套潜在烃源岩层系,暗色泥岩及煤层均具有较高的有机质含量;发育上古生界致密砂岩、下古生界碳酸盐岩风化壳2种类型储层;上古生界岩性气藏主控因素为储集条件,下古生界碳酸盐岩风化壳气藏主控因素为上覆烃源岩及岩溶储层展布;发育上古生界自生自储岩性气藏,下古生界风化壳上生下储气藏,上古生界、中生界次生气藏及新生古储油藏4种成藏模式.

       

      Abstract: In recent years, quite a few wells in the Eastern Uplift of Liaohe Depression have drilled significant hydrocarbon shows in the Paleozoic strata, revealing promising exploration potential. However, the main controlling factors and accumulation model for these hydrocarbons remain unclear, severely hindering further exploration. To better evaluate the exploration potential of the Paleozoic hydrocarbon in the Eastern Uplift, this study integrates data from outcrops, seismic surveys, exploration wells, and chemical experiments to analyze key conditions for hydrocarbon accumulation such as source rocks and reservoirs, and to identify the primary controlling factors and corresponding accumulation models. The results indicate that the Eastern Uplift develops three potential sets of source rocks, i.e. Carboniferous-Permian Benxi, Taiyuan, and Shanxi formations, in which dark mudstones and coal seams exhibit high organic matter content. Two main reservoir types, namely the Upper Paleozoic tight sandstone and the Lower Paleozoic weathered carbonate rock crusts, are identified. The accumulation of Upper Paleozoic lithologic gas reservoirs is primarily controlled by reservoir quality, whereas the formation of Lower Paleozoic weathered crust gas reservoirs is mainly governed by the distribution of overlying source rocks and karst reservoirs. Four hydrocarbon accumulation models are established: Upper Paleozoic self-sourced lithologic gas reservoirs; Lower Paleozoic weathered crust gas reservoirs with upper-source and lower-reservoir configuration; Upper Paleozoic and Mesozoic secondary gas reservoirs; and young-source-old-reservoir oil accumulations.

       

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