鄂尔多斯多旋回叠合盆地演化与天然气富集

Evolution and Natural Gas Enrichment of Multicycle Superimposed Basin in Ordos Basin

鄂尔多斯盆地是在早元古代结晶基底的基础上发育起来的大型叠合盆地,其演化过程主要经历了中晚元古代拗拉谷盆地发育期、古生代稳定克拉通盆地发育期、中生代类前陆盆地发育期及新生代周边断陷盆地发育期。盆地构造演化的多阶段性,从而造就了上下古生界两套烃源岩和多套储盖组合。叠合盆地由于其形成演化、沉积建造的多旋回性,因而油气勘探具有勘探难度大、勘探时间长、勘探潜力大的特点。鄂尔多斯盆地的天然气勘探从区域上来看,目前主要集中于盆地中东部地区;从层系上来看,主要集中于奥陶系顶部风化壳岩溶储集体系和上古生界河流、三角洲储集体系。随着勘探的进一步深入,在“甩出去,打下去”思想的指导下,从区域上来看,盆地西部、南部地区;从层系上来看,寒武系鲕粒灰岩、奥陶系马四段白云岩以及蒸发盐岩下伏白云岩将是今后勘探的新领域。

Ordos Basin is a large multicycle superimposed basin, developed on the basement of early Proterozoic crystalline basement. Itsevolution progress had undergone four developed stages,i.e. middle-late Proterozoic aulacogen basin , Paleozoic craton basin ,Mesozoic forelandbasin and Cenozoic fault-depression basin in its adjacent region. Due to multistages of basin evolution, two series of source rocks and manycombinations of reservoir-caprock are developed.With the multicycle of sedimentary structures and formation evolution, superimposed basinhas difficulty in exploration, long time needed for exploration, and large potential of exploration. From the regional, natural gas explorationshould be focusing on the central-eastern part of Ordos Basin. On the stratum, natural gas exploration should be eyed on the Ordovicianweathering crust and upper Paleozoic fluvial-delta reservoirs. With the development of exploration, on the guidance of ideas to deep and to area,west and south of the basin on the area, Cambrian oolitic limestone and Ordovician dolomite rock deposited in the 4th member of MajiagouFormation and dolomite under the sub-salt, will be the new targets of exploration in Ordos Basin.