鄂尔多斯盆地东北缘神府区块上古生界致密砂岩成藏特征

Accumulation characteristics of Upper Paleozoic tight sandstone in Shenfu block,northeastern margin of Ordos Basin

为进一步拓展鄂尔多斯盆地东缘致密气勘探前景,在区域烃源岩、储层、盖层和运移输导体系分析基础上,结合流体包裹体测试,开展了神府区块石炭系—二叠系(C—P)致密气成藏条件研究。结果表明:主力煤层厚度较大且分布稳定,较大的生烃强度构成成藏的基本条件;储层整体呈现低孔低渗特征,以残余粒间孔和粒内溶孔为主要储集空间;C—P内部广泛发育的泥岩具备良好的封盖能力;流体包裹体均一温度指示1期持续性成藏;可划分出源内、近源和远源等3种储盖组合模式。不同层位源储配置的差异控制着不同成藏模式的形成。该研究成果进一步拓展了鄂尔多斯盆地油气勘探开发前景,为研究区及类似致密气田勘探提供了理论基础。

In order to further expand the exploration degree of tight gas in the eastern margin of Ordos Basin,based on the analysis of regional source rock,reservoir,caprock and hydrocarbon transport system,combined with fluid inclusion test,the tight gas accumulation conditions of Carboniferous-Permian in Shenfu block were studied.The results show that the main coal seams are thick and stable,and the better hydrocarbon generation intensity constitutes the basic conditions for accumulation.The reservoir is characterized by low porosity and low permeability,with residual intergranular pores and intragranular dissolved pores as the main reservoir space.The mudstone widely developed in Carboniferous-Permian has good sealing capacity.The homogenization temperature of fluid inclusions indicates the first stage of continuous reservoir formation,and three reservoir-cap assemblage models,namely,within source,near source and far source,can be divided.The difference of source reservoir configuration in different layers controls the formation of different accumulation models.The related achievements and understanding further expand the prospect of petroleum exploration and development in Ordos Basin,and provide a theoretical basis for oil and gas exploration in the study area and similar tight gas fields.