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基于非常规气理念,以鄂尔多斯盆地东部奥陶系马家沟组马五_(1+2)亚段碳酸盐岩储层为例,采用露头、岩心、铸体薄片、孔隙度、渗透率、同位素和试气成果资料综合分析的方法,重新认识和评价其含气潜力。结果表明,储层以泥粉晶—粗粉晶白云岩为主,渗透率小于0.1×10~(-3)μm~2的储层占80%以上,孔隙类型主要为裂缝—溶孔、裂缝—晶间孔,非均质性强,属于致密碳酸盐岩储层。气藏具有低丰度大面积分布、异常低压、无边底水、无自然产能、产水少等特点,属于碳酸盐岩致密气藏。天然气分布主要受控于大范围稳定分布的特殊的镶嵌式源储组合和平缓的单斜构造背景,勘探潜力较大,是海相碳酸盐岩天然气勘探的一种新类型。
Based on the unconventional gas concept, taking carbonate reservoir of Ma5 (1 +2) sub-member of the Ordovician Majiagou Formation in the eastern Ordos Basin as an example, we use outcrops, cores, cast thin sections, porosity and permeability , Isotopes and test results of a comprehensive analysis of methods to re-understand and evaluate the potential of its gas. The results show that the reservoirs are dominated by mudstone - coarse grain dolomite, and the reservoirs with permeability less than 0.1 × 10 ~ (-3) μm ~ 2 account for over 80%. The types of pores are mainly fissures - dissolved pores, cracks Intergranular pores with strong heterogeneity belong to tight carbonate reservoirs. Gas reservoirs are characterized by large area with low abundance, abnormal low pressure, no edge water, no natural productivity and little water production, which belongs to the tight gas reservoir of carbonate rocks. The distribution of natural gas is mainly controlled by a large range of stable distributed special source-reservoir combination and gentle monoclinic tectonic setting, with great potential for exploration. It is a new type of natural gas exploration of marine carbonate.