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为了研究六盘山盆地下白垩统马东山组的页岩气勘探潜力,对马东山组的泥页岩样品进行了一系列储层物性、孔隙结构和有机地化的分析试验。研究表明:六盘山盆地马东山组泥页岩有效厚度较大,平均121.5m,脆性矿物含量高,在80%以上;在孔隙特征方面,该套泥页岩主要发育微小孔,发育少量微裂缝,孔隙度均值为3.97%,平均可动流体饱和度为2.76%;在地化特征方面,该组泥页岩总有机碳含量平均1.01%,有机质类型以Ⅱ型干酪根为主,镜质体反射率平均0.94%。综合考虑泥页岩有效厚度、有机质丰度、有机质类型、热演化程度和孔隙特征等因素,六盘山盆地马东山组具备页岩气富集与成藏的条件,并可优选出两个页岩气勘探有利区:分别是海原凹陷东部有利区和固原凹陷中部有利区。经计算,两个勘探有利区的页岩气资源总量约为0.364亿m3。
In order to study shale gas exploration potential of the Lower Cretaceous Madongshan Formation in the Liupanshan Basin, a series of reservoir physical properties, pore structure and organic geochemical analyzes were carried out on the shale samples from the MaDongshan Formation. The results show that the shale in the Maodongshan Formation in the Liupanshan Basin has a large effective thickness of 121.5 m with a high content of brittle minerals above 80%. In terms of pore characteristics, the mud shales mainly develop micro-pores and a small number of micro-cracks , The average porosity is 3.97% and the average mobile fluid saturation is 2.76%. In terms of geochemical characteristics, the total organic carbon content of shale in this group is 1.01% on average, the type of organic matter is mainly type Ⅱ kerogen, The average reflectivity is 0.94%. Considering the effective thickness of shale, the abundance of organic matter, the type of organic matter, the degree of thermal evolution and the characteristics of pores, the Matangshan Formation in the Liupanshan Basin has the conditions for shale gas enrichment and reservoir formation. Two shale Beneficial areas for gas exploration: favorable areas in the eastern Haiyuan depression and central favorable areas in the Guyuan depression, respectively. It is calculated that the total amount of shale gas resources in the two exploration favorable areas is about 364 million m3.