鄂尔多斯盆地陇东地区二叠系盒8下段致密砂岩储层特征

陇东地区是鄂尔多斯盆地上古生界天然气勘探的新区带,二叠系下石盒子组盒8下段气层组是其主力产气层,该区沉积、储层和成藏等方面具有一定的复杂性,天然气勘探研究程度较低.结合测井资料、岩心观察、铸体薄片、物性等资料,对鄂尔多斯盆地西南地区二叠系下石盒子组盒8下段储层的岩石学特征、物性特征、孔隙结构特征进行研究,探讨了影响储层...

Reservoir Characteristics of Permian Lower He 8 Member in Longdong Area,Ordos Basin

The Longdong area is a new natural gas exploration zone in the Upper Paleozoic Ordos Basin. The Permian Lower Shihezi Formation (lower He 8 gas member) is the main gas-producing layer. The local deposition, reservoir and accumulation are relatively complex, and the level of understanding in the natural gas exploration is relatively low. Combining logging data, core observation, thin-section, physical properties and other data, we investigated the petrological characteristics, physical properties, and pore structural characteristics of the lower He 8 reservoir of the Lower Shihezi Formation in the southwestern Ordos Basin, and we discuss the main controlling factors on the reservoir performance. The results show that the reservoir sandstones of the lower He 8 are dominated by quartz sandstone and lithic quartz sandstone. Arkose content is low, suggestive of a high-energy and distal-source environment. During diagenesis, sandstone reservoirs may have undergone intense compaction and pressure dissolution, and the clastic particles and lithic fragments are interlocked with each other, accompanied by different degrees of quartz regrowth, and the disappearance of large number of primary intergranular pores. The pore types include mainly micro-sized intragranular pores and rock chip-dissolved pores. The reservoir physical properties are controlled by both the sedimentary facies and diagenesis. Sedimentary facies fundamentally control the reservoir physical properties. The sand-body structure has an important impact on the reservoir physical properties. The physical properties of the cut-type single sand-body are relatively good, followed by the spliced sand-body, and then by isolated single sand-body. Compaction is the main reason for the densification of the layer physical properties. Hydromica is the primary factor for the densification of the reservoir due to cementation. The degree of reservoir dissolution is low and the improving effect on the reservoir quality is limited. Our results provide a reliable geological basis and scientific basis for the further exploration and development of the lower He 8 reservoir at Longdong.