Petrology Characterisitcs And The Influence On The Reservoir Quality Of The Sandstone In Taiyuan Formation, The Northeastern Of Ordos

Ordos basin is the second largest sedimentary basin on land in China which possesses abundant oil and gas resources and has bright prospect in oil and gas exploration. It has been becoming one of the important tactical area in oil and gad exploration in China. The northeastern of Ordos basin is one important gas production area in Ordos basin. In Paleozoic group, Shanxi formation, Shihezi formation, Shiqianfeng formation and Taiyuan formation are main production formation in the area. However, the reservoir is characterized with low porosity, low permeability and strong anisotropic. Moreover, the research degree of Taiyuan formation reservoir in the earth-north Ordos basin is low, all this brings more difficulty to oil exploration and exploitation in the area. It is specially important to find petrology characteristic and the forming and controlling factor of the highly effective sandstone body to provides the basis for forecasting the advantageous reservoir and its distribution.Paper in view of the petrology characteristic in Permian clastic rock reservoir in northeast Ordos basin, on the basis of analysis in doors, combined with the petrology and sedimentary theories, by means of various analytical techniques including conventional analysis of the core, analysis of capillary pressure, examination for resin-impregnated thin sections under a microscope, scanning electron microscope, et al, discusses the influence of petrology characteristic, autogenetic mineral and dissolution on reservoir quality.The primarily rock types of Yaiyuan formation are lithic sandstone, lithic quartzarenite and quartzarenite, but lacking feldspar sandstone, coarse grain size, locking feldspar and riching quartz, high composition maturity and poor structural maturity are the characteristics of Taiyuan formation reservoir sandstone. Reservoir sandstone has much matrix, and the average content achieves 10%. It mainly constitutes by hydromica, volcanic material, nud-iron material. It is the main factor that causes the porosity and permeability reduced, strong anisotropic in the reservoir. The reservoir sandstone has the medium autogenetic mineral content, mean value about 9%, mainly by the carbonate, the autogenetic quartz and the autogenetic clay mineral like illite, kaolinite is composed. It has big influence to the reservoir.Reservoir space are mainly secondary dissolution pores, including lithic dissolution porosity, intergranular dissolution porosity, mineral intercrystal porosity, feldspar dissolution porosity, The primary porosity is poor. The Taiyuan formation coal stratum produces acidic fluid and it dissolve the component of aluminosilicate mineral. It is the main origin of reservoir sandstone secondary porosity in the area...