Reservoir Characteristics And Influencing Factors Of Chang 8 Oil Formation In Yanchang Formation Of Southwest Ordos Basin

Ordos Basin is an important oil-gas-bearing basin in china which possesses abundant oil and gas resources. The Chang-8 reservoir of Yanchang Formation is one of the target layer in this basin. This dissertation take four blocks, Shangliyuan,Heshui, Xifeng, Maling,as researsh objects,and in based on collecting previous research, carry out a systematic study to Chang-8 reservoir,including petrologic feature, provenance, sedimentary microfacies, pore structure, diagenesis, tectonic activities,etc, by utilizing casting lamella, scanning electron microscopy,core observation,X-diffraction,high-pressure mercury and other technical means,and,finally,summarize the influence factors of the reservoir properties and forming conditions of high quality reservoir.Study area is located in southwestern Ordos basin. Its provenance direction is mainly southwest, and sedimentary evolution strictly controlled by the facies,and deposition is the basis to determine reservoir properties. Under the lake background, study area develop a suite of delta front subfacies depositional systems which main characteristic is fine debris granularity, mostly fine sandstone, and are composed of feldspar lithic sandstone which have multiple interstitial material, and with relatively poor reservoir properties except Xifeng area.Sediments endured a strong lately transformation caused by diagenesis and tectonic. Primary intergranular pore is reduced to residual intergranular pore because of compaction; due to filling in pores and occupying reservoir spaces, the sediments deteriorate the reservoir properties. Denudation is an important and constructive diagenesis in study area,which generate large amounts of secondary pore.By studying, the characteristics of the reservoir are controled by sedimentary, diagenetic evolution and tectonic activity, and the development of quality reservoir is also similarly affected.