Ordos Basin Sub-county To Extend The Low Permeability Reservoirs Fine Long Evaluation Group

The exploration of low permeability reservoirs is very important in china.Chang6, Chang4+5, and Chang2sets sedimentary microfacies group distribution characteristics is analyzed based on sedimentary petrology, reservoir geology, logging geology, oil and gas geology theory, by the wild outcrop data, analysis showed that:1, the study area is a large regional west-dipping monoclinic, The top surface structure of Chang2-Chang6is similar.2The sandstone of Chang2reservoir formed in meandering river environment, The sandstone of Chang4+5and Chang6reservoir formed in The meandering river delta environment that can be subdivided into delta plain, delta front two sub-phases.3The pore types of study area including intergranular pores, feldspar dissolution holes, debris dissolved pore, laumontite dissolved pore, intergranular holes, etc.4The diagenetic stage are early diagenetic compaction of weak-weak and late diagenetic cementation zone A zone of dissolution, the general characteristics of reservoir performance of low porosity and low permeability.5The low permeability reservoirs controlled:①the reservoir development be controlled by sedimentary facies, the properties of underwater distributary channel sand bodies and delta-plain distributary channel sand reservoir are best, the center of the reservoir sand bodies relatively good reservoir properties to both sides gradually deteriorated.②diagenesis: compaction damage reservoir porosity and permeability, cementation to generate a variety of authigenic minerals filling the pore and throat; metasomatism and recrystallization of minerals affecting the reservoir properties by changing the structure of the rock; dissolution through the reservoir to increase the dissolution of the unstable component reservoir improving reservoir porosity and permeability. In a comprehensive analysis, favorable exploration target area is preferred based on the classified sandstone reservoir evaluation.