Reservoir characteristics and comprehensive evaluation of Chang-8 member,Yanchang formation of Maling area in Ordos basin

Based on previous research results,combined with core analysis data,the research on reservoir characteristics and comprehensive evaluation of Chang-8 member,Yanchang formation of Maling area in Ordos basin has been carried out.The results indicate reservoirs from Chang-8 memberare mainly focused on the braided river delta sedimentary.The main reservoir sand body types are distributary channel,underwater distributary channel,mouth bar,crevasse splay and far sand dam.The lithology is mainly gray-celadon fine siltstone fine sandstone inter-bedded with thin siltstone and has petrology characteristics of low compositional maturity and textural maturity.The reservoirs are given priority to residual original intergranular pores,seldom to secondary pores,and it is typical low-porosity low-permeability.Based on reservoir characteristics,through parameters analysis of porosity,permeability,displacement pressure and median pore throat radius,the reservoir classification evaluation standards of this area have been established.In combination with grading standards of porosity and permeability,the reservoirs in this area have been evaluated to be good reservoirs from comprehensive analysis.