Diagenetic facies studies for the high-permeability reservoirs of He 8 section in Suligemiao Area,Ordos Basin

The sandstone reservoirs of He 8 section in Suligemiao Area were formed by vigorous diagenesis.This is the main reason that the reservoir heterogeneity is obvious.Generally,different sedimentary microfacies developed different types of cementation that controlled distribution and intention of secondary pore dissolved by acid water solution.Through studying sedimentary microfacies of He 8 reservoir and analyzing about 800 thin sections,diagenetic facies of He 8 reservoir are classified as seven types.The relationships among diagenetic facies and five types of sedimentary packing sequences are discussed.The result shows that the favorable diagenetic facies are net sandstone dissolvable face and greywacke face,corresponding braided river point bar microface and delta plain distributary channel microface respectively.Based on sedimentary spread and diagenetic facies upgrowth disciplinarian,the distribution of highpermeability reservoirs in Suligemiao and its external areas was predicted.