Reservoir Sandstone Diagenesis of Memeber 6 to 8 in Yanchang Formation (Triassic), Xifeng Oilfield, Ordos Basin

Reservoir sandstone of Member 6 to 8 in Yanchang Formation (Triassic) in Xifeng oilfield of Ordos basin is typical of low porosity and low permeability, which has the characteristics of fine grain size, low compositional maturity, poor roundness and good sorting. Based on thin-section observation and analyses of c lay minerals, stable isotopes and physical property, this article takes researc h on diagenetic characteristics in Member 6 to 8 of Yanchang Formation, analyses their influence on reservoir physical property and determines diagenetic stage of reservoir sandstone. Meanwhile, this article indicates that the development o f high quality reservoir is dependent on the development of clay film, hydrocabo n emplacement grain dissolution in reservoir sandstone.