Abstract: Logging data and lithological analyses of the tidal-flat depositsin the 2^nd member of the Taiyuan Formation(D-17 wellblock)in the Daniudi gas field revealed three sedimentary microfacies:mainsandbar,sandbar flanking and overlain sandbar flanking-.A response-template of sedimentary micro-facies-lithofacies-logging facies-physical property-heterogeneity-gas test was also established.Correlation shows that the main sandbar is mainly gravel-bearing quartzose laterite and lithic quartz sandstone,corresponding to smooth-box type logging curves;and thelatter two are mainly medium-to fine-grained lithic sandstone and quartz sandstone,corresponding to dented box-and bell-shaped or funnel-shaped logging curves.Regionally,two belts were identified based on sand body assemblage types:sand body belt consisting main sandbar and sand body belt consisting sandbar flanking.The former is 6-8 km wide,and has an average thickness of 14.5 m,an average net-to-gross ratio of 0.53 and an average permeability of 0.48×10^-3 μm².The latter is 4-6 km wide and has an average thickness of 10.56 m,an average net-to-gross ratio of 0.36 and an average permeability of 0.36×10^-3 μm².The former with its well developed and widely distributed sand bodies is considered to be a better development target as it has better physical properties and strong heterogeneity and good gas testing results.

Key words: heterogeneity, sand bar, tidal-flat, high-quality sand body, Taiyuan Formation, Daniudi gasfield