Abstract:

About the sedimentary facies of the Jia 2 Member，Jialingjiang Formation，Lower Triassic in Centre Sichuan，there exists a disagreement on tidalflat

deposition and nontidalflat deposition for many years.On the basis of fine core description，thinsection identification and logging analysis，according to the

analysis of sedimentary characteristics，such as sedimentary palaeogeographic background，lithology，sedimentary structures，sedimentary rhyme，palaeoclimate and digenetic

evolution，it is realized that tidal flat facies is not widly distributed in Jia 2 Member，Moxi gas field，but the restricted to evaporate carbonate platform facies in the

epeiric sea is common，and subtidal reducing environment is dominant.The depositional characteristics of similar tidalflat environment exist in the Jia22 B bed

only.It is recognized that the sedimentary facies in Jia 2 Member mainly include platform flat，grain shoal，interbank sea，semirestricted to restricted lagoon，

evaporative lagoon subfacies and so on.The Jia 21 Submember is mainly composed of the deposition of semirestricted to restricted to evaporate lagoon and

interbedded tempestite.The Jia 22 A Bed is characterized by the development of oolitic shoal microfacies.The Jia 22 B Bed is featured by the development of platform

flat subfacies.The sandsize intraclast shoal and evaporative lagoon subfacies are developed in the Jia 22 C Bed.By the analysis of a change of reservoir

porosity with microfacies，it is shown that the dolomite flat，sandsize intraclast shoal and oolitic shoal are favorable reservoir microfacies.

Key words: sedimentary facies, epeiricsea platform, Jia 2 member, Moxi gas field, Sichuan Basin