Member 2 Log Facies of Xujiahe Formation of Upper Triassic,Sichuan Basin

The Petrochina Southwest Oil and Gasfield Company has considered the Upper Triassic in the Sichuan basin as important supporting strata,where the distribution of oil and gas is controlled by the sedimentary facies.The analysis of log facies plays an increasingly important role in the identification of sedimentary facies and sand body.Depending on the basic elements of logs such as shape,amplitude,and contact relationships,5 kinds of log facies,namely campaniform,infundibuliform,box like,dactyloid,linearis,have been identified.Through demarcation of log facies with core data,the functional relationships between log facies and sedimentary facies have been established.The distributing graph of the sedimentary facies of member 2 of Xujiahe Formation is drawn on the basis of the comprehensive analysis of the log facies of individual wells,the correlation of profiles and the areal study.In this graph,three kinds of sedimentary facies are recognized,namely alluvial fan,delta and lake,the distribution of which are controlled by 6 provenances.Because of intensive tectonic movements and sufficient supply of deposits,the alluvial fan deposits and delta deposits become widespread,while lake deposits are limited in distribution.