At present,the study of sedimentary microfacies has been carried out on the second member of the Triassic Xujiahe Formation(Xu2 member)in the western Sichuan region,but there are differences in the rock facies characteristics and sedimentary cycles under different microfacies backgrounds.To more accurately characterize the rock facies characteristics,it is indicative significance for favorable reservoirs.Based on the petrological characteristics of continuous cuttings and core thin sections identification,a more precise sequence of material composition,rock facies type,and sedimentary microfacies evolution is established in the Xu2 member using geological methods and cluster analysis techniques,combined with well-logging data and other information.The sand body in the Xu2 member can be divided into 6 rock facies,and 16 sedimentary cycles of underwater distributary channel-inter distributary bay and underwater distributary channel-estuarine bar are identified.Statistics show that the lower part of the underwater distributary channel has better physical properties in rock facies A1 and A4,so the physical properties of the lower part of the underwater distributary channel are usually higher than those of the upper part and are generally better than those of estuary dam.The physical properties of the middle subsegment in the second section are the best,followed by the upper subsegment and the lower subsegment.The physical properties of underwater distributary channels are generally better than those of estuarine dams.A certain correlation exists between the changes in physical properties and cycle and rock facies.A1 and A4 rock facies developed in the middle and lower part of underwater distributary channels are more likely to form favorable reservoirs.
cluster analysismaterial compositionlithofacies combinationsedimentary cyclethe second member of Xujiahe Formationwestern Sichuan region
NETL
NSTL
维普
万方数据
