川西南地区上三叠统须家河组沉积相特征

层序地层划分对比及有利沉积相带研究，对川西南地区油气勘探开发具有重要意义。为此，通过岩心、地震及测井等资料的综合研究，认为该地区上三叠统须家河组地层可划分为4个三级层序、12个体系域，发育海湾、湖泊、辫状河三角洲和正常三角洲这4种沉积相类型及20余种沉积微相，有利储集砂体为三角洲（水下）分流河道及河口坝砂体。沉积砂体分布既有继承性，又有分异性，并随不同时期主物源的变化而发生迁移，砂体发育情况主要受构造、物源供给、古地貌等因素的控制。

SEDIMENTARY FACIES OF UPPER TRIASSIC XUJIAHE FORMATION IN SOUTHWEST SICHUAN BASIN

Sequence stratigraphic division and correlation and study of favorable depositional facies are of important significances for petroleum exploration and development in the southwestern Sichuan Basin. Based on comprehensive study of core, seismic and logging data, the Upper Triassic Xujiahe Formation in the study area is divided into 4 third order sequences, 12 system tracts, 4 types of sedimentary facies including bay, lake, braided river and normal delta, and over 20 sedimentary microfacies. Favorable reservoir sandbodies include delta (underwater) distributary channels and mouth bars. The distribution of sandbodies is characterized by both inheritance and differentiation, and they have migrated along with the change of major sources of sediments at different periods. The development of sandbodies is mainly controlled by structures, source of sediment and paleogeomorphology.