川东北元坝地区三叠系飞仙关组鲕粒滩暴露标志的识别与地质意义  

Exposure Indications of Triassic Feixianguan Oolitic Beach Reservoir in Yuanba Area, Northeast Sichuan Basin:Recognition and Geological Implication

作　　者：刘雁婷[1] 傅恒[2] 陈骥[3] 李秀华[2] 曹竣锋[4] 

机构地区：[1]中国石化勘探南方分公司研究院 [2]成都理工大学能源学院 [3]中国石油西南油气田公司 [4]成都地质矿产研究所

出　　处：《海相油气地质》2014年第1期27-34,共8页Marine Origin Petroleum Geology

基　　金：中国石化股份有限公司重点研究项目"元坝地区长兴组-飞仙关组储层描述与预测"(编号:P09024)部分研究成果

摘　　要：四川盆地东北部元坝地区下三叠统飞仙关组储层主要为台地相鲕粒滩灰岩沉积。以研究区6口井岩心观察描述、15块岩心薄片及200块岩屑薄片鉴定为基础,结合扫描电镜及电子探针等分析手段,识别出元坝地区飞仙关组鲕粒灰岩成岩过程中的五种暴露标志:大气淡水方解石胶结物、溶蚀现象(鲕粒内溶孔充填淡水方解石)、含砾屑鲕粒灰岩(砾屑为海滩岩的破碎产物)、渗流黏土及渗流粉砂、褐铁矿化现象。综合区域地质及构造演化,认为飞仙关期二时末期海平面下降,使原沉积区暴露地表,经受大气淡水淋滤和溶蚀。这些暴露现象可作为识别碳酸盐岩层序界面的重要标志,也可以对精细层序的划分进行印证。暴露溶蚀作用易形成大量的次生孔隙,有利于优质储层的形成。Lower Triassic Feixianguan reservoirs mainly consist of platform oolitic beach limestone in Yuanba area in thenortheastern part of Sichuan Basin. On the base of macroscopic observation of core and lithic thin sections from 6 wells,combining with the analysis of SEM and EP, five exposure indications can be recognized in wide-distributing Feixianguanoolitic limestone during diagenesis： 1） meteoric freshwater calcite cementation, 2） dissolution （filling freshwater calcite withinoolitic dissolution pores）, 3） gravelly oolitic limestone （gravels are the broken beach rock）, 4） vadose clay and silt and 5）ferritization of ooids. Combined with the characteristics of regional geological and tectonic evolution, it is shown that sea leveldecline during the end of Feixianguan 2 Member sedimentation had made the primary sedimentary region expose to surfaceand undergo meteoric freshwater leaching and dissolution. Contributing to exposure and dissolution, a great amount ofsecondary pores develop increase which plays an important role in constructing excellent reservoirs. These exposure indicationscan be also used to recognize the sequence interfaces in carbonate rock and confirm the division of fine sequences.

关 键 词：四川盆地 元坝地区 下三叠统 飞仙关组 碳酸盐岩储层 鲕粒滩相 暴露标志 

分 类 号：TE121.32[石油与天然气工程—油气勘探]