二连盆地洼槽分类及其油气勘探意义  

Classification of Sub-sags in the Erlian Basin and Its Petroleum Prospecting Significance

作　　者：曹兰柱 吴飘 侯读杰[2] 魏秀丽 郑荣华 CAO Lanzhu;WU Piao;HOU Dujie;WEI Xiuli;ZHEN Ronghua(Exploration and Development Research Institute,PetroChina Huabei Oilfield Company,Renqiu,Hebei 062550,China;School of Energy Resources,China University of Geosciences,Beijing 100083,China;Qingdao Institute of Marine Geology,Qingdao,Shandong 266071,China)

机构地区：[1]中国石油华北油田公司勘探开发研究院,河北任丘062550 [2]中国地质大学(北京)能源学院,北京100083 [3]青岛海洋地质研究所,山东青岛266071

出　　处：《现代地质》2022年第2期719-728,共10页Geoscience

基　　金：中国石油天然气公司重大科技专项(2017E-15)。

摘　　要：二连盆地已发现56个凹陷和21个凸起,每个凹陷按腾一段地层沉积中心的分割性可划分为2~3个洼槽。为开展洼槽地质分类及其与生烃潜力的相关性研究,通过对10个含油凹陷23个洼槽的地质和地球化学资料统计分析,发现各洼槽的古生界基底顶面(T_(g))最大埋深、洼槽面积、阿尔善组及腾一段沉积期间的古水体盐度分别对阿尔善组和腾一段两套烃源岩的最大总厚度及成熟度、面积、有机质丰度及类型存在控制作用。据此提出按照基底埋深、深洼带面积和阿尔善组及腾一段的古水体盐度特征将洼槽划分为高熟型、成熟型和低熟型3大类14小类。结合洼槽生烃潜力评价,认为富生烃洼槽总体属于高熟大中型洼槽和成熟大中型咸水洼槽,咸水洼槽具有更优越的源储条件,更有利于致密油勘探。由于高熟咸水洼槽在马尼特坳陷和乌兰察布坳陷更发育,在勘探选区上应优先考虑这两个坳陷内的洼槽。A total of 56 sags and 21 uplifts have been discovered in the Erlian Basin. Each sag consists of two or three sub-sags, according to the segmentation of sedimentation center in the Tenggeer Formation(1^(st)member). In order to study the geological classification and its correlation with the hydrocarbon generation potential of the sub-sags, the geological and geochemical statistical data from 23 sub-sags were analyzed. It is found the maximum burial depth of the Paleozoic basement surface, the sub-sag area, and the paleo-water salinity during the epoch of the Aershan and Tenggeer(1^(st)member) Formation have respectively controlled the maximum total thickness and organic matter maturity, area, organic matter abundance and type of the source rocks in the Aershan Formation and Tenggeer Formation(1^(st)member). Thus, we propose that the sub-sags could be divided into the highly-mature, mature, and lowly-mature class, and 14 sub-classes according to the differences of the maximum basement burial depth, deep sub-sag area, and paleo-water salinity of the two formation strata. Coupled with hydrocarbon generation potential assessment of 23 sub-sags, we consider that hydrocarbon-rich sub-sags generally belong to highly-mature large-medium sub-sags sub-class or mature large-medium salty sub-sags sub-class. We suggest that the salty or brackish sub-sags are more suitable for tight oil exploration, as they possess more advantageous source and reservoir conditions. As highly-mature saline sub-sags are better developed in the Manite and the Ulanqab depressions, priority of exploration area selection should be given to the sub-sags in these two depressions.

关 键 词：二连盆地 洼槽分类 基底埋深 湖盆咸化 生烃潜力 

分 类 号：TE121.1[石油与天然气工程—油气勘探]