塔里木盆地北部三叠系及其找油意义

塔北三叠系主要分布于库车坳陷、阿瓦提-满加尔坳陷及塔北断块隆起的局部地区,沉积厚达1250—2000m。跃参1井、沙参1井和阿参1井的三叠系满加尔群经详细研究,可分为上、中、下三组和7个孢粉化石组合。在阿瓦提-满加尔坳陷中,由西向东三叠系的暗色岩增多、增厚,生油地化指标变好,并已进入低成熟阶段,沙参2井的原油中就有三叠纪孢粉化石。因而认为三叠系是塔北的比较重要的生油层,而塔北断块隆起及其南侧的阿瓦提-满加尔坳陷北缘背斜带,则可能是油气富集带。

TRIASSIC SYSTEM IN THE NORTH PART OF TARIM BASIN AND ITS OIL PROSPECTING

Triassic system is mainly distributed in Kuqa,Awat-Mangar depressions and locally in the north Tarim fault-block uplift.In the north part of Kuqa depression and the east part of Awat-Magar depression,Triassic sediments are found to be 2000m and 1250m thick respectively.Through a detailed investigation,the Triassic sediments revealed by wells of Yuecan-1,Shacan-1 and Acan-1 are termed the"Mangar Group"(Tmn).This group can be further divided into 3 formations and 7 sporo-pollen assemblages.Among them,dark rocks become thicker from west to east,accordingly their geochemical indices are more favourable for oil generation,and kerogen of which had reached low mature stage.Crude oil collected from well Shacan-2 contains Triassic sporopollon.Thus Triassic sediments in north Tarim are considerably important source rocks,and Mangar depression should be a favourable broad region for oil generation. The author suggests that north Tarim fault-block uplift located at the higher part between Kuqa and Awat-Mangar depressions,is favourable for oil accumulation and migration.Paleozoic anticlines existed in the fault-block uplift and in the northern margin of Awat-Mangar depression may be the hydrocarbon enrichment zones.