塔里木盆地满西地区寒武系台缘带分段演化特征及其对生储盖组合的影响

The sectional evolution characteristics of Cambrian platform margin in Manxi area of Tarim Basin and its differences in source-reservoir-cap combination conditions

满西台缘带位于塔里木盆地满加尔凹陷西缘,是寒武纪—奥陶纪以来持续发育的大型碳酸盐岩台地边缘。近年来,有多口井在该带见到良好的油气显示,但至今没有获得油气勘探突破,生储盖组合配置条件是制约寒武系台缘带油气勘探成功的关键。通过对台缘带地震反射结构特征和迁移叠置样式分析,将满西寒武系台缘带划分为3段,并对其进行了分段沉积演化分析,指出差异构造沉降和相对海平面变化是控制台缘带差异演化的主要因素。在台缘带分段沉积演化分析的基础上,探讨了满西台缘带分段生储盖组合配置条件的差异,指出北段(轮南地区)膏云岩覆盖的下寒武统缓坡滩生储盖组合配置条件优,是最有利的勘探区,南段(古城地区)致密灰岩覆盖的上寒武统台缘礁滩体生储盖组合条件次之,是较有利的勘探区。

Manxi platform margin is located in the western edge of the Manjiaer Depression,Tarim Basin.It has been a large carbonate platform margin since Cambrian-Ordovician.In recent years,rich oil and gas shows have been found in the wells drilled in the platform margin.However,up to now,no exploration breakthrough has been achieved.The reason for this is that the reservoir-cap combination conditions are unclear which restricts the success of oil and gas exploration.In this paper,by analyzing the characteristics of seismic reflection structures and seismic stacking patterns,the Cambrian platform margin in Manxi is divided into 3 segments,and a sectional sedimentary evolution analysis is performed.It is pointed out that the differential tectonic subsidence and relative sea level changes are the major factors controlling the differential evolution of the platform margin.Based on the analysis of the differential sedimentary evolution of the platform margin,the differences of the source-reservoir-cap combination conditions in the different segment of the platform margin are discussed.It is pointed out that the Lower Cambrian gentle slope beach covered by occult dolomite in Lunnan area is the most favorable exploration target.The upper Cambrian platform margin reef bank covered by tight limestone in Gucheng area is the second,which is a more favorable prospecting target.This study provides beneficial geological supports for the oil and gas exploration in Manxi area.