库车坳陷西秋构造带盐下低幅度构造圈闭研究及勘探思路

Study and Exploration Idea about Low-amplitude Subsalt Structure Traps in Xiqiu Structural Belt,Kuqa Depression

库车坳陷西秋构造带资料解释存在"浅T8"解释方案和"深T8"解释方案的争论,地震层位的不同地质层位确定,造成盐下构造的解释方案、圈闭性质及大小、高点埋藏深度存在很大差异,导致西秋构造油气勘探思路和部署引向截然不同的方向。综合地震、地质和测井资料分析,西秋构造带古近系盐层内部的稳定地震反射层是盐层内部膏泥岩的反射,而不是白垩系砂泥岩的反射。因此,西秋构造带不存在大型盐下构造圈闭的可能,应该立足于"西秋构造带的盐下构造为北倾单斜带上的低幅度构造圈闭"认识,进行西秋构造带盐下圈闭油气勘探的整体部署。

There is a dispute between two options---'Shallow T8'and Deep T8'for data interpretation of Xiqiu structural belt,Kuqa Depression.Determination of different geological horizons of seismic horizons resulted in the huge difference in interpretation options,trap property and size,and burial depth of highs of subsalt structure.So the oil and gas exploration idea and deployment of Xiqiu structural belt were altered completely.Synthesizing seismic,geological and logging data showed that seismic reflection layers were not the reflection of Cretaceous sandstone and mudstone,but the gypsum mudstone inside the Palaeogene salt bed of Xiqiu structural belt.Therefore,no large subsalt structural traps were likely to exist in the structural belt.Overall deployment should be carried out for oil and gas exploration in subsalt traps,based on the recognition that 'the subsalt structure of Xiqiu structural belt is low-amplitude structural trap at the monoclinic belts tilting to the north'