塔里木盆地库车坳陷第三系盐构造与油气

塔里木盆地北部的库车坳陷第三纪发育盐湖,沉积了巨厚的膏盐岩层,在喜山运动中晚期强烈的构造挤压下形成了大量的盐构造,造成深浅层构造不一致,库车盐构造的类型有丘形、喇叭形、劈形、拱形、脊形,广泛分布于库喀断褶带、拜城向斜带、秋立塔克断褶带及羊塔克-亚肯背斜带,其演化按构造位置可分为两种情况。盐岩不仅是极好的区域性盖层,还可改善盐下岩层的储集物性,而三叠-侏罗系烃源岩又位于盐下,因此盐下构造圈闭是库车坳陷最为有利的勘探远景目标。在世界含油气盆地中,笔者发现伊朗油田与库车坳陷具有相似的构造特征和油气聚集规律,挤压型盐构造非常发育。盐岩及盐构造对于库车坳陷形成大中型油气田起着非常重要的作用,应加强对盐下构造圈闭的勘探。

TERTIARY SALT STRUCTURES AND HYDROCARBONS IN KUCHE DEPRESSION OF TARIM BASIN

Over one thousand meter-thick evaporate rocks that are highly plastic were deposited in the Tertiary salt lake in Kuche depression of Tarim Basin.During the middle-late stage of Himalayanorogeny, a large number of salt structures were formed and disharmonized the above structures from the below.The types of salt structure were identified, including salt dome, salt arch, salt flare, salt ax and salt ridge.Salt structure is widely developed in the Kuka fault-folded belt, Baicheng synclinal belt, Qiulitake fault-folded.belt, Yangtake-Yaken anticlinal belt.The salt structures were evolved through two different ways according to their position.Salt rock is an exceedingly good regional cap formation to preserve hydrocarbons.Moreover, salt rock has a series of excellent characteristics that can improve the property of subsalt reservoirs.Triassic-Jurassic hydrocarbon source rocks that lie below the salt layer can directly provide oil and gas to subsalt structure traps.Thus it can be seen that subsalt structure traps are favorable exploration targets.Compared with other petroliferous basins in the world, the authors find the oil fields in Iran have similar structure features and the ways of oil accumulation with the Kuche depression.It is suggested that efforts should be done to look for subsalt traps.