塔里木盆地轮南奥陶系古潜山油气成藏与分布

RESERVOIR CHARACTERISTICS AND DISTRIBUTIONS OF THE ORDOVICIAN BURIED HILL RESERVOIR IN LUNAN, TARIM BASIN

轮南奥陶系碳酸盐岩古潜山形成于晚加里东 海西期 ,经过多期构造运动的改造 ,形成了现今的构造格局 ;经过了多期成藏过程 ,形成了现今复杂的油气水分布特征。轮南奥陶系古潜山油气主要分布在潜山围斜部位 ,潜山面以下约 1 5 0m范围内 ,原油分布不受局部构造影响。总体看来 ,轮南奥陶系古潜山油气分布主要与储集空间的分布、水动力作用和差异聚集作用有关 ;轮南奥陶系古潜山油水界面是倾斜的 ,油气藏具有一定的水动力特征 ,可能是一个大型的水动力圈闭油气藏。

The Lunnan Lower Uplift was a sub-order unit of the North Tarim Rise and a multiple oil-gas accumulation play, with the Ordovician buried hill reservoir being an important kind of accumulation play. The Ordovician buried hill created in the period of Later Caledonian to Hercynian orogenies, and got its tectonic framework in the Indosinian movement. Since it experienced multiple reformation by tectonic events and multiple accumulation in Meso-Cenozoic, the oil, gas and water had a complicated distribution. The main characteristics of accumulation and oil-water interface, and formation and evolution of accumulation were discussed then a model for oil-gas reservoir in Lunnan area presented in the paper. The Ordovician buried hill accumulation was preserved within 150 metres under the face of the buried hill,surrounding the hill slopes, where the distribution of crude oil was few influenced by the local structures. Generally speaking,the oil-gas distribution in the Lunnan Ordovician buried hill was chiefly controlled by reservoir space,hydrodynamics and differential entrapment. The oil-water interface in the Lunnan Ordovician buried hill was tilted,and the related reservoir might be a super hydrodynamic trap one, so the oil-gas accumulation had a unique hydrodynamic features.