含油气盆地水文地球化学规律

HYDROGEOCHEMICAL REGULARITY OF PETROLIFEROUS BASINS

从自流水盆地整体出发,研究了盆地油气成藏的水文地球化学演变规律,得出以下新认识:1)盆地内地下水的水平运动,使水化学成分从供水区到排泄区呈现有序变化,为研究油气水之间的关系、揭示油气成藏的分布规律提供了水文地质依据;2)自流水盆地内存在2种截然不同的水文地质系统,其变化受控于盆地的次一级构造单元;3)自流水盆地内渗入成因水和沉积成因水的径流特征、驱动能量、水化学成分具有很大差异,对油气的生、运、聚、散会产生不同的影响,二者形成的锋面是不同性质油气聚集的地理分界线;4)与油气有关的浅层水文地球化学效应可分布在自流水盆地的不同水文地质单元内,尤其是控油断裂带与生油中心区上方。总体上看,含油气盆地地下水化学异常的变化特点与分布规律均与油气藏存在密切关系,因此可用于评价盆地含油气远景,预测油气赋存有利区。

The hydrogeochemical evolution regularity of oil and gas accumulation in an artesian basin has been studied by taking the artesian basin as a whole. Some new understandings are gained as follows： 1） The horizontal movement of the underground water within the basin causes the hydrogeochemical compositions to change regularly from the water recharge area to the water discharge area, providing the hydrogeological basis for studying both the relationship among oil, gas and water, and the distribution regularity of oil and gas accumulations. 2） Two distinct hydrogeological systems exist in the artesian basin, which are controlled by the sub-structures of the basin. 3） The runoff characteristics, the drive energy and the geochemical compositions of the penetration water and the sedimentary water within the artesian basin may differ obviously, and may exert different effects on the generation, the migration, the accumulation and the dispersion of oil and gas. And the front interface of the two kinds of water can act as the geographical border of the oil accumulations with different properties. 4） The shallow hydrogeochemical effects related to oil and gas may distribute in various hydrogeological units of the artesian basin, especially in the oil-controlling fault zones and the oil-generative centers. In a whole the characteristics and the distribution regularity of the hydrogeochemical anomaly are closely related to oil and gas, and can be used to evaluate the oil and gas prospects, as well as to predict the favorable zones for oil and gas to accumulate.