四川盆地川西坳陷深盆气地质条件分析

一个沉积盆地是否具有深盆气存在可能性，主要从两个方面进行分析，一为是否存在深盆气形成的地质条件，二为是否具有深盆气藏的特征，前者是先决条件，后者是派生条件。

The geological conditions of deep-basin gas in western depression of Sichuan basin

Deep-basin gas accumulation contains huge resources of natural gas, and will be an important target of natural gas exploration. Two aspects decide whether the deep-basin gas can exist. One is the geological conditions for deep-basin gas, the other is the characteristics of deep-basin gas accumulation, and there is a cause-effect relationship between them. The structure and deposition of western Sichuan depression lead to favorable conditions for deep-basin gas: (1) Upper Triassic coal-measure source rock with high gas generating strength and present gas supply provide huge natural gas for deep-basin gas; (2)Good tectonic conditions exist in western Sichuan basin, which has the characteristics of foreland basin and gas generating center overlapping on depression center;(3) The low--porosity and low-permeability sandstone distributing continuously and turning better upward slope is favorable for deep-basin gas formation. Because of an assemblage of the above-mentioned geological features, Upper Triassic gas accumulation has these characteristics such as bearing gas in large area, uncontrolled by structure, gas-water inversion and abnormally high pressure.