川西坳陷深盆气研究进展与问题讨论

Advances and discussion about the study on deep basin gas in western Sichuan province depression

川西坳陷总体上看具有与加拿大阿尔伯达盆地类似的地质条件,极可能发育深盆气藏。详细研究表明,两盆地在构造回返程度、地层压力特征、气源岩生气时代等方面存在较大差异,不宜将川西坳陷的天然气聚集简单地归结为阿尔伯达型深盆气藏。研究其成因和分布规律,应从该盆地的实际资料入手,进行成藏机理研究,而不能简单地借用已有的模式进行对比。研究认为,川西坳陷的天然气藏具有"气水倒置"的特征;川西坳陷的断裂体系深刻地影响着深盆气聚集成藏,导致盆地天然气的独特分布形式。对深盆气成藏诸控制因素,包括源岩厚度、有机质成熟度、生气强度、储集层厚度与物性、断裂构造特征等的综合研究,对川西坳陷深盆气藏的分布进行了预测。

Western Sichuan province depression has geological conditions similar to Alberta basin of Canada in which deep basin gas most probably was formed . However, detailed study showed that the intensity of structural reversion, pressure attributes of gas-bearing strata, and the time of gas generation of source rocks of these two basins are quite different. So it is not reasonable torta basin. For the purpose of studying the accumulation mechanism and distribution discipline of gas reservoirs of western Sichuan province depression, it will be better to start with practical geological conditions of that depression, rather than to simply compare it with an available model. It is thought that the gas pools in western Sichuan province depression have the feature of reversed gas-water contact. As only a few data of formation pressure are available, this point of view needs further study. It is considered that the fault system in western Sichuan province depression has a strong influences on the accumulation of deep basin gas pools, and has led to a peculiar distribution pattern of deep basin gas in that basin.It terms of comprehensive study of the controlling factors including burial depth of source rocks, organic matter maturity, gas generation intensity, reservoir property, structural pattern, etc., a rough prospecting of deep basin gas distribution of western Sichuan province depression was made.