深盆气藏地质特征与研究意义——以鄂尔多斯盆地为例

Geological Characteristics of Deep Basin Gas Traps and Their Research Significance Erdos basin Example

深盆气藏位于构造下倾部位或盆地中央 ,上部含水 ,是具有特殊成藏地质条件的非常规气藏。深盆气藏具以下特征 :气在下水在上的气水倒置 ,气藏流体压力低于静水压力 ,烃源岩与气藏紧密伴生 ,源岩生气量大供气充足 ,油气热演化程度高 ,储层具低孔隙度低渗透率 ,单井产量低但地质储量大等。本文以我国鄂尔多斯盆地为例进一步阐明深盆气藏的特征。国外对深盆气藏研究极为重视 ,天然气的产量也占有很大比重。在我国研究程度较低 。

Deep basin gas traps are referred to those abnormal gas traps formed under special geological conditions and located in the downward inclined part of a structure or in the central part of a basin, with water in their upper parts. The deep basin gas traps are characterized by: the gas/water upside-down pattern i.e., gas in the lower part while water in the upper part; the pressure of gas trap fluids lower than the hydrostatic pressure; hydrocarbon source rocks in close association with gas traps; source rocks producing large amounts of gases; higher degree of oil and gas thermal evolution; low porosity and low permeability of the reservoir strata; and low single-well yield but large geological reserves. A case study has been conducted in the present paper with the Erdos Basin in Northwest China as an example. Great attention has been paid to the study of deep basin gas traps abroad because the production of natural gases accounts for a considerable proportion of the total yields throughout the world. In China there is still a big gap in research in this aspect. It is of great significance to carry out detailed investigations into deep basin gas traps in exploration and development of China's natural gases