东濮凹陷文23气藏成藏条件分析

Reservoir-forming Conditions of Wen23 Gas Reservoir in Dongpu Depression

文 2 3气藏是东濮凹陷典型的煤成气块状砂岩气藏 ,气源为石炭二叠系 ( C-P)煤系地层。气源岩有机质丰度高、性质好 ,天然气与气源岩地化指标具有很好的可对比性。该气藏储层发育 ,单层厚度大 ,分布稳定 ,连通性好 ,储层岩性为粉砂岩、细粉砂岩 ,属中低孔低渗致密储层。气藏圈闭条件好 ,为在基岩隆起背景上长期发育形成的背斜构造。气藏之上覆盖有巨厚的盐岩盖层 (文 2 3盐 ) ,使得文 2

Wen23 Gas pool is a typical massive sandstone gas reservoir of coal formed gas in Dongpu depression, in which gas source beds are coal measures of Permo Carboniferous(C P) and the source rocks have good characteristics and high abundance of organic matter The geochemical indicators of natural gas and source rocks have good comparabilities The gas reservoir rocks are typical of big thickness in single layer, steady distribution and good continous, and are composed of siltstone and fine siltstone, having middle low porosity and low permeability or heavy compactness The reservoir traps are good anticline structures, resulted from the basement uplift for a long time The top of gas reservoir is covered by a salt formation of very big thickness(called salt Wen 23) , which makes Wen23 gas reservoir well protected