Abstract: The sealing ability of the cap rock is an important iactor in the formation and conservation of natural gas in a gas reservoir.Based on the results of study of lithology,thickness,and depth of burial of the cap rocks on Tertiary gas reservoirs,this paper gives a further study of the breakthrough pressure,median radius,concentrated pore size and its percentage,the amount of pores with a radius of less than 630,type of micropores distribution of the cap rock,3 grades of cap rocks are classified for their quantitative evaluation.The mechanism of the formation of a natural gas reservoir is demonstrated to give a basis for the understanding of the distribution of gas reservoir to promote future gas exploration.

摘要： 天然气盖层封闭性能的好坏是天然气能否形成气藏并得以保存的重要条件,本文在对第三系天然气盖层的岩性、厚度、埋藏深度等定性评价的基础上,利用压汞——吸附合并计算法求得了盖层的突破压力、孔隙中值半径、孔隙半径集中范围和含量、微孔隙半径小于630的含量、微孔隙半径分布类型、气柱高度和遮盖系数等.提出了盖层评价的6项指标和三级分级标准,并以此对济阳坳陷第三系天然气藏盖层进行了定最评价.在此基础上,闸述了本区天然气藏的成藏机理,为认识天然气藏分布规律提供了依据.

关键词: 济阳坳陷, 天然气藏, 突破压力, 泥岩盖层, 孔隙半径, 盖层评价, 浅层天然气, 天然气盖层, 形成机理, 分布类型