碎屑岩天然气储集层次生孔隙的三种成因机理

Three formation mechanisms of secondary porosity in clastic gas reservoir rocks.

我国碎屑岩天然气储集层分布广泛，其储集性能多属低孔低渗、特低孔特低渗，储集物性差； 孔隙类型以次生孔隙为主。从实例出发， 论述其次生孔隙的三种形成机制：有机酸及二氧化碳酸性水的溶解，这种机制形成的次生孔隙主要分布在煤系天然气储集层中；深部地层热循环对流形成局部次生孔隙， 主要见于我国东部深层碎屑岩中；古风化壳的表生淋滤和断裂带附近的淋滤作用形成次生孔隙。研究结果为天然气储集层有利孔隙段及有利孔隙带的预测打下了基础。图１ 参３（ 邹冬平摘）

Clastic gas reservoir beds are widely spread in our country, most of them are characterized by low porosity, low permeability or ultra low porosity and ultra low permeability, inferior reservoir properties; and secondary porosity is the main porosity type. 3 formation mechanisms of secondary porosity are discussed in this paper: ①The dissolution of organic acids and CO 2 acidic water. The secondary porosity formed by this mechanism distributes mainly in coaliferous gas reservoir beds; ②Local secondary porosity formed by a cyclic convection of heat in deep strata; this secondary porosity appear mainly in deep clastic rocks in the eastern part of China and ③Secondary porosity formed by leaching in surface leaching and faulting belts are near to a weathered paleocrust. Result of study gives a basis for prediction of favorable porous zones and favorable porous belts in gas reservoir beds.