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我国碎屑岩天然气储层以次生孔隙为主,其形成机理大致可归纳为以下三种:(1)有机酸及二氧化碳酸性的溶解,主要分布在以煤系地层为气源岩的储集层中,如鄂尔多斯盆地中部气田、文留气田、苏桥气田、吐哈盆地、崖13气田等;(2)表生淋滤及断裂淋滤,在不整合面上的表生作用或断裂带附近的淋滤作用形成风化壳次生孔隙;(3)深部热循环对流。中国东部深层(3500m 或4000m 以下)碎屑岩中的热循环对流是其次生孔隙形成的主要原因。次生孔隙的分布与成岩流体的流动方式有关,常见的流动方式有下降流、上升流和热循环对流。下降
The formation of clastic natural gas reservoirs in our country is dominated by secondary pores. The formation mechanism of clastic natural gas reservoirs in China can be summarized as follows: (1) Dissolution of organic acids and carbon dioxide is mainly distributed in coal-bearing formations as source rocks Layer, such as gas field in Ordos Basin, Wenlv gas field, Suqiao gas field, Turpan-Hami basin and Yag13 gas field; (2) superficial leaching and fracture leaching, The formation of weathering shell secondary porosity by leaching nearby; (3) Deep thermal convection. Heat convection in the deep (3500m or below) clastic rocks in eastern China is the main reason for the formation of secondary pores. The distribution of secondary pores is related to the flow pattern of diagenetic fluids. The common flow patterns include descending flow, ascending flow and thermal cycling convection. decline