盖层类型及其对油气运移聚集的控制作用

COVER TYPES AND THEIR CONTROL OVER HYDROCARBON MIGRATION AND ACCUMULATION

根据盖层封盖机理与岩石孔隙结构的关系，把盖层分为微孔型和微缝型两类。微孔型盖层饱压比值曲线呈单峰态，峰值他压比大于３．０×１０－２ＭＰａ－１，多位于中浅层（源岩生油窗之上），不仅构成油气的直接盖层，而且与流体高能面配合，能形成高效的区域盖层。微缝型盖层由微孔型盖层演化而来，饱压比值曲线具多峰态，峰值他压比小于３．０×１０－２ＭＰａ－１，多位于中深层（源岩生油窗之下），主要起直接盖层作用，作为区域盖层则效率较低。

Based on the relationship between sealing mechanism and rock pore texture, the covering strata can be diyided into micro-pore type and micro-fracture type. The former has monopeak saturation-pressure ratio curve and the peak saturation-pressure ratio is greater than 3. 0×10-2MPa-1; the later has multi-peak curves of saturation-pressure ratio, the peak saturation-pressure ratio is less than 3. 0×10-2MPa-1. The micro-fracture cover beds are the evolution result of micro-pore cover beds, and are mainly buried in mid-deep depth (below oilwindow) ; the micro-pore cover beds are mainly distributed shallower (above oil-window). The micro-pore type could not only be the direct cover bed of hydrocarbon, but also could form high quality regional covering strata in association with high energy fluid surface; the micro-fracture type could only be the direct cover bed.