加拿大西部原油多生于垂直连续的礁相碳酸盐岩沉积地层，其开采方法为气驱，且采收率很高。当油层衰竭只留下一个夹层时，油藏便进入压降阶段，即在构造与顶部之间产生气顶。此时若存在一下伏含水层，则含油夹层就会被向上驱替而进入先前的气驱油层，若不存在则可用底水注入来确保对整个气驱油层的驱替。逐次驱替法由此而得名，并且通过实领室实验和现场实际观察结果得到进一步的证实。 More crude oil in western Canada is born in vertically continuous reef carbonate deposits, which are gas-flooded and have high recovery rates. When the reservoir depletes leaving only one mezzanine, the reservoir goes into a pressure drop phase, producing a gas cap between the formation and the top. At this point, if there is a subsurface aquifer, the oil-bearing interlayer will be displaced upward to enter the previous gas-flooding reservoir. If not, bottom-water injection may be used to ensure displacement of the entire gas-bearing reservoir. Successive flood method thus named, and through real laboratory experiments and field observations to obtain further confirmed.