Most oil reservoirs produce under the influence of two or more reservoir drive mechanisms, referred to collectively as a combination drive. A common example is an oil reservoir with an initial gas cap and an active water drive ([[:file:drive-mechanisms-and-recovery_fig6.png|Figure 6]]). | Most oil reservoirs produce under the influence of two or more reservoir drive mechanisms, referred to collectively as a combination drive. A common example is an oil reservoir with an initial gas cap and an active water drive ([[:file:drive-mechanisms-and-recovery_fig6.png|Figure 6]]). |