Secondary Recovery
Injecting water or gas into a reservoir to repressure it and push additional oil to the wellbore after primary production has depleted natural pressure.
Secondary recovery is a second stage of production that adds energy back to a reservoir after the original pressure has been drained. The most common method is a waterflood — injecting water through dedicated wells to sweep oil toward the producing wells — though gas injection is also used. It comes after primary recovery, which relies on the reservoir's own pressure plus artificial lift.
Primary recovery alone often leaves the majority of the oil in the ground; secondary methods can recover a meaningful additional share. Setting up a waterflood is a significant working-interest investment, frequently done through a unitized field where many tracts are operated together as one.
For a mineral owner, secondary recovery can extend a field's life and your royalty by years — but it usually involves unitization and a new division of interest, so it is worth understanding how your share is being recalculated.