The natural pressure over the subsurface is the main driving force that leads the oil to ooze out on the surface at extraction. When this pressure works alone at the wellbore, a primary recovery process is experienced.
However, after the well’s lifetime, the reservoir’s natural pressure decays to such level that becomes unable to promote the oil flow to the surface. Hence, additional energy provided by external sources is required to make up for the pressure deficit. At this point, secondary recovery techniques come into play.
Enhanced oil recovery techniques are based on fluid injections into the reservoir, which provides the complement workforce to extract the reservoir’s remaining oil. These techniques, in turn, create a kind of artificial force. Waterflooding, for instance, can be accomplished both on- and off-shore, having seawater, river water or aquifer water as sources.
With secondary recovery, the percentage oil volume is taken up from the reservoir, i.e. the recovery factor may increase considerably depending on the oil and rock characteristics. Several advanced techniques used in the industry these days are generally classified as secondary, tertiary or even quaternary. Examples are steam-flooding, polymer injection, CO2 injection or chemical injection, and a couple of techniques, such as WAG and SAGD.
At LaMEP, this research line includes the following topics:
Thermal recovery (steam-flooding, in situ combustion)
Chemical injection (polymers and WAG)