chemical flooding

1. n. [Enhanced Oil Recovery, Enhanced Oil Recovery]
A general term for injection processes that use special chemical solutions. Micellar, alkaline and soap-like substances are used to reduce surface tension between oil and water in the reservoir, whereas polymers such as polyacrylamide or polysaccharide are employed to improve sweep efficiency. The chemical solutions are pumped through specially distributed injection wells to mobilize oil left behind after primary or secondary recovery. Chemical flooding is a major component of enhanced oil recovery processes and can be subdivided into micellar-polymer flooding and alkaline flooding. The general procedure of a chemical flooding includes a preflush (low-salinity water), a chemical solution (micellar or alkaline), a mobility buffer and, finally, a driving fluid (water), which displaces the chemicals and the resulting oil bank to production wells. The preflush and the mobility buffer are optional fluids.