Enhancing oil recovery - by successive injections of homogenising, oil-releasing, and protective emulsion slugs and then water

摘要

In a process for enhanced oil recovery, the following series of injections is made into the reservoir from an injection well: (A) a homogenising slug to increase and equalise the resistance to flow; (B) an active slug of increased power to mobilise the oil; (C) if necessary, a guard slug to protect (B) from diln. by water; and (D) water. (A), (B) and (C) are emulsions of oil and water. The viscosity falls along the series (A) to (D). The process is useful where the oil-bearing stratum is inhomogeneous, or where the viscosity of the oil or the concn. of ions of valency 2 or more in the formation water is high. The vol. of oil released per unit vol. injected is high.