OIL RECOVERY BY WATERFLOODING WITH IMPROVED MOBILITY CONTROL

摘要

Waterflooding employing the use of an initial mobility control slug which is graded at its front end by progressively increasing its viscosity and a terminal mobility control slug which is graded at its back end by progressively decreasing its viscosity. An intermediate mobility control slug of substantially constant viscosity may be injected between the initial and terminal slugs. The invention may be carried out in conjunction with surfactant or alkaline waterflooding.