Semiotic Modeling and Situation Analysis : An Introduction

Water injection wells are treated to increase their injectivity by first introducing a solvent such as carbon disulfide, carbon tetrachloride or a composition rich in monocyclic aromatics, into the formation surrounding the well. The waxes and/or bituminous materials normally found at or near the surface of such wells are highly soluble in solvents of this kind. In order to assure the stability of the subsequently injected micellar solution, a suitable buffer such as water or a predominantly aliphatic hydrocarbon, e.g., kerosene, gas oil or crude oil, etc., is injected to immediately follow the aromatic hydrocarbon solvent. Thereafter, the micellar solution, usually containing not more than about 50 percent water, is injected and is substantially miscible with the buffer slug. This system of solvent buffer and micellar solution is then forced out into the formation by means of water or other suitable drive agent.