On the True Origin of "Continuous Injection" High Pressure Gas Flood, Continuous Injection Surfactant Flood and Foam Flood in EOR : Some Comments and Critiques
Authors: Das Ashis Kumar 
Published: December 2007

The need for continuous injection rather than slug (small amount) injection has not been stated by many expert EOR (enhanced oil recovery) scientists over the life of EOR till date explicitly yet the technology seems to be getting into commercial applications in the US especially and many other parts of the world such as China, India and USSR, without actual mention of the true origin of the several areas where this concept has been commercially applied. In this paper I propose a presentation that establishes the true origin of the several areas where this concept has been applied born from an experimental work by the author while pursuing a graduate degree work on investigation of additional roles of polyacrylamide polymer beyond commonly known mobility control.

Since the start of water flood accidentally more than a century ago, and its perusal in application and research in form of improved water flood with mobility control polymers, and surfactants and other chemicals (alkali etc) and the likes, the EOR based on aqueous methods has gone far ahead especially in the oil embargo period. The major mentions are the works of Taber, Mungan, Gogarty , Pope, Lake, Schecter, Menzie etc. However, all these works involved critical thinking against use of the chemicals in large amounts with fear of loss of chemicals in unknown crevices and lost zones in the oil pools and adjacent areas of cavernous types. But these exponents of EOR apparently failed to understand that : (1) in a thoroughly (or even moderately) water flooded pool, traced well about informations relating to water laid zones and adjacent residual oil areas from tracer and pressure surveys , there is no fear of losing costly chemicals, and (2) more chemicals are required for global (poolwide) removal or mobilization of residual oil, and (3) additional pressure drop may be applied across the residual oil for mobilization by application of continuous injection rather than slug injection.

In this paper, I outline step by step, showing how three special applications namely continuous injection surfactant flood, continuous injection high pressure gas flood and continuous injection foam flood have developed over the years from our primal experiment (1981–1983) in which I first unfolded the benefits of continuous injection in form of the most important item among above three viz. the third item which is availability of additional pressure drop across the residual oil yet no reference was made in the literature about our first work. Also despite some applications of the above three methods, fear still seems to prevail about continuous injection on similar bases which prevailed earlier and I address the issue to eradicate this fear from EOR application peoples’ minds with arguments and critiques.

A moderate part of the paper deals with the special role of diffusion of residual oil particles into outer aqueous layer/zone due to density increase during flow thru porous medium of non-Newtonian fluids at elevated pressure and temperature, and related new kind of revealations of importance to flow thru porous media subject in general.