SURFACTANT-BASED MOBILITY CONTROL

Smith, D.H. Surfactant-Based Mobility Control - Progress in... 

Surfactant-Based Mobility Control Progress in Miscible-Rood Enhanced Oil Recovery Smith, Duane H., Ed. ACS Symposium Series No. 373 American Chemical Society Washington, D.C., 1988. 

As the first book on the subject, this volume summarizes the current status of surfactant-based mobility control and a goodly fraction of the research that has been performed on this emergent technology. 

Steps in the Development of Surfactant-Based Mobility Control. Although surfactant-based sweep and mobility control for gas flooding are still in the research stage, major advances have been made in several areas from which a pattern of past and probable future development can be inferred. In approximate historical order, the steps in this development include the following ... 

Mast, in a pioneering 1972 paper, reported visual observations of foam flow in etched glass micromodels (37 ) His observations showed that some of the conflicting claims about the properties of foam flow in porous media were probably due simply to the dominance of different mechanisms under the various conditions employed by the separate researchers (37). Mast observed most of the various mechanisms of dispersion formation, flow, and breakdown that are now believed to control the sweep control properties of surfactant-based mobility control (37,39-41). 

A key factor in the commercialization of surfactant-based mobility control will be the ability to create and control dispersions at distances far from the injection well (TJ ). Capillary snap-off is often considered to be the most important mechanism for dispersion formation, because it is the only mechanism that can form dispersions directly when none are present (39,40). The only alternative to snap-off is either leave-behind, or else injection of a dispersion, followed by adequate rates of thread breakup and division to maintain the injected lamellae. 

While mechanistic simulators, based on the population balance and other methods, are being developed, it is appropriate to test the abilities of conventional simulators to match data from laboratory mobility control experiments. The chapter by Claridge, Lescure, and Wang describes mobility control experiments (which use atmospheric pressure emulsions scaled to match miscible-C02 field conditions) and attempts to match the data with a widely used field simulator that does not contain specific mechanisms for surfactant-based mobility control. Chapter 21, by French, also describes experiments on emulsion flow, including experiments at elevated temperatures. 

In surfactant-based mobility control, surfactant adsorption is important in at least four ways ... 

Phase Behavior and Surfactant Design. As described above, dispersion-based mobility control requires capillary snap-off to form the "correct" type of dispersion dispersion type depends on which fluid wets the porous medium and surfactant adsorption can change wettability. This section outlines some of the reasons why this chain of dependencies leads, in turn, to the need for detailed phase studies. The importance of phase diagrams for the development of surfactant-based mobility control is suggested by the complex phase behavior of systems that have been studied for high-capillary number EOR (78-82), and this importance is confirmed by high-pressure studies reported elsewhere in this book (Chapters 4 and 5). 

These two branches, simulator development and materials selection, can then come together in well-engineered designs for field use of surfactant-based mobility control in gas flooding. 

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