Development of Surfactants for Chemical Flooding at Difficult Reservoir Conditions

Abstract

Abstract The production and properties of two families of anionic surfactants (internal olefin sulfonates and branched C16, 17 alcohol-based alkoxy sulfonates) are described for chemical flooding of oil reservoirs at high temperatures and/or high salinities. Surfactant properties measured include oil/water micro-emulsion phase behaviour obtained using new glassware-based procedures appropriate for higher reservoir temperatures. The results obtained relate to oil/water interfacial tension behaviour and give the"operating window" of the surfactants in terms of their optimal salinity and ability to solubilise oil in the micro-emulsion. The phase tests also give information on the quality of the micro-emulsions obtained where low viscosity and absence of gels is desirable. The surfactants described are promising for EOR and can be produced in commercial quantities. Different IOS products are available with different carbon chain cuts (with range C15 to C28) allowing matching of the IOS to the temperature, salinity and crude oil type of reservoirs. In addition, both IO carbon chain (degree of branching) and the degree of sulfonation influence the surfactant properties of the IOS mixture formed which provides a means for tailoring an IOS surfactant for optimal performance.