(183i) Designing Conformance Control Foams for a Field Test with CO2 Soluble and Brine Soluble Surfactants

One of the ways of improving mobility control during CO2 Enhanced Oil Recovery (EOR) is the generation of CO2-in-brine foams.  In this study we outline the lab-scale experimental results used in the planning of a single well injector field test in which the foaming surfactant is dissolved in the brine.  The objective of this test is to form a foam in a high permeability layer that contains little oil into which the majority of injected CO2 enters; this conformance control foam is intended to block the thief zone and promote the flow of CO2 into the lower permeability, oil-bearing zones.   This lab-scale investigation includes studies of surfactant solubility in high salinity brine; the design of the appropriate surfactant-salt-water solution for injection; the ability to mix the injected surfactant solution with higher salinity in-situ brine without the surfactant coming out of solution (i.e. avoiding “precipitation losses”); the ability of surfactant solution to generate a stable high quality CO2-in-brine foam in an agitated windowed vessel; the measurement of the dramatic, transient increase in pressure drop (due to foam formation) across a sandstone or carbonate core initially saturated with the surfactant solution when CO2 is introduced; the steady state pressure drop across a core when surfactant solution and CO2 are simultaneously injected;  the adsorption of surfactant onto crushed porous media in static tests; the adsorption of surfactant from solution flowing through a consolidated core; and CT imaging of CO2 entering a core initially saturated with surfactant solution.  The first field test will involve introducing the surfactant only in the brine and alternating its injection with CO2 gas (SAG).  Plans for another field test in which one surfactant is added to the brine and a nonionic surfactant is added to the CO2 will also be discussed (SAGS).