TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe primary purpose of surfactants used in stimulating sandstone reservoirs is to reduce surface tension of the fracturing fluid, decrease interfacial tension between injected fluid and reservoir rock and increase post-fracturing fluid recovery. However, many of these chemicals when injected at high pressures adsorb rapidly into the sandstone formation, reducing their effectiveness in post fracturing fluid recovery.This study describes simulated laboratory experiments and case histories of various surfactants used in the oilfield. Several different surfactants including ethoxylated linear alcohol, nonyl phenol ethoxylate and a microemulsion system were investigated to determine their adsorption properties when injected into a sand packed column. A laboratory simulated comparison study of these surfactants versus a microemulsion system was used to identify their water recovery properties from gas wells.Field data collected from Benson, Balltown, Injun, and Speechley Sandstone formations confirm experimental sand packed column and core flow investigations. Reservoirs treated with microemulsion fluids demonstrate exceptional water recoveries when compared with conventional nonemulsifying surfactant treatments. Case histories reported from several gas wells stimulated in the Appalachian Basin illustrate the advantages microemulsions have over conventional surfactant treatments when faster cleanup, increased post fracturing fluid recovery and well productivity are of concern to the operator.