Microemulsion Reduces Adsorption and Emulsion Tendencies in Bradford and Speechley Sandstone Formations

Abstract The primary purpose of nonionic surfactants used in well stimulation is to reduce surface tension, contact angle and emulsion tendencies. However, many of these chemicals adsorb rapidly into the surface of the sandstone formation, reducing their effectiveness in reservoir treatments. This study describes the laboratory and field case studies 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 laboratory sand packed column. A laboratory simulated comparison study of an ethoxylated alcohol and microemulsion was used to determine their water recovery properties from gas wells. Field data collected from Bradford and Speechley sandstone formations confirms experimental sand packed column and core flow investigations. Reservoirs treated with microemulsion fluids demonstrate exceptional water recoveries when compared with conventional non-emulsifying surfactant treatments. These investigations and presented field data may be used to optimize chemical treatments. The primary objectives of this study are focused to include: Comparison studies of the microemulsion system with conventional ethoxylated surfactants commonly used in the oilfield to determine their adsorption properties into the proppant pack, surface tension and water recovery.Experimental data comparing effectiveness of conventional surfactants and microemulsion in non-emulsification and regain permeability tests.Present case studies where microemulsion treatments have improved water recoveries in treated gas wells. This paper describes laboratory methods and case histories supporting this investigation. Furthermore, field data collected from several gas wells stimulated in the Bradford and Speechley formations illustrates the microemulsion fluid exhibiting an advantage over the conventional surfactant treatments when water recovery and increased well productivity are of concern to the operator.