Nonionic and anionic surfactants as flowback aids in hydraulic fracturing methods of crude oil production

Surfactants find utility in hydraulic fracturing operations for their ability to modify rock wettability and increase the flowback of fracturing fluid following proppant delivery. The performance of a series of nonionic and anionic surfactants was evaluated by gravity drainage displacement testing. Alkylbenzenesulfonates having alkyl chains possessing at least 16 carbons were among the best performers, yet a similar surfactant having an alkyl chain possessing only similar to 12 carbons performed quite poorly. These data illustrate that a critical chain length exists for this series. Lauryldimethylamine oxide also performed well. In general, those surfactants possessing the greatest ionic character outperformed nonionic surfactants. Critical micelle concentration, surface tension, contact angle, relative solubility number, and hydrophilic-lipophilic balance were determined for each surfactant studied. Unexpectedly however, few correlations between any of these physical and surface properties and performance in gravity drainage displacement tests were identified, underscoring the complexity of selecting surfactants suitable in the application. These data suggest that more real-world test methods, employing stationary phases, temperatures and pressures that better mimic the fields and individual wells being considered, are needed to better guide surfactant selection.