An Acoustic-Based Method for Measuring Surfactant Concentration in FieldApplications

摘要

Numerous enhanced oil recovery(EOR)techniques entail injecting chemical treatments such as surfactantsat a predetermined concentration to achieve targeted results.Typically,these formulations are prepared on-site prior to injection into the reservoir using large mixing tanks.The current quality assurance practicefor proper concentration of treatment materials uses indirect methods such as interfacial tension(IFT)and/or viscosity measurements.These measurements can be lengthy or only suitable for a specific range ofdispersed phase volumes.We examined the prospect of using acoustic measurements as a method to determine surfactantconcentration for quality assessment of chemical injections on-site.The advantage of ultrasound is that itcan characterize both concentrated systems and low dispersed phase volumes.In this study,we acquiredthe sound attenuation of an amphoteric surfactant,Cocamidopropyl Hydroxysultaine(CBS),and in-housepetroleum sulfonate surfactant nano-capsules(NanoSurfactant),within a frequency range of 3-99.5 MHz.We conducted a set of experiments to establish the relationship between acoustic attenuation and surfactantconcentration,and assess the measurements'dependence on variable factors including applied frequency,suspending fluid,and temperature.The data showed a nearly perfect linear fit in the higher frequency range(65-99.5 MHz)where thecoefficient of determination was between 0.979-0.998.Consistent with theoretical predictions,this methodshowed sensitivity to water salinity where the surfactant,at a constant concentration,displayed higherattenuation values in response to the increase in water salinity,allowing the contribution of surfactants tothe acoustic attenuation to be isolated.Our method accurately determined surfactant concentrations usingacoustic attenuation regardless of the surfactant used.Adopting such a robust protocol that can determine surfactant concentration and has the potential toimprove field quality assurance methods would be beneficial for EOR research and industry applicationswhether as a standalone system or in conjunction with other commonly available methods.