Mechanisms of how surfactants mitigate formation damage due to aqueous phase trapping in tight gas sandstone formations

In this study, therefore, we have investigated the mechanisms of the trapped aqueous phase removal from the tight gas sandstone formations by considering the effect of surfactants on the wettability alteration, the work of adhesion, and the apparent water film thickness.Theoretical analyses suggest that further the larger the contact angle that the drop of water creates with the reservoir rock surface, the less energy is required for producing gas to displace the water from the reservoir. Therefore, the first part of the study was devoted to determining the optimum surfactant type and concentration, which would yield to the maximum water/rock contact angle. Within the experimental conditions of this study, the maximum increase in the contact angle was obtained when 0.05 wt% cationic surfactant solution was used.Results from further experimental work have shown that the 0.05 wt% cationic surfactant solution was conducive to reduce the work of adhesion, the water saturation and the apparent water film thickness, thereby, effective to remove the aqueous phase trapping damage and regain the rock permeability. Results have also demonstrated that surfactants become more effective in removing the trapped aqueous phase as the drawdown pressure increases.Graphical abstract
Source: Colloids and Surfaces A: Physicochemical and Engineering Aspects - Category: Chemistry Source Type: research
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