Super gas wet and gas wet rock surface: State of the art evaluation through contact angle analysis

Recently, super gas wet and gas wet surfaces have been extensively attended in petroleum industry, as supported by the increasing number of publications in the last decade related to wettability alteration in gas condensate reservoirs. In many cases, contact angle measurement has been employed to assess the wettability alteration. Even though contact angle measurement seems to be a straightforward approach, there exist many misuses of this technique and consequently misinterpretation of the corresponding results. In this regard, a critical inspection of the most recent updated concepts and the intervening parameters in the contact angle based wettability evaluation of liquid-solid-gas systems could aid to provide some remediation to alleviate this problem. To this end, this work presents a survey on the accurate terms and rigorous protocols based on the community of surface science and chemistry. As a preliminary step, advancing, receding, static, and the most stable contact angle terminology are defined. The study is followed by the definition of the contact angle hysteresis effect. The application of surface free energy in the selection of the best gas wet agent is then analyzed. Afterward, the impact of the size-dependent behavior of drop on contact angle is discussed. Finally, a sessile drop experiment is explained to achieve the defined parameters. For future contributions to petroleum industry journals, like this journal, this work could offer an easy use of the conceptual framework for analyzing the results and comparative evaluations in chemical wettability modifier agents.