Insight into selection of appropriate formulation for colloidal gas aphron(CGA)-based drilling fluids

Application of light-weight drilling fluids is essential to develop depleted hydrocarbon reservoirs.Recently,colloidal gas aphron(CGA)-based fluids have been introduced for such applications due to their ability in controlling fluid losses.In this work,a comprehensive experimental study was performed to choose the best formulation for CGA fluids by implementing static stability tests,rheological behavior measurements,and bubble size analyses of CGAs.Xanthan gum polymer and sodium dodecyl benzene sulfonate(SDBS),an anionic surfactant,and cetyl trimethyl ammonium bromide(CTAB),a cationic surfactant,were utilized to prepare CGAs.For the range of experiments conducted,the performance of CGA fluids prepared with SDBS was improved by increasing the polymer and surfactant concentrations.However,for CTAB,it was improved by an increase in the polymer concentration and a decrease in the surfactant concentration.The formation of white,long hair-like precipitates observed at high levels of CTAB caused CGA fluid to become rapidly unstable.Also,it was observed that the size of CGAs was significantly influenced by the polymer and surfactant concentrations.The most stable bubbles were formed at 6.86 g/L of polymer concentration.The results of this study provide insights into appropriate formulation for CGA-based fluids which could be potentially applicable in drilling operations.

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.