Environmental concerns and the economic aspects curtail usage of oil-based drilling fluids (OBDF) during the drilling operations through shale formations. The OBDF is highly effective in controlling the swelling potential of the clay-rich shale formations in oil/gas wells. Hydration of shale formation by water-based drilling fluids (WBDF) leads to several problems such as collapse of boreholes, tight holes and stuck pipe which may preclude further drilling and time loss in rectifying the problems, leading to heavy economic losses. Designing the drilling fluid that reduces the interaction with shale, is important for safe and efficient drilling. This study investigates the new gemini surfactants as shale swelling inhibitors in the field of drilling.

To assess the performance of new cationic Gemini surfactants two reliable clay sources were considered. The first clay (Kaolinite) is from an unconventional formation and the second is sodium bentonite. The inhibition characteristics of gemini surfactants were tested using a dynamic swelling tester.

Different formulations based on commercially available solutions for shale swelling inhibitors were applied and compared with cationic shale inhibitor. It was observed that the new gemini surfactants reduced the shale swelling by different percentages for various gemini surfactants based on their spacer length. It also showed acceptable performance compare with common shale inhibitors used in the industry.

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