Development of Novel Shale Swelling Inhibitors Using Hydrophobic Ionic Liquids and Gemini Surfactants for Water-Based Drilling Fluids

In the last decade, hydrophilic Ionic liquids have been emerged as an additive in drilling fluids for clay swelling inhibition. However, the application of hydrophobic Ionic liquids as a clay swelling inhibitor have not been investigated. In this study, the combination of hydrophobic Ionic liquids and Gemini surfactant were studied to evaluate the inhibition performance. The novel combination of hydrophobic ionic liquid (Trihexyltetradecyl phosphonium bis(2,4,4-trimethyl pentyl) phosphinate) and cationic gemini surfactant (GB) was prepared by mixing various concentrations of both chemicals and then preparing water based drilling fluid using other drilling fluid additives such as rheological modifier, filtration control agent, and pH control agent. The wettability of sodium bentonite was determined by contact angle with different concentrations of combined solution. Some other experiments such as linear swelling, capillary suction test (CST) and bentonite swell index were performed to study the inhibition performance of ionic liquid. Different concentrations of novel combined ionic liquid and gemini surfactant were used to prepare the drilling fluids ranging from (0.1 to 0.5 wt.%), and their performances were compared with the base drilling fluid. The wettability results showed that novel drilling fluid having 0.1% Tpb-P - 0.5% GB wt.% concentration has a maximum contact angle indicating the highly hydrophobic surface. The linear swelling was evaluated over the time of 24 hours, and least swelling of bentonite was noticed with 0.1% Tpb-P - 0.5% GB wt.% combined solution compared to linear swelling in deionized water. Furthermore, the results of CST also suggested the improved performance of novel solution at 0.1% Tpb-P - 0.1% GB concentration. The novel combination The novel combination of hydrophobic ionic liquids and gemini surfactant has been used to formulate the drilling fluid for high temperature applications to modify the wettability and hydration properties of clay. The use of novel combined ionic liquid and gemini surfactant improves the borehole stability by adjusting the clay surface and resulted in upgraded wellbore stability.