Guaranteeing the civil engineering structures’ safety around oil wells is a crucial problem in civil and environmental engineering. The spillage of crude oil (CO) in soils leads to an intense decline in strength, causing severe ecosystem catastrophes. This matter is critical for oil-rich nations, such as Iran, with numerous CO resources. This study performs precise chemical analysis and cyclic and static simple shear tests (SSTs) on Bushehr carbonate sand (BCS). Since the dynamic resistance of carbonate sand (CS) is significantly different from quartz sand, this study investigates the CO-contaminated BCS. This investigation introduced a novel method for CO adsorption from contaminated carbonate sand. Bentonite nanofluid (BNF) is a novel soil treatment agent that considerably enhances the CO-contaminated BCS strength. The relative density of BCS specimens for SST was 60%, and CO in contaminated BCS samples was 6wt% (designated contamination level). This purpose was to explore the influence of CO contamination and the efficiency of an environmentally friendly stabilizer known as BNF, aiming to encounter polluted areas. Four different natural bentonites were studied to obtain the optimum type for preparing BNF. This paper uses SST (in static and cyclic states), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope, and X-ray diffraction analysis. The optimal CO-adsorption was 6wt% of BNF. Using BNF (as a novel treatment agent presented in this paper) causes approximately 20% and 17% increases in dynamic and static strengths of CO-contaminated BCS. The FTIR analysis confirmed the physical experiments and indicated that the peak of the C–H bond is remarkably declining due to the high efficiency of this novel technique in crude oil adsorption.
