Evaluation the effect of wheat nano-biopolymers on the rheological and filtration properties of the drilling fluid: Towards sustainable drilling process

Drilling fluid plays a crucial role in the drilling operation of the oil and gas wells by serving various functions including controlling formation pressures, preserving borehole stability, and removing drill cuttings. However, the loss of the drilling fluid into formations can lead to the permeability damage, groundwater contamination, and altered formation integrity. In addition, the waste generated from drilling activities poses environmental issues, particularly when drilling fluids containing substances, such as heavy metals are discarded. Water-based drilling fluids (WBDFs) are preferred due to their eco-friendliness and cost-effectiveness. However, they suffer from inadequate rheological and filtration properties, prompting the introduction of additives. This study evaluates the use of wheat grain as nano-biodegradable additives in WBDFs, focusing on different sizes of wheat powder ranging from nano to course particle size. Nano-biopolymers (WNBPs) were prepared from breaking down into the nanosized structure using the ball mailing approach and characterized using XRF, FTIR, TGA, DLS, SEM and TEM. Several drilling fluids including the reference, modified, biodegradable and nano-biodegradable drilling fluids were prepared from API SPEC 13A standard, carboxymethyl starch (CMS), wheat powder (WP) at 75–600 µm and nano-biopolymer (WNBPs), respectively. The formulated drilling fluids were investigated by conducting different measurements, such as pH, rheology, filtration and modeling. The obtained results show that the nano-biodegradable exhibited alkaline pH above 10 that keeps the drillpipe and equipment from the corrosion. The developed WNBPs exhibited a significant role in improving the rheological properties of the reference drilling fluid but not effective as CMS. The maximum gel strength of 957.6 pa was obtained from adding 2 wt% WNBPs and increased 1100 pa when temperature increased to 70 °C. Meanwhile, the same wheat nanoparticles enabled increasing the plastic viscosity from 0.03 to 0.09 pa.s and decreased to 0.07 pa.s under the influence of high temperature. In terms of the thinning behavior, the prepared wheat powders exhibited a significant role in providing the thinning behavior of the developed drilling fluids compared with the reference drilling fluid and CMS-modified drilling fluid. Adding 2 wt% WNBPs to the reference drilling fluid decreased the fluid loss from 19.5 to 14 mL but fine WPs have a stronger effective on the filtration properties and lowered the filtration rate to 11.5 mL.