Applicability of sawdust as a green additive to improve the rheological and filtration properties of water-based drilling fluid: an experimental investigation

Abstract Drilling fluid is essential to oil and gas drilling operations due to its diverse functionality. But the most commonly used drilling fluid additives are hazardous chemicals and are not biodegradable. As a result, the demand for environment-friendly additives has been raised to replace the hazardous chemical additives. Considering the rising interest toward green additive, this study examined the applicability of sawdust to be used as a biodegradable drilling fluid additive to improve the rheological and filtration properties of water-based mud. Sawdust was chosen for this study because of its high cellulose content, widespread availability, and low cost. Following the guidelines set by the American Petroleum Institute (API), we carried out laboratory experiments that encompassed three distinct concentrations of sawdust: sample 1 (with 0.25% sawdust), sample 2 (with 0.50% sawdust), and sample 3 (with 0.75% sawdust). The concentrations of sawdust were measured as a weight percentage of the total volume of the base water. Concentrations above 0.75% led to gelation issues. Results showed minimal impact on mud weight at 0.25% sawdust, while 0.50 and 0.75% concentrations caused slight weight reduction due to foam development. Plastic viscosity increased by 28.5, 42.8, and 71.4% for sample 1, sample 2, and sample 3, respectively, compared to the base mud. Sawdust-containing mud exhibited desirable gel strength and shear-thinning behavior. Moreover, sawdust significantly improved filtration properties by reducing fluid loss and mud cake thickness. Sample 2 (0.5% sawdust) performed well in terms of filtration properties. Mud cake permeability followed the trend: $${k}_{\mathrm{BM}}>{k}_{0.75\% \mathrm{sawdust}}>{k}_{0.25\% \mathrm{sawdust}}>{k}_{0.50\% \mathrm{sawdust}}$$ k BM > k 0.75 % sawdust > k 0.25 % sawdust > k 0.50 % sawdust . Based on promising laboratory performance, lower concentrations of sawdust are recommended as a cost-effective and eco-friendly additive to enhance rheological and filtration properties of water-based drilling fluid systems.