Synthesis and evaluation of selenium-doped nanocomposites in enhancing drilling fluid properties

Drilling operations increasingly face challenges related to poor rheology control, excessive fluid loss, and inefficient cuttings transport, especially in HPHT conditions. This study aimed to address these issues by developing a sustainable nanoparticle based additive synthesized through a green route. A biogenic extract from Pinus nigra pollen was used to produce selenium doped silver zinc oxide nanocomposites (Se@Ag/AgO–ZnO) via a single step co precipitation method. The resulting heterostructured material exhibited nanoscale crystallite size and a textured morphology confirmed by SEM. The nanocomposite was incorporated into water based drilling fluids at concentrations of 0 to 5000 ppm. Rheological behavior was evaluated using Bingham Plastic modeling, filtration performance was measured under standard and HPHT conditions, and cuttings transport was assessed through rolling oven tests. Results showed that the optimal concentration of 1000 ppm increased yield point to 12.12 Pa and plastic viscosity to 48.7 cP while maintaining high model accuracy with R2 values of at least 0.991. Filtrate volumes decreased by up to 68.5 percent in standard tests and 69.2 percent in HPHT tests due to formation of a compact and low permeability filter cake. Quartz and shale cuttings recovery reached 88 percent and 79 percent respectively at 1000 ppm. At 5000 ppm, mild performance decline was linked to particle agglomeration. These findings demonstrate that pollen derived nanocomposites can enhance drilling fluid behavior and offer a sustainable approach for improving rheology, filtration control, and hole cleaning efficiency.