Investigating the impact of viscosifier concentrations on hydraulic horsepower at the bit

This study focuses on optimizing the rheological properties of drilling mud by incorporating Xanthan gum at two concentrations (6 g and 12 g) to improve flow behavior, cutting transport, and hydraulic horsepower efficiency. The mud samples were analyzed using the Power Law and Herschel-Bulkley models to determine the most accurate representation of their rheological behavior. The Herschel-Bulkley model provided a better fit for both concentrations, with higher R² values and lower sum of square errors (SSE) compared to the Power Law model. For the 6 g Xanthan gum sample, the fluid behavior index (n) was 0.476, indicating shear-thinning properties and the yield strength (τ_y) was 2.112 lbf/100 ft². In contrast, the 12 g sample exhibited a higher yield strength of 14.142 lbf/100 ft² and a fluid behavior index closer to 1 (n = 0.965), suggesting shear-thickening behavior. The hydraulic horsepower analysis indicated that the 6 g mud was more efficient at higher flow rates, maintaining a consistent increase in horsepower up to 800 gpm. The 12 g mud, on the other hand, exhibited higher viscosity and increased pressure losses, resulting in a decrease in efficiency at flow rates exceeding 400 gpm. Both mud samples showed shear-thinning characteristics, but the 6 g formulation was better for transporting cuttings under dynamic conditions, while the 12 g formulation excelled in suspending cuttings during stagnant periods, due to its higher yield strength. Further optimization revealed that the 6 g mud was suitable for larger nozzle sizes and higher flow rates, with an optimum flow rate of 800 gpm, while the 12 g mud, with its increased viscosity, performed better with smaller nozzle sizes and flow rates around 400 gpm. This study highlights that the 6 g Xanthan gum mud is ideal for high-flow-rate operations, offering better cutting transport capabilities, while the 12 g mud is more effective in ensuring cuttings suspension when circulation ceases. These findings provide crucial insights for selecting optimal drilling mud formulations, considering both cutting transport and suspension requirements based on specific operational needs.