Drilling fluids were formulated from biomaterials such as Brachystegea eurycoma and Detarium micocarpum. The laboratory measurements were carried out, and their rheological properties then evaluated. The drilling properties such as yield point, apparent viscosity, and low shear rate yield point were determined from the experimental data. The field polypac additive that is currently in use was formulated and used as control sample to biomaterial products. Both were supplemented with equal concentrations of XC polymer additive and potassium chloride, weighted up with calcium carbonate and barite. Herschel-Buckley model was used to obtain the yield stress. Regression line was established. Plots of cutting transport ratio versus fluid flow rate, and cuttings concentration versus average annular velocity of the biomaterial mud and the existing polypac mud were made at both low and high flow rates for 8½ inch hole diameter. The biomaterial mud was compared with the existing polypac mud and results show that yield stress for low solids, and barite weighted muds are 36 and 30 lbs/100 ft2 for biomaterial muds, respectively. The results for low solids and weighted muds of the existing polypac muds also show the yield stress of 35, 26 and 6 lbs/100 ft2 for both regression lines. The plots of transport ratio versus fluid flow rate and cuttings concentration versus annular velocity for both biomaterial mud and the existing Polypac mud gave the same trend. Both mud types show good hole cleaning at high flow rates and small diameter holes. The investigations also show that biomaterial products are not commercially available to be used in preparing drilling fluids.
Key words: Biomaterial mud, Polypac mud, Brachystegea eurycoma, Detarium micocarpum.