Investigation of Biodiesel-Based Drilling Fluid, Part 2: Formulation Design, Rheological Study, and Laboratory Evaluation

This paper presents an environmentally friendly, biodiesel-based invert-emulsion drilling fluid (BBDF). On the basis of the stable emulsion previously optimized (which was presented in Part 1), several necessary additives, including an organophilic clay (OC), a fluid-loss (FL) -control agent and a rheological modifier (RM), were developed or selected to formulate the BBDF. Numerous laboratory tests of different properties were conducted to evaluate the properties of this drilling fluid. BBDF has a rheological behavior and filtration properties that meet the requirements of drilling operations. It exhibits good shale-inhibition ability, excellent lubricity, and tolerance to contaminants. Low toxicity and great biodegradability are the prominent advantages of this system. After evaluating the suitabilities of known rheological models for BBDF, a hydraulic simulation was carried out on the basis of the Herschel-Bulkley model. BBDF performs similarly to conventional oil-based drilling fluids (OBDFs) subject to deepwater drilling conditions. High performance and great environmental compliance make BBDF a promising option for marine or extended-reach drilling. In addition, novel OC produced from rec-torite and nonionic surfactants was successfully introduced into this drilling fluid. This modified rectorite is expected to be a substitute for conventional organobentonite.