Investigation of Biodiesel-Based Drilling Fluid, Part 1: Biodiesel Evaluation, Invert-Emulsion Properties, and Development of a Novel Emulsifier Package

As a type of mono-alkyl ester, biodiesel exhibits great potential to serve as the base oil of drilling fluids substituting for conventional oil-based drilling fluids (OBDFs). This paper presents a series of laboratory investigations of water-in-biodiesel (invert) emulsion as the basis of a high-performance, environmentally friendly, and low-cost biodiesel-based drilling fluid (BBDF). Biodiesel produced from waste cooking oil was used to formulate a BBDF because of its high flashpoint, reliable storage stability, acceptable elastomeric material compatibility, nontoxicity, and excellent biodegradability. In light of the results of tests used to measure various properties, the biodiesel invert-emulsion chemistry, including the required hydrophile/lipophile balance (HLB), optimal emulsifier, effects of different additives (organophilic clay, calcium chloride, and lime), as well as hydrolytic stability, was studied. A biodiesel invert emulsion that remains stable after hot rolling at 120 degrees C for 16 hours can be prepared with correct combinations of additives, thereby offering a firm foundation for designing BBDFs. The novel emulsifier package developed in this work is introduced as an achievement in the comprehensive usage of waste cooking oil because its feedstock is identical to that of biodiesel. An initial economic analysis of the use of biodiesel for drilling is also presented. Details of the formulations and properties of BBDFs derived from this fundamental research are discussed in another paper (Part 2).