Over the last decades, biodiesel-based drilling fluids have drawn attention of researchers due to their biodegradability, low cost, high flash point compared to other synthetic-based drilling fluids. This review study discusses the development of biodiesel-based drilling fluids and analyzes the characteristics of biodiesels (based on the required range of values for their properties) that lead to better understanding in choosing the proper biodiesel for the drilling fluids. Although, using biodiesels as the base oil in drilling fluids, showed a favourable performance, it still poses some technical challenges such as excessive viscosity, poor pour point, low hydrolytic stability and water-in-biodiesel emulsion stability. In this study, recommended solutions including chemical modification of biodiesel's molecular structure, additives and mixing with other oils are presented. It was highlighted that the modification of biodiesel structure or the use of additives can be expensive and promote incompatibility with the other drilling fluids components. On the other hand, blending biodiesels with other base oils, showed promising solutions for the challenges of high viscosity, poor pour point and hydrolytic stability. It was found that the environmentally-friendly oils to mix with biodiesels, are synthetic esters, paraffins and linear alpha olefins. Furthermore, recent studies have suggested the use of nanomaterials (with hydrophobic characteristics) to stabilize water-in-biodiesel emulsion drilling fluids.
- Drilling fluids
- nano materials