Investigating the effect of high thermal–saline conditions on the rheological properties of waste vegetable oil biodiesel-based emulsion mud

Abstract

Tight environmental regulations coupled with the constant need to enhance water-based drilling mud performance for use in deeper formation where it can withstand high temperature, high pressure and high saline condition have always been an existential issue during drilling operations. This research compared the performance of biodiesel produced from waste vegetable oil with that of white oil 5#, used as additives in mud formulations. Their effectiveness was tested at high temperature high pressure, in the presence of monovalent and divalent electrolytes. The mud density, rheological behavior, yield point, fluid loss under high temperature and pressure, and cake thickness were examined. The biodiesel emulsion mud proved more stable compared to both the white oil emulsion mud and the water-based mud without oil additive under thermal and saline conditions. The biodiesel emulsion mud demonstrated low and stable mud viscosity under the different conditions studied. The fluid loss reduction was better for biodiesel emulsion mud with API fluid loss of 2.20 cm3 and high temperature high pressure filtration loss of 9.4 cm3, while white oil emulsion mud gave 6.40 and 18.40 cm3, respectively, for both parameters at 180 °C in calcium-contaminated mud. The biodiesel emulsion mud exhibited superior qualities of rheological properties compared to white oil emulsion mud at higher temperature and saline conditions. The rheological models of the white oil emulsion mud and biodiesel emulsion mud at room temperature followed Bingham plastic model, but at high temperature their rheogram approximated to Herschel–Bulkley model.