This paper describes a low-impact, nonaqueous drilling fluid (LIDF) designed to minimize equivalent circulating density (ECD) increases and associated risks in deep water by reducing the effect of cold temperature on fluid viscosity. The fluid offers a superior low-viscosity profile and rapid-set, easy-break gel strengths while maintaining low shear-rate viscosity at high temperatures with optimal-weight material suspension. Field application demonstrated that the LIDF reduced the effect of temperature on the fluid rheological properties and minimized the risk of induced formation losses. These same rheological features reduced nonproductive time (NPT) associated with cement displacement and barite sagging.
Introduction
The extreme conditions to which an offshore drilling fluid is subjected pose numerous challenges to achieving appropriate formulation.
