S. Young, E. Stamatakis and A. Patel, MI SWACO
It has long been recognized that there exists a significant technology gap between the performance of the best water based drilling fluids (WBF) and invert emulsion fluids. WBF fall behind with respect to shale inhibition, wellbore stability, rate of penetration, and fluid stability. Strengthening of restrictions regarding use and discharge of invert emulsion fluids, coupled with the challenges of extended reach and deepwater drilling (low fracture gradients, narrow ECD windows, high lost circulation risk) have challenged WBF development. The results of several research and development projects into shale inhibition, cuttings accretion, lubricity, cuttings encapsulation and rate of penetration with WBF allowed the stepwise generation of a new WBF designed to approach invert emulsion fluid performance. This paper describes the development of a these inhibitive water based fluids, and the field performance results obtained from these fluids, showing the invert emulsion-like performance and discussing engineering of the new drilling fluid.