(411d) Reclamation of Spent Drilling Fluids by Cross-Flow Microfiltration

Wu, Y., Praxair Inc

Oil- and synthetic-based drilling fluids can become contaminated with significant quantities of low-gravity solids, which cannot be removed by conventional solids control equipment and methods.  The accumulation of low-gravity solids degrades the performance of costly oil- and synthetic-based drilling fluids in several ways and often generates large quantities of spent drilling fluids not suitable for drilling activities. As a result of rigorous environmental regulations moving toward zero discharge, drilling wastes are the focus of attention in the oil and gas exploration industry.

In this research, pressure driven liquid-phase microfiltration (MF) was investigated  for the first time as a potential solution to the removal of low-gravity solids from spent oil- and synthetic-based drilling fluids, where fine solids are retained by the membrane and clean oil passes through the membrane and is recovered as permeate. The results demonstrated that cross-flow MF is capable of breaking the strong emulsions of drilling fluids and recovering clean base oil in the permeate, independent of drilling fluid formulation and composition while minimizing chemical handling and the variability in chemical-based processes. Understanding the impact of each operating parameter on permeate flux will allow us to realize the full potential of cross-flow MF as a spent drilling fluids treatment technology. In this study several operating parameters such as trans-membrane pressure, back-pulse, cross flow velocity and temperature were investigated to optimize permeate flux, minimize membrane fouling and maximize oil recovery using a membrane with a nominal pore size of 0.1 micron. A membrane-cleaning protocol for the fouled membranes was also developed.