Application of Membranes to Treatment of Water Based Exploration and Production Wastes

Produced water and spent drilling fluids from petroleum operations represent a significant expense to companies developing new energy reserves. These spent fluids, seldom recycled, offer a viable source of water resources for oil-field reuse. A major obstacle to reuse is the presence of suspended solid material in the fluids. Such contaminants, if not removed, will not only prevent any reuse but will also impede disposal. The objective of this project was to evaluate membrane filtration as a way to remove suspended and entrained particles to produce re-useable effluents using membranes. Ceramic and Polyvinylidene Flouride (PVDF) hollow fibre membranes were used in laboratory scale experiments in the investigation of the colloidal filtration of field produced spent drilling fluids and produced water. Feed parameter and operational parameter evaluation of ceramic and PVDF hollow fibre membrane filtration of spent drilling fluids and produced water showed that feed concentration, solids in the spent drilling fluid and oil in the produced water, is the most important parameter during membrane filtration. Operational parameter variation showed that high cross flow velocity was beneficial in flux maintenance during spent drilling fluid filtration due to its high solids concentration because of the scouring effect on the cake layer on the membrane surface. Pressure regimens were important in flux decline as relatively high pressures accelerate the consolidation of the concentration polarization layer causing flux decline. High temperatures were generally beneficial for increased flux in the filtration of produced water and spent drilling fluids. Resistance calculations were used to deduce the contribution of individual resistances during the ceramic filtration of produced water and spent drilling fluids and were identified as a real-time tool for monitoring membrane integrity and fouling. Backwashing as a fouling mitigation technique was effective in flux maintenance in ceramic membranes especially in the filtration of produced water; cleaning solutions were effective in flux recovery in ceramic membrane filtration and to a slightly lesser degree in hollow fibre membrane filtration. A methodology in determining the suitability of water based oil field wastes using membranes was developed to help future investigations of this type.