(562a) Downhole Oil/Water Separation Based on Hydrocyclones

Hydrocyclones were developed as inertial separators at the end of the 19^th Century. These separators are widely used to thicken liquid suspensions, clarify liquids, de-gas liquids, and classify solids. The internal flow structure within these confined vortex separators is incredibly complicated. Commercially available hydrocyclones have major diameters ranging from 10mm to more than 300mm. The hydrocyclone is used to separate two immiscible phases with different densities and with a dispersed phase particle size distribution between 5 and 500 microns. It is also used to classify solids suspended in a continuous liquid phase. Hydrocyclones may be operated either as â??reverse-flowâ? separators or as â??forward-flowâ? separators with or without an air core.

Although earlier studies in the 1950s demonstrated the utility (and promise) of hydrocyclones as liquid/liquid separators for concentrated and stable dispersions, the risk of forming an emulsion in high Reynolds number flows has limited the practical use of the hydrocyclone as a liquid/liquid separator to relatively dilute dispersions. Over the past 50 years, a few important practical commercial designs for deoiling produced water on offshore platforms have emerged. During the 1990s, high-capacity deoiling hydrocyclones were field tested as downhole oil/water separators (i.e., DOWS-technology); however, due to the risk associated with this technology, this initiative was abandoned.

This presentation will discuss the potential use of very small diameter, low-capacity hydrocyclones for downhole oil/water separation. The proposed approach aims to mitigate problems associated with single-stage, high-capacity hydrocyclones. Clearly, a viable DOWS technology would have a significant impact on oil and gas production worldwide.