If you don't mix it, you don't have to separate it. H. McKinzie et al. Paper. Proc. Conf., Multiphase Technology, pages 229--240. (See abstract 745 for complete reference).
With reference to the immense amount expended on chemicals and equipment, especially offshore, to re-separate oil and water, attention is drawn to prevention of the mixing by modifying the method of artificial lift. Several patented methods of artificial lift are described that reduce the amount of water lifted to the surface by using the wellbore as a separator, and handling oil and water separately. As these methods are adaptable to reverse coning applications, further advantages over conventional pumping are gained. Methods such as DAPS (dual action pumping system) which have been field tested with good results and several other newer pumping combinations are described. 3 refs.