Abstract: A method for selecting a demulsifier for breaking a water-in-oil emulsion employs at least two electrodes to be immersed in a plurality of emulsion samples, each having a different demulsifier added. The current flow between the electrodes is recorded for each sample. The demulsifier producing the most rapid rate of change of current flow is identified as the most effective demulsifier in breaking the water-in-oil emulsion.

Abstract: In a system for logging while drilling, a downhole turbine is rotated by the hydraulic power in the circulating drilling fluid to provide mechanical power that is converted to regulated DC power. The DC power is converted to two-phase AC power by a DC/AC motor drive. The frequency of the two-phase AC power output of the DC/AC motor drive is modulated by the output of a downhole transducer which monitors a selected downhole condition. A two-phase AC induction motor is driven by the DC/AC motor drive at a speed which changes with the frequency modulation of the two-phase AC power. The induction motor drives an acoustic transmitter which interrupts the circulating drilling fluid to produce an acoustic wave in the drilling fluid that is frequency modulated in response to changes in the condition being measured by the downhole transducer.