Abstract

One of the applications of production logging is to find the source of oil, water or gas production. In order to solve this problem, the two most important parameters are holdup (volume fraction) and fluid velocity of each phase.

The gradiomanometer is used in production logging for holdup measurements. Knowing the holdup, the dispersed phase velocity is derived from an empirical chart. Because of the low contrast between the oil and water density, gradiomanometer cannot accurately provide water holdup in the extreme high or low water cut wells.

Fluid density from the gradiomanometer is derived from the pressure measurements in two fixed ports. In high flow rate and deviated wells, gradiomanometer reading is affected by friction and tool deviation.

The Digital Entry Fluid Imaging Tool (DEFT^#) holdup measurement is based on four low frequency (LF) probes. These probes discriminate between electrically conductive and non-conductive fluid. Since, water is a conductive medium in producing oil or gas wells, the probes discriminate between water and oil or gas.

Water holdup for each probe is computed as a function of time the probe spends in water. The output is in binary, that is, 1 for the time spent in oil bubble and 0 for the time spent in water. There is approximately 10⁹ contrast between the oil and water electrical conductivity. Because of the digital output, no master or well site calibration is required.

Because of the high water cut, commingled production and high flowrate, Caltex Minas Field was chosen as the Field Test site. This paper describes Field Testing experience of Digital Entry Flow Imaging Tool (DEFT^#) in Minas Field.