Borehole fluid enters a hollow tube that surrounds an insulated rod at the center. The tube wall and the insulated rod form the electrodes of a capacitor. As hydrocarbons and water have different dielectric constants, the capacitance is a function of the dielectric constant of the fluid between the rod and wall of the tube. This capacitance is incorporated in the frequency determining circuitry of an oscillator. The frequency of the oscillator is therefore a function of the type of fluid that is present in the borehole.
The dielectric constant of water is 80, oil is around 10 and air has a value of 1. Salinity has minimal effect on tool measurement. The enhanced measurement has improved response characteristics particularly at water holdup values greater than 50%. The improved design also minimizes the “watering out” effect that can, under certain circumstances, result in a capacitance tool continuing to read water even though the surrounding fluid has been replaced by hydrocarbons.
- Improved response compared with earlier generation capacitance sensors
- Two phase production profiling
- Water holdup calculations
- Qualitative Analysis of high GOR wells
- Simultaneous operation with other GE production logging tools