1. n. [Production Logging]
A device for measuring the average density of the fluid at different depths in a completed production or injection well to produce a fluid-density log. Knowing the density of the individual phases allows their holdups to be determined, directly in the case of biphasic flow, and in combination with other measurements for triphasic flow. Introduced in the late 1950s, the gradiomanometer measures the pressure difference between two pressure sensors, placed approximately 2 ft [0.6 m] apart. The pressure difference reflects the average fluid density across the well within that depth interval. The resolution is high, around 0.005 g/cm3, but the accuracy can be affected by a friction effect, a kinetic effect and well deviation. The effect of deviation can be corrected, but the sensitivity to holdup is reduced as the deviation increases until it is zero in a horizontal well. Note: Gradiomanometer is a mark of Schlumberger. It is now a commonly accepted term for a certain tool that measures differential pressure.
See related terms: holdup log, nuclear fluid densimeter, production log
