Tech Paper Downhole Viscosity Measurement
Revealing reservoir fluid complexities and architecture.
InSitu Viscosity
Reservoir fluid viscosity sensor
In this composite DFA plot obtained by the InSitu Fluid Analyzer system from a deepwater well in the Gulf of Mexico, the measurements indicate that the top two stations consist of oil, the next station down is in water, and the bottom zone is oil. The optical density is much darker and the viscosity much higher in the lower oil-bearing sand than the upper sand, and their fluorescence values significantly differ. The presence of the water zone confirms that a barrier separates the two sands.
How it works
The miniaturized InSitu Viscosity sensor fits the sensor slots of the InSitu Fluid Analyzer system to provide viscosity measurements that cover the range of light to heavy oil in downhole environments: from 0.2 to 300 cP.
The sensor measures the viscosity of flowing fluid with a vibrating-wire (VW) method combined with well-established analytical equations. The measurement principle is based on the medium-dependent vibration characteristics of the sensing element. The more viscous the fluid, the more abruptly and rapidly the vibration of the VW sensing element lessens than compared with its behavior in a less-viscous fluid. Viscosity measurement requires density input from the InSitu Density sensor or manually entered.
The oleophilic properties of the sensor enable measuring the viscosity of formation hydrocarbons in the presence of up to 10% water, which makes representative measurement possible in immiscible contamination.
The log shows how the viscosity measurements correlate with the other sensor measurements, with the viscosity much higher in the lower oil-bearing sand than the upper sand.
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