Tech Paper Downhole Viscosity Measurement
Revealing reservoir fluid complexities and architecture.
The InSitu Density reservoir fluid density and viscosity sensor accurately measures hydrocarbon viscosity at reservoir conditions in real time. This newest member of the InSitu Fluid Analyzer real-time downhole fluid analysis (DFA) system further expands the scope of the detailed fluid fingerprint delivered while the tool is stationed at the formation, instead of waiting for discrete sample analysis from a laboratory.
Hydrocarbon viscosity is a fundamental physical property that governs reservoir deliverability, injection, sweep efficiency, and enhanced oil recovery (EOR) performance. Knowing the variation of viscosity with depth and laterally within a field gives significant insight as to commercial viability.
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.