Determining Heavy Oil Viscosity with NMR

A discussion of the use of NMR logging in determining heavy oil viscosities in the field.

Accurate determination of viscosity is essential in the successful recovery of heavy oil, and low-field nuclear magnetic resonance (NMR) is proving to be a great tool for estimating heavy oil viscosity in the field. Lab measurements of oil viscosity are more difficult to obtain as viscosity increases and heavy oil recovered from cores may have been altered during sampling and transport to the lab. The main appeal of NMR is that the measured signal comes from hydrogen, which is readily present in both oil and water found in hydrocarbon reservoirs. There is growing research and field application of NMR logging for the determination of in-situ heavy oil viscosities; one of our recent JPT feature articles It’s time for an Industry Initiative on Heavy Oil, by Ashok Belani, cites the improvement of the NMR logging response in heavy oil as a key and ongoing research success. Other interesting references include a recent feature article in Hart's E&P August 2006 edition, Listening to heavy oil echoes by Eric Murphy and  Advances in NMR Logging, SPE 89177-MS by Robert Freedman.

Jorge