In-situ Viscosity Using Low Field NMR: A Field Case Study

ABSTRACT

Low field nuclear magnetic resonance has been demonstrated to hold great potential as a tool for performing in-situ viscosity predictions. Previous experience has shown that low field NMR signals can be related to fluid viscosity, including high viscosity fluids like bitumen. A bulk liquid NMR model was developed that can make order of magnitude viscosity predictions for a wide range of samples from different fields in Alberta. The model can be tuned for individual oil fields to yield quantitative viscosity predictions with temperature. The same model has also been extended to predict viscosity of bitumen
solvent mixtures.

The present work details a series of laboratory measurements performed for specific wells in a heavy oil reservoir. NMR measurements were initially performed on core samples. The constituent heavy oil was later removed from the core and its viscosity was measured both with NMR and with conventional methods. The in-situ viscosity of the reservoir was then predicted. From the laboratory and field NMR measurements a
viscosity distribution “log” with depth was identified. The paper describes the algorithm followed and shows how such tests can be used to calibrate NMR logging data with respect to viscosity.

A full version of this paper is available on SCA Web Online.