Viscosity Determination of Heavy Oil and Bitumen Using NMR Relaxometry

摘要

Knowledge of oil viscosity is important whenrnevaluating the potential for waterflooding or EORrnprocesses. In heavy oil and bitumen, it is especiallyrnimportant to obtain a measurement of oil viscosity, as itrnwill be much higher than water and most solvents. Inrnvery heavy and very light oils, however, obtaining arnlaboratory measurement is difficult and prone to error.rnNMR is presented as an attractive alternative method forrndetermining oil viscosity.rnSeveral correlations already exist for determining oilrnviscosity using nuclear magnetic resonance (NMR).rnSome of these correlations compare the geometric meanrnT2 relaxation time to oil viscosity, while others relaternviscosity to the apparent hydrogen indexl. This paperrnexamines these different models on a suite ofrnconventional and heavy oil samples. It is concluded thatrnnone of the existing models can accurately predict oilrnviscosity for both conventional and heavy oils, especiallyrnfor oils with viscosity higher than 20 000 cP.rnIt is observed that viscosity estimations using NMRrnare not dependent on temperature, within the temperaturernrange tested. All the measured oil samples show arncorrelation between oil viscosity and geometric mean T2,rnand also between viscosity and amplitude index. This isrnconsistent with what other experimenters have noticed.rnAn empirical model is developed, correlating oil viscosityrnto both of these parameters. Unlike previous models, thisrnmodel can accurately predict oil viscosity for bothrnconventional and heavy oil. The wider range of thisrnmodel makes it useful for laboratory analysis of oilrnviscosity using NMR.