How freely the molecules move
In a thin oil, molecules move freely and the NMR signal lasts. In a heavy, viscous oil, movement is restricted and the signal fades quickly. The relaxation time is therefore a quick, indirect measure of viscosity, and a change in the relaxation time shows that an additive, a solvent or a nanoparticle has changed how mobile the oil is.
Where it is used
- Crude oils and heavy oils
- Bitumen and residues
- Oils mixed with solvents, surfactants, polymers or nanoparticles for enhanced recovery
Typical tasks are comparing oils, screening additives for their effect on mobility, and following the change of a formulation with temperature.
From relaxation time to viscosity
The relaxation time or the distribution of relaxation times of the oil is measured. A calibration with oils of known viscosity turns relaxation times into estimates of viscosity, which is useful when many samples have to be compared quickly.
What it adds
- Small samples and little preparation
- No solvents, and dark or opaque samples are no problem
- Fast screening of many formulations
- Works over a range of temperatures with a temperature unit
Points that matter in practice
- The link between relaxation time and viscosity is empirical. It is valid for a family of similar oils and should be calibrated for each
- Oils with asphaltenes give broad distributions of relaxation times, which are not a single number
- Vanadium, nickel and iron compounds shorten the relaxation times
- The method is a screening tool. It does not replace rheology or tests that reproduce the conditions of the reservoir
From your question to a routine method
Describe your oils and your question. MSY Consulting runs feasibility measurements, plans the calibration with you, and supports the analysis until the method is part of your routine.
Let's talk about your application
Send an email describing your instrument and your application, and you will get a reply.
contact@msyconsulting.euMSY CONSULTING SAS · Wissembourg, France · LinkedIn