Low field NMR is routinely used in the oil exploration industry to examine the T2 relaxation time distribution of fluids in core plugs. These distributions can be further interpreted to give information on pore size distributions, permeability, porosity, free fluid index and bound water volumes.
Instruments for routine measurements of relaxation distributions generally operate at 2MHz, in order to reduce artefacts caused by ferromagnetic material in the samples, and to mimic the operation of the NMR logging tools. Laboratory based instruments are used to help calibrate downhole logging tools, and for development of new pulse sequences and protocols for later application on the downhole logging tools.
Higher field instruments are also available for use in applications where greater sensitivity is required – for example, in diffusion or imaging studies.