NMR METHODS FOR IMAGING OF TRANSPORT PROCESSES IN MICRO-POROUS SYSTEMS

Magnetic resonance imaging (MRI) allows non-destructive and non-invasi ve measurement and visualisation of both static and dynamic water phen omena. Flow and transport processes can either be measured by followin g the local intensity in time-controlled sequential images, by mapping the effect of contrast agents or labelled molecules, or by mapping th e (proton) displacement in a well known time interval directly. By a p roper choice of methods, a time window ranging from milliseconds to we eks (or even longer) can be covered. Combining transport measurements with relaxation time information allows the discrimination of transpor t processes in different environments or of different fluids, even wit hin a single picture element within an image. Here we present an overv iew of the principles of NMR imaging techniques to visualise and unrav el complex, heterogeneous transport processes in porous systems. Appli cations and limitations will be discussed, based on results obtained i n model and artificial soil systems. (C) 1997 Elsevier Science B.V.