
%0 Journal Article
%A Middleton, M.F. 
%A Winkler, D. 
%A Bick, M. 
%A Sahlin, T. 
%T Magnetic signatures produced by fluid flow in porous sediments
%J Exploration Geophysics
%D 2000/06/01
%V 31
%N 2
%P 413-417
%K 
%R https://doi.org/10.1071/EG00413
%U https://www.publish.csiro.au/paper/EG00413 
%X Laboratory experiments have demonstrated that a magnetic field is created during the displacement of water by oil in a porous medium. This magnetic field is interpreted to be generated by the electrokinetic effect. The results of the experiments are up-scaled to permit modelling of the electrokinetic-magnetic field generated by a producing oil field. Predicted maximum magnetic anomalies (measured at the Earth's surface) near oil wells, where the oil-water contact moves vertically at rates between 1 to 5 m/yr (conventional production rates), are in the vicinity of 1 nT or less. However, in the situation where producing wells have unstable pressure regimes, vertical flow rates can exceed 100 m/yr for short periods; maximum magnetic anomalies in the vicinity of 150 nT are predicted under such conditions. Accepting the interpretation that the electrokinetic-magnetic field is produced by randomly changing current loops in the partially oil-saturated zone (transition-zone) of the reservoir, the observed magnetic field is expected to exhibit time-transient behaviour. It is proposed that such a technique could be used to monitor changes to the pressure regime in producing petroleum reservoirs. 
