Characterization and selection of novel magnetic tracers for dynamic heterogeneity identification and quantification

The substantial cost associated with the implementation of any enhanced oil recovery (EOR) program requires a robust understanding of the dynamic heterogeneity of the reservoir. The traditional methods used to determine the preferential flow paths are well-to-well transient pressure tests and tracer tests. This paper provides the results of a series of experiments with new types of magnetic tracers for the prediction of permeability heterogeneities and preferential flow paths in reservoir rock samples. Concentration prfile curves obtained for a number of new magnetic tracers are presented including water-based Ferro Fluids and water-soluble iron oxide powders. The magnetic properties of individual magnetic tracers are also presented which aid in the selection process of the optimum magnetic tracer. To confirm the validity of the results obtained from magnetic traces, we compare the results against conventional tracer methods on the same core plugs. The results show a very good agreement between the two methods. One of the advantages of the magnetic tracers is the reduced analysis time of the core and effluent samples. The magnetic tracers can also be used in situations where there are constraints with using conventional tracers, for example, due to various chemical reactions in the injection lines, and/or with reservoir minerals deeper in the ground. The results of the new magnetic tracers can help in better understanding of the reservoir heterogeneity and sweep efficiency when combined with existing methods such as pressure transient analysis.