Abstract: Complex impedance measured over a predefined frequency range is used to determine the identity of different oils in a column. The location of an interface between the oils is determined from the percent frequency effects of the complex impedance measured across the interface.

Abstract: A method for enhancing the resistivity contrasts of a thermal front in an oil recovery production field as measured by the CSAMT technique is disclosed. This method includes the steps of:(a) preparing a CSAMT-determined topological resistivity map of the production field;(b) introducing a solution of a dopant material into the production field at a concentration effective to alter the resistivity associated with the thermal front; said dopant material having a high cation exchange capacity which might be selected from the group consisting of montmorillonite, illite, and chlorite clays; said material being soluble in the connate water of the production field;(c) preparing a CSAMT-determined topological resistivity map of the production field while said dopant material is moving therethrough; and(d) mathematically comparing the maps from step (a) and step (c) to determine the location of the thermal front.This method is effective with the steam flood, fire flood and water flood techniques.

Abstract: Method and apparatus are provided for obtaining accurate dynamic measurements for passage of phase fronts through a core sample in a test fixture. Flow-through grid structures are provided for electrodes to permit data to be obtained before, during and after passage of a front therethrough. Such electrodes are incorporated in a test apparatus for obtaining electrical characteristics of the core sample. With the inventive structure a method is provided for measurement of instabilities in a phase front progressing through the medium. Availability of accurate dynamic data representing parameters descriptive of material characteristics before, during and after passage of a front provides a more efficient method for enhanced recovery of oil using a fire flood technique.