Summary
This paper presents a novel technique to characterize detailed formation heterogeneity for a carbonate reservoir using measurements from electrode resistivity array (ERA), a wireline formation tester, and a permanent downhole pressure sensor. The ERA was installed on tubing in a barefoot well rather than permanently cemented outside the casing as in previous applications. This notable difference provided flexibility for device installation and operation but also introduced particular issues in the ERA data acquisition and interpretation. Furthermore, the ERA measurements were carried out in conjunction with low-salinity water injection and oil and water production in the same well. The primary finding presented in this paper is that the time-lapse ERA voltages near a source electrode showed unique characteristics that represented local formation heterogeneity. This localized sensitivity of ERA data allows detailed characterization of the formation heterogeneity within the length of the ERA string in the vertical direction and about 100 ft laterally around the wellbore. The scale size of the investigated formation heterogeneity is comparable to typical grid sizes used in current reservoir simulations. Models were developed to identify stratified permeability heterogeneities from the time-lapse ERA voltages. The stratified heterogeneity estimated from the ERA measurements was compared to and verified by openhole logs and core analyses data. The final heterogeneous reservoir model from the ERA was subsequently applied to a numerical simulation that integrated the dynamic fluid flow, salt transport, and electrode array responses for monitoring water-front movement and estimating multiphase formation properties. The history matching of the time-lapse ERA data confirmed the first pass estimates of the identified heterogeneities.