Heterogeneity Analysis of Oil Sands Cores

ABSTRACT

Thermal recovery of bitumen in oil sands requires the ability to propagate steam within the formation, and to have drainage of heated fluids to production wells. As such, reservoir heterogeneities can play a very significant role in these processes. Many of these heterogeneities are not easy to define at the scale of logging tools. The objective of this study is to develop a work flow and set of output parameters that can provide a much higher resolution characterization of heterogeneities present in an oil sand, based on non-destructive testing of core. Oil sands cores with variable quality of sand and shale were acquired and tested using an ensemble of techniques including CT scanning at 1mm intervals, continuous NMR and EM sweeps. The continuous NMR is done by moving the core in 1 cm intervals and then de-convoluting the signal from subsequent echo trains to extract information in high resolution. The EM sweeps are done using two different designs of probes (one induction and one plate design). Density and porosity are extracted from CT. Oil and water contents are extracted from NMR and CT porosity. Resistance is extracted from the induction probe and frequency dependent capacitance is extracted from the plate probe. All the information is then reprocessed together to extract a number of data in a high resolution log of the core. Although the initial interest is in the quantitative distribution of the V-shale parameter, the results can be used to characterize heterogeneity in both porosity and fluid distributions within the core.

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