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A New Approach to Applied Geochemistry in Reservoir Evaluation: An Integrated Multi-Mineral and Porosity Model


Lab-based geochemistry is routine and wellsite geochemistry is on the rise, and thus maximizing the value of these data is an important goal in reservoir analysis. Numerous geochemical methods (e.g. X-ray Diffraction (XRD), X-ray Fluorescence, (XRF) Inductively Coupled Plasma spectrometry (ICP), and LECO Total Organic carbon (TOC), are currently used to directly measure organic carbon content, mineralogy (XRD) or model mineralogy from elements (XRF and ICP). However, these geochemical datasets are often not used to their full potential, and in the case of XRD are typically only used to validate the mineral matrix from petrophysical interpretations. Lab-based methods are more direct measurements of the solid-phase matrix density (minerals plus kerogen), which can then be used with bulk density and fluid density to calculate a total porosity. We present an integrated multi-mineral and porosity model, which incorporates lab and/or wellsite geochemistry data with open-hole logging data (bulk density) to determine by volume percent (1) mineral components and (2) total porosity. The sum of the mineral components plus TOC and their respective densities define the solid-phase matrix density, this along with the bulk density and assumed (or calculated) fluid densities are used to estimate the total porosity. Volume percent of the mineral components and TOC are closed around the calculated porosity to generate the multi-mineral model. Given clay speciation, the determination of bound water may also be incorporated into the model, thus providing an estimate of movable fluids (effective porosity) in the reservoir.