New techniques transform elemental oxides, derived from nuclear logging measurements, into a set of geologically viable mineral phases (mineral modes). Some of these different mineral transform methods are evaluated using a set of well-constrained laboratory measurements on North Sea reservoir core and synthetically produced rock samples. Mineral proportions derived from each transform model are compared with those from conventional petrographic techniques to evaluate and constrain each transform method. Emphasis has been placed on evaluating transform techniques using well constrained laboratory data before their application to logging tool measurements (such as elemental data derived from spectral logging tools). Applying correct mineral transforms to the logging environment will lead towards a continuous, accurate measurement of mineralogy downhole, especially with the introduction of higher resolution logging tools. The resulting mineralogy logs are potentially valuable on their own, especially for the quantification of clay minerals, but they can also be used to determine other formation descriptors such as grain density, porosity, and cation exchange capacity (CEC). In wells where core recovery is poor, they can help extend formation evaluation across these poorly defined zones, thus increasing the reservoir characterization available for exploration and appraisal.

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