Substitution of simulated well-cuttings for core plugs in the petrophysical analysis of dolostones: Permian San Andres Formation, Texas
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Petrophysical data on heterogeneous dolostone rocks of the San Andres Formation (Permian) of West Texas were obtained using a mercury porosimeter from two kinds of samples: (a) cylindrical core plugs and (b) chips (simulated well-cuttings). In both kinds of samples, dolomitized oolitic grainstones and dolomudstones showed characteristics of good reservoir rocks (medium to large, uniform-sized pore throats, and a high percentage of available pores). Data from both plug and chip samples yielded comparable capillary-pressure curves defining the tight caprock facies and locating the top of the porosity zone in the dolomudstone. Petrophysical data derived from plugs and chips are similar because micron-sized throats which control capillary effects are not affected by sampling processes. The experiments suggest that well-cuttings, which are inexpensive to collect, can provide representative samples for characterization of reservoir facies in the thick, heterogeneous carbonate sequence of the San Andres. Well-cuttings therefore deserve more attention as an alternative sampling material, especially in reservoirs where cores are not available.
KeywordsCapillary Pressure Petrophysical Property Brooklyn College Core Plug Mercury Porosimeter
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