Rock physics relationships are an essential element in the evaluation and modeling of seismic attributes for hydrocarbon exploration, appraisal, and field development. Calibrating seismic amplitude response requires accurate predictions of the expected acoustic properties for reservoir rocks, non-reservoir lithologies (e.g., mudrocks), and pore fluids at varying conditions. Estimating seismic amplitude variation with offset (AVO), extraction of reservoir properties from seismic (inversion), and time-lapse (4D) responses is similarly dependent on reliable rock and fluid property information. To date, relatively more effort and research have been devoted to the rock physics behavior of clastic sediments than with efforts in carbonate (limestone, chalk, dolomite) lithologies.Using a variety of recent public domain data sets comprising porosity, velocity (P- and S-wave) and, in most cases, mineralogy and petrographic data, we create an extensive global data set and evaluate the importance of both mineralogy and pore type on the elastic properties behavior of carbonate core plugs. Results from this investigation clearly illuminate the potential for over-interpreting elastic properties behavior as a function of pore type(s) when mineralogy is not explicitly included in the analysis.Rock physics analysis using a combination of heuristic and theoretical models shows that mineralogy exerts a significant additional variation on velocity at a given porosity. Failure to account for mineralogy exacerbates inferences about the effect of pore type(s) made using a comparison of P-wave velocity to an inappropriate empirical model (Wyllie) that does not account for pore shape(s). In this analysis, extreme variability in carbonate velocity is observed in only portions of two data sets, when mineralogy is explicitly considered and robust models that account for inclusion (pore) shape are utilized. Results from this analysis result in a recommended workflow, including rock physics template and dry-rock modulus diagnostics, for the evaluation of lab-based carbonate rock physics data. The workflow is amenable to further integration with well-based data and other core-based petrophysical measurements (e.g., electrical properties).
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