Stratal and Petrophysical Complexity Expressed in Seismic Reflection Patterns within Isolated Carbonate Platforms

Abstract

Seismic data are fundamental tools for evaluating and exploiting hydrocarbon resources, yet how the heterogeneous nature of carbonates complicates imaging, interpretation, and predictability of reservoir properties from seismic data is poorly understood. To test the hypothesis that changes in geologic inputs create a statistically distinct impact on seismic character of isolated platforms, this project generated synthetic seismic volumes from geologic models in which geologic heterogeneities (e.g. vertical and lateral trends in facies, porosity, and impedance) were isolated and varied, and their seismic impacts evaluated. Twenty-eight geologic scenarios, each of which addresses a single variable of geologic heterogeneity, form the basis for qualitatively illustrating the influence of stratal and petrophysical complexity on seismic volumes. The geological and petrophysical inputs are derived from modern and ancient analogs that capture a range of depositional and petrophysical variability. Subtle seismic reflection patterns captured by seismic attributes facilitate quantitative insights for understanding the relationship between geology and seismic character. Exploring statistical distinctions among scenarios reveals the capability for attributes to predict rock properties (e.g., average porosity) accurately in certain geological models. Qualitative results illustrate the seismic character of models in which stratigraphic architecture and petrophysical complexity varied reveals marked differences in phase and amplitude leading to both accurate and inaccurate geological interpretations. Quantitative results illustrate that as the type of geological heterogeneity changes, the quality of prediction between attributes and average porosity (expressed on a trace-by-trace, and net pore volume basis) also varies, emphasizing the importance of geology on attributes. These results provide insights into the complex controls on the seismic character of isolated platforms and potential pitfalls in interpretation.