Spatial heterogeneity of modern carbonate systems: Implications for reservoir complexity

RANKEY, EUGENE C., Comparative Sedimentology Laboratory/RSMAS University of Miami, Miami, FL 33149
[email protected]

    In exploration, development, and production settings, a fundamental challenge is generation of accurate predictions of reservoir trends. Geologists have ample data on vertical stratigraphic patterns, but information on spatial heterogeneity generally is limited. The purpose of this presentation is to provide a brief overview of some of our recent work on modern carbonate systems from the Bahamas, Belize, and the Arabian Gulf that illustrate important concepts for reservoir characterization in ancient analogs.

    Multi-scale analysis of facies patterns using remote sensing data reveals several important points: 1) Trends in facies body orientation are highly variable, ranging from random to parallel to the shelf margin to perpendicular to the shelf margin, as a function of scale and context. These data illustrate the necessity of geologic insight and the importance of scale in prediction. 2) Clear scaling relations (expressed in terms of exponential length-frequency distributions for tidal creeks and fractal area-frequency distribution for facies bodies, for example) are prevalent in many systems. These relations suggest that by understanding characteristics of the largest features of a population (e.g., from seismic or well data), the attributes of smaller features can be predicted. 3) Facies need not be deterministically linked to water depth. The absence of relation urges caution in over-interpretation of water depth changes and cyclicity.

    Collectively, these data illustrate examples that describe the complexity of spatial patterns, providing both general concepts useful for geologic prediction and quantitative data that could be used in reservoir models.