Scaling Up: Correlation of In Situ Hydraulic Conductivity with Depositional and Diagenetic Heterogeneity in Reefal Limestone
University of Miami, Rosenstiel School of Marine and Atmospheric Sciences, Marine Geology and Geophysics, Miami, FL USA
The Plio-Pleistocene reefs of the Southern Dominican Republic provide a unique opportunity to assess the petrophysical complexities associated with diagenetic progression and depositional heterogeneities in shallow-water carbonates. The challenge of predicting transport in carbonate rocks is one of characterizing the hydraulic conductivity (K) distribution at a scale that captures the variability of these heterogeneities.
These shallow-water carbonates are exposed as a series of stair-stepping clinoforms with the oldest at the highest elevation and the youngest closer to the coast. Vertical profiles of hydraulic conductivity where obtained by performing short-interval (~1 m) constant-head injections using an in-situ straddle-packer assemblage in the shallow section of two key (previously drilled) boreholes. The two boreholes where selected based on the difference in diagenetic overprint associated with age and episodes of stabilization.
In both boreholes the lowest values are associated with the surface calcrete. K increases below the exposure surface, with smaller downhole variations associated with facies distributions. The highest K values in core 1 and 4 are 0.18 cm/s and 0.15 cm/s, respectively. This increased fluid flow is associated with secondary macroporosity, for example, leached branching corals. The plug-based petrophysical properties from core, will provide a unique comparison of scales with the proposed borehole data. Some preliminary data shows a different trend when scaling up from plugs. When completed, the study will provide a facies/diagenesis/acoustic-based correlation of permeability (hydraulic conductivity) data after several stages of post-depositional stabilization. These correlations can then be used as formation properties in fluid-flow simulation models for shallow-water carbonates.
AAPG Search and Discovery Article #90183©2013 AAPG Foundation 2013 Grants-in-Aid Projects