HR: 14:50h
AN: S43A-06    [Abstracts]
TI: Geological Modeling and Property Scaling in Carbonates Based on Petrophysical Logs, Core Analyses, and Sequence Stratigraphy
AU: * Ward, W B
EM: ward@earthworks2020.com
AF: Earthworks, LLC, P.O. Box 178, Newtown, CT 06470-0178 United States
AU: Murphy, W
EM: murphy@earthworks2020.com
AF: Earthworks, LLC, P.O. Box 178, Newtown, CT 06470-0178 United States
AU: Nolen-Hoeksema, R
EM: rcnh@earthworks2020.com
AF: Earthworks, LLC, P.O. Box 178, Newtown, CT 06470-0178 United States
AU: Boyd, B
EM: beckett@earthworks2020.com
AF: Earthworks, LLC, P.O. Box 178, Newtown, CT 06470-0178 United States
AU: Fleming, G
EM: gfleming@earthworks2020.com
AF: Earthworks, LLC, P.O. Box 178, Newtown, CT 06470-0178 United States
AU: Murphy, W
EM: willmurphy@earthworks2020.com
AF: Earthworks, LLC, P.O. Box 178, Newtown, CT 06470-0178 United States
AB: Properties of carbonates are particularly sensitive to changes in rock fabric over the range of scales from at least 10^-6 to 10² meters. We have examined core and well logs from reservoirs and aquifers around the world including the Middle East and Florida. In all cases, the geology per se was important but undervalued in the engineering plans and specifications. We conclude that it is best to use high-resolution stratigraphic models to guide geologic correlation between boreholes using electrical borehole images, NMR logs, core description, and core analysis as well as seismic and pumping-test data if available. As required by the principle of mapping, all data must be georeferenced to a single reference frame. Sampling and observations must be at precise scales and locations. Uncertainties must remain explicit. We must preserve very small angles (ll0.5°) and determine orientations with respect to depositional dip. Statistical distribution of properties requires stationarity that is unlikely in carbonates. We have found that rigorous application of high-resolution sequence stratigraphy is key to solving real engineering problems in carbonates. It depends on accurate observation and interpretation of stratal surfaces and sequence boundaries. While the identifications are best on core, a combination of appropriate borehole logs has proven satisfactory. To extrapolate away from the borehole, we grow three-dimensional forms constrained by observed thicknesses, orientations, facies, accommodation space, and the a priori knowledge of natural occurrence. Viewing data in three-dimensions is advantageous, but the mathematical projection of three-dimensional forms proves preferable. After establishing geometries, we apply simple constitutive relations constrained within facies to produce synthetic elastodynamic logs at the scale appropriate for the sonic logs and various seismic measurements. The relations connect mineralogy, density and saturation to properties including seismic slownesses, elastic moduli, and permeability and their sensitivity to environmental conditions. Details in and among the cores and plugs are crucial to assigning properties correctly to facies within stratigraphic bodies.
DE: 0900 EXPLORATION GEOPHYSICS
DE: 1800 HYDROLOGY
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
SC: Seismology [S]
MN: 2005 Joint Assembly