Permeability and porosity images based on NMR, sonic, and seismic reflectivity: Application to a carbonate aquifer

a large distribution of pore sizes, ranging from microcrystalline to large vugs. Knowledge of these pore spaces and their connectivity is crucial to hydrocarbon reservoir characterization and to hydrogeological and near surface environmental applications. In this paper, we present permeability and porosity images based on crosswell seismic measurements integrated with well logs and petrography from a carbonate aquifer underlying Palm Beach County, Florida, U.S. Petrography and core analyses reveal relationships between the rock physical properties that control the compressionaland shear-wave velocities of the formation. In addition, core data and petrography characterized the matrix permeability and pore spaces as well as the lithology. The lithology integrated with well logs determined the hydraulic and rock properties of a 500-ft zone intercepted by a borehole. We delineated vuggy and permeable/impermeable zones at the borehole and interwell scales in the upper Floridan aquifer in south Florida by inverting reflection seismic data for impedance which, when correlated with borehole permeability and porosity logs, led to empirical relationships that are used to transform impedance images to permeability and porosity images. The images showed continuity between the major geologic units and lateral changes in the porosity image. The high-resolution reflections observed at the field scale in the carbonate formation are associated with changes in porosity due to the presence of vugs. This was corroborated with P-wave and borehole data, which showed that, as P-wave velocity decreases, porosity increases. The images show that porous zones in the carbonate aquifer are laterally continuous up to 200 ft from the well and then become relatively discontinuous, and that these porous and permeable flow units are characterized by interconnected vugs.