Print this pageA petrophysical-based method of defining hydraulic flow units was utilized to develop the reservoir zonation within a sequence-stratigraphic framework for the San Andres Formation at Vacuum Field, New Mexico. The San Andres Formation consists of platform and shelf margin carbonates that have undergone substantial diagenesis including dolomitization, karstification, and cementation. Flow units were characterized within high-frequency carbonate sequences by analyzing the vertical variation of flow capacity (kh), storage capacity (fh), and pore-throat radius (R35) associated with vertical successions of subtidal, intertidal, and supratidal lithofacies. Capillary pressure measurements, thin sections, and SEM images obtained from core plugs that represent observed pore types were used to estimate the radius of pore throats. Pore-throat radius values from cored wells were used to modify the empirically-derived Winland equation in order to estimate values of pore-throat radius in non-cored wells. The combined sequence-stratigraphic framework and petrophysical-based zonation were used to build a three-dimensional geologic model without upscaling prior to flow simulation.
Reservoir parameters were estimated among wells and within flow units by integrating multicomponent seismic data. Seismic attributes, including amplitude, reflection strength, and shear-wave anisotropy, were used to develop a calibration function to populate the geologic model in the interwell space. Shear-wave anisotropy computed across the reservoir interval was used to map lateral changes in fracture density. These trends were used to bias estimates of permeability within the model. In addition, by incorporating shear wave with compressional wave data, improved porosity estimates were achieved.
AAPG Search and Discovery Article #90925©1999 AAPG Foundation Grants-in-Aid