In all fields core represents such a minuscule percentage of the total rock volume that careful extrapolation of this data is critical. Wireline logs usually offer the best solution to this problem.
This becomes more important where the field has little or no core, poor seismic coverage, or where the stratigraphy is lithologically monotonous due to facies (e.g. massive oolites) or due to diagenesis (e.g. in coarse crystalline dolomites). In these cases we have extensive experience of undertaking field-wide studies using log-defined facies and sequence stratigraphic schemes, from which detailed models can be built and input into simulation models.
Many of our recent studies involve hundreds of wells through stratigraphies up to 1.5km thick; examples include the supergiant Cantarell field of Mexico.