Core-derived acoustic, porosity & permeability correlations for computation pseudo-logs

Abstract

Abstract In order to improve hydrocarbon production, it is often necessary to obtain more accurate rock, fluid and petrophysical information. For example, to obtain a reservoir porosity map using seismic data as reference, it is necessary to generate reliable correlations between seismic attributes and petrophysical properties like porosity and permeability. Again, to optimize drilling and/or hydraulic fracturing programs, it is also necessary to estimate better formation static mechanical behaviour from geophysical data. The main goal of this work is to establish for an offshore Brazilian field, relationships between compressional and shear wave velocities and petrophysical properties such as porosity and permeability. The large number of limestone samples (120) gave us a precise empirical relationship between V s and V p for limestone. In order to obtain a calibration reference, we also made, with the same samples, simultaneous measurements of dynamic and static elastic constants. Using all these laboratory relationships, it was possible to generate unmeasured pseudo-logs of in situ parameters, which include: shear wave velocity, static and dynamic elastic constants and permeability. The good experimental relationships obtained between k -φ and V p-φ in this work together with available logs give us an additional method to estimate permeability which is impossible to obtain from in situ measurements.