oa Delivering an efficient, robust and comprehensive petrophysical evaluation in carbonate environments

Several researchers have shown that petrophysical properties in carbonates are strongly correlated to pore microgeometry. Therefore, accurate petrophysical evaluation requires the integration of texture-sensitive logs such as nuclear magnetic resonance (NMR), borehole images and full waveform acoustic logs. Lithology and porosity evaluation in the presence of anhydrite requires the use of capture spectroscopy logs. A comprehensive and accurate petrophysical evaluation of carbonates requires the use and integration of a large suite of logs. As a result, an easy-to-implement workflow is needed to rapidly and reliably integrate all this data. This presentation shows an interpretation methodology and workflow that facilitates the easy integration of logging measurements essential to accurate carbonate evaluation. The workflow, which is the result of decades of research into carbonate petrophysics, shows that the method provides a rapid, robust, and comprehensive petrophysical evaluation including lithology, porosity, tar quantification, poregeometry evaluation, permeability and rock types, fluid saturations, relative permeability, and primary drainage capillary pressure curves. Examples are presented from major Middle East carbonate reservoirs. We also present<br>a software implementation that leverages the methodology through an intuitive and user-friendly workflow, enabling the delivery of a comprehensive report ontime. The method has been applied on several wells in the Middle East within a few hours of the receipt of log data at the processing center. On a couple of the wells the results were available before the tools had been pulled out of the well, permitting decisions on subsequent data acquisition and on the completion of the well.