--> ABSTRACT: Integration of New Well Logging Technology (NMR and Imagery) to Better Evaluate Geological Facies and Potential in Middle East and other Carbonate Reservoirs, by R. Nurmi; #91021 (2010)

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Integration of New Well Logging Technology (NMR and Imagery) to Better Evaluate Geological Facies and Potential in Middle East and other Carbonate Reservoirs 

NURMI, ROY

Geological characterization of carbonate reservoirs has improved with advances in technology, techniques, and integration of data. The combination of borehole imagery from horizontal wells with 3-D and/or 4-D seismic has revealed the presence and nature of unsuspected reservoir faulting and fracturing in many Middle East reservoirs. Equally important has been the evaluation of thin high-permeability layers by high resolution nuclear magnetic resonance which dramatically impact reservoir behavior.

Borehole nuclear magnetic resonance, a new high-resolution well logging technology is revealing pore sizes and size distributions to better define effective porosity, even with an abundance and variety of micropores present. it also has been possible to better evaluate complex reservoir facies through the integration of NMR and borehole electrical imagery with other logs and/or core. This assessment included thin porosity layers, heterogeneous patchy or convoluted mixtures, complex Tertiary and Cretaceous karst fills, and vuggy and fractured facies in many formations. NMR defines pore size distributions while electrical imagery reveals megapores and the surrounding matrix including the decimeter-scale porosity distribution. This approach revealed some thin, lower porosity layers to be the most permeable, while the highest porosity layers in one northwest Arabian reservoir were comprised of micropores forming unsuspected porous barriers or baffles. Importantly, zones with very high-water saturations were correctly predicted to flow oil without water in Middle Eastern Arab and Thamama reservoirs, as well Paleozoic and Tertiary reservoirs elsewhere. 

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.