--> Abstract: New Techniques And Technology For Geological Assessment, Formation Evaluation And Testing Of Vuggy And Moldic Reservoir Facies, by Roy D. Nurmi; #90928 (1999).

Datapages, Inc.Print this page

NURMI, ROY D.
Schlumberger, Houston, TX

Abstract: New Techniques and Technology for Geological Assessment, Formation Evaluation and Testing of Vuggy and Moldic Reservoir Facies

Vuggy and moldic pore systems in exploration wells and carbonate reservoirs are often not very well defined by standard formation evaluation techniques, because porosity alone is not enough. However, even the latest technologies and developments do not eliminate the need for thorough multidisciplinary examination of geology, logging, testing and production data, which allow characterization and practical classification of pores that are present in complex carbonates.

Borehole imagery and coring both have limitations for vug and/or moldic facies characterization, generally being inadequate for determining the pore system extent and connectivity. Coring is often limited by incomplete recoveries of thin leached horizons or vuggy intervals as the small volume of a core often precludes assessment of vug connectivity. The identification of vugs or molds using borehole resistivity imagery is sometimes very subjective and, thus, conductive features are often misinterpreted as vugs. In addition, workstation software for quantification of vugs commonly provides misleading indications of connectivity. Although nuclear magnetic resonance can only quantify small vugs and molds, it defines the critical pore system within the surrounding rock volume.

Wireline well testing tool improvements, including dual packers allow isolation of vuggy and thin, high permeability streaks present in supergiant reservoirs as well as small mound structures. This data defines the significance and whether they extend away from a well. Thus, a key to evaluating possible thin, laterally extensive high permeability layers is well testing and/or special production monitoring of multiphase flow, but the decision of where, what and how to test complex dual-permeability systems requires informed geological input.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas