Wireline NMR Combined With Azimuthal Logs Define Flow Capacity and Homogeneity within High Angle Geothermal Well

Abstract

Geological, geophysical, geomechanical and petrophysical data gathering and analysis are important to manage Geothermal resources optimally. We highlight a case where a unique log combination was run to assess lateral homogeneity and flow potential in the target aquifer. A highly deviated well was drilled through a thin bed structure to characterize producing limestone layers within a carbonate sequence. The evaluation program included LWD nuclear data recorded while geosteering and Wireline NMR and advanced dipole sonic which were successfully tractor conveyed to verify the homogeneity of thin and highly porous and mobile diatomite and their performance. This was the first application of NMR logs to establish porosity and permeability in a Geothermal project. The NMR log results provided accurate information that complemented the sonic and density images adding critical knowledge of the mixed layers. Those logs integration helped to define the heterogeneity of target reservoirs, quantify critical rock parameters, and ability to transport the fluids. Azimuthal sonic data was explored adding to the overall understanding of different measurements and obtain a more detailed structural model. This also allowed to understand whether permeability variations were truly related to layer variations or a result of the measurements sensing properties of an adjacent layer.