Barbara I. Anderson John Rasmus Keli Sun Qiming Li Timothy S. Collett David S. Goldberg Anne E. Cook 2012 We present new results and interpretations of the electricalanisotropy and reservoir architecture in gashydrate-bearingsands using logging data collected during the Gulf of MexicoGasHydrate Joint Industry Project Leg II. We focus specifically on sandreservoirs in Hole Alaminos Canyon 21 A (AC21-A), Hole Green Canyon 955 H (GC955-H) and Hole Walker Ridge 313 H (WR313-H). Using a new logging-while-drilling directional resistivity tool and a one-dimensional inversion developed by Schlumberger, we resolve the resistivity of the current flowing parallel to the bedding, <i>R</i>_&#124; and the resistivity of the current flowing perpendicular to the bedding, <i>R</i>_{<u>&#124;</u>}. We find the sandreservoir in Hole AC21-A to be relatively isotropic, with <i>R</i>_&#124; and <i>R</i>_{<u>&#124;</u>} values close to 2 &Omega; m. In contrast, the gashydrate-bearingsandreservoirs in Holes GC955-H and WR313-H are highly anisotropic. In these reservoirs, <i>R</i>_&#124; is between 2 and 30 &Omega; m, and <i>R</i>_{<u>&#124;</u>} is generally an order of magnitude higher. Using Schlumberger's WebMI models, we were able to replicate multiple resistivity measurements and determine the formation resistivity the gashydrate-bearingsandreservoir in Hole WR313-H. The results showed that gashydrate saturations within a single reservoir unit are highly variable. For example, the sand units in Hole WR313-H contain thin layers (on the order of 10-100 cm) with varying gashydrate saturations between 15 and 95%. Our combined modeling results clearly indicate that the gashydrate-bearingsandreservoirs in Holes GC955-H and WR313-H are highly anisotropic due to varying saturations of gashydrate forming in thin layers within larger sand units. application/pdf 10.1016/j.marpetgeo.2011.09.003 en Elsevier Electrical anisotropy of gas hydrate-bearing sand reservoirs in the Gulf of Mexico article