Electrical anisotropy of gas hydrate-bearing sand reservoirs in the Gulf of Mexico

Cook, Anne E.; Anderson, Barbara I.; Rasmus, John; Sun, Keli; Li, Qiming; Collett, Timothy S.; Goldberg, David S.

Abstract:

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, R_| and the resistivity of the current flowing perpendicular to the bedding, R_|. We find the sandreservoir in Hole AC21-A to be relatively isotropic, with R_| and R_| values close to 2 Ω m. In contrast, the gashydrate-bearingsandreservoirs in Holes GC955-H and WR313-H are highly anisotropic. In these reservoirs, R_| is between 2 and 30 Ω m, and R_| 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.

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Article

ProdID:

70040079

Citation Author:

Cook, Anne E.; Anderson, Barbara I.; Rasmus, John; Sun, Keli; Li, Qiming; Collett, Timothy S.; Goldberg, David S.

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Central Energy Resources Science Center

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English

Citation Larger Work Title:

Marine and Petroleum Geology

Citation LatN:

0302300

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0181000

Citation LonE:

-0810200

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-0975100

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Citation Phsyical Description:

13 p.

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Elsevier

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Citation Search Results Text:

Electrical anisotropy of gas hydrate-bearing sand reservoirs in the Gulf of Mexico; 2012; Article; Journal; Marine and Petroleum Geology; Cook, Anne E.; Anderson, Barbara I.; Rasmus, John; Sun, Keli; Li, Qiming; Collett, Timothy S.; Goldberg, David S.