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Cook, Ann Elizabeth et al. (2006): Cohesive strength of gas-hydrate-bearing marine sediments
Leg/Site/Hole:
Related Expeditions:
ODP 164
ODP 204
Identifier:
ID:
2008-126197
Type:
georefid
Creator:
Name:
Cook, Ann Elizabeth
Affiliation:
Columbia University, Palisades, NY, United States
Role:
author
Name:
Goldberg, David
Affiliation:
Schlumberger Doll Research, United States
Role:
author
Name:
Kleinberg, R. L.
Affiliation:
Role:
author
Identification:
Title:
Cohesive strength of gas-hydrate-bearing marine sediments
Year:
2006
Source:
In: Anonymous, AAPG 2006 annual convention; abstracts volume
Publisher:
American Association of Petroleum Geologists and Society for Sedimentary Geology, Tulsa, OK, United States
Volume:
15
Issue:
Pages:
21
Abstract:
We examine the relationship between gas hydrate saturation and the cohesive strength of marine sediments in a variety of continental margin settings. The cohesive strength (cohesion) is a fundamental physical property controlling sediment resistance to compressive failure. The cohesion (C (sub o) ) can be related to the dynamic Young's modulus (E (sub D) ), where: C (sub o) = 1.5*10 (super -3) E (sub D) . The dynamic Young's modulus is computed using in situ Vp, Vs, and bulk density borehole logs. The C (sub o) profiles are compared to estimates of the in situ hydrate saturation, S (sub h) , calculated using electrical resistivity logs and the modified Archie formula: S (sub h) = 1 - (aR (sub w) /Rp (super m) ) (super 1/n) . We will present results of these comparisons from data collected during: Ocean Drilling Program Legs 204 (at Cascadia margin) and 164 (at Blake Ridge); the JIP gas hydrate drilling project in the Gulf of Mexico; and Mallik permafrost wells. In general, C (sub o) steadily increases downhole as sediments compact due to overburden. In the marine sediment environments, cohesion ranges from 500-2000kPa above the BSR, with a baseline gradient between 5 and 10 kPa/m. Preliminary results at Cascadia margin show that in sediments with S (sub h) > 15%, C (sub o) increases dramatically, at least 200kPa greater than the general trend of the downhole gradient. This suggests that C (sub o) is affected directly by S (sub h) , and may be related to the rate of change in S (sub h) (e.g. gradual or sharp) as a function of depth. Further study on the relationship between C (sub o) and S (sub h) may provide information on the growth habit of gas hydrates in sediment pore spaces.
Language:
English
Genre:
Rights:
URL:
Coverage:
Geographic coordinates:
North:43.3000
West:-130.0000
East: -130.0000
South:43.3000
Keywords:
Economic geology, geology of energy sources; Atlantic Ocean; Blake-Bahama Outer Ridge; Cascadia Channel; cohesive materials; continental margin; depth; East Pacific; elastic constants; gas hydrates; Leg 164; Leg 204; marine environment; marine sediments; natural gas; North Atlantic; North Pacific; Northeast Pacific; Ocean Drilling Program; Pacific Ocean; petroleum; porosity; saturation; sediments; Young's modulus;
.
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