Gulf of Mexico Gas Hydrate Joint Industry Project Leg II: Initial Results from the Green Canyon 955 Site

McConnell, Daniel S.; Collett, Timothy S.; Boswell, Ray; Frye, Matthew; Shedd, William; Dufrene, Rebecca Surcouf; Godfriaux, Paul; Mrozewski, S.; Guérin, Gilles; Cook, Ann Jennalie; Jones, Emrys

doi:10.2523/20801-ms

Cited by 9 publications

(15 citation statements)

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“…Due to the high gas hydrate saturations (>80 vol %) calculated mostly for low‐topographic areas, sediment porosity and permeability are strongly reduced which effectively blocks fluid flow through the pore space and additional methane supply from underlying layers, thereby creating local overpressures to evolve due to the presence of a free‐gas phase. These modeled gas hydrate saturations are consistent with findings at the GC955‐Q well indicating the presence of free gas directly underneath abundant gas hydrate accumulations located at the base of the GHSZ [ Guerin et al ., ; Hutchinson et al ., ; McConnell et al ., ].…”

Section: Resultsmentioning

confidence: 80%

“…The presence of gas hydrate deposits (both pore space-filling and fracture-filling) has been confirmed in the Green Canyon area [Boswell et al, 2012a[Boswell et al, , 2012bHutchinson et al, 2009;Lee and Collett, 2012;McConnell et al, 2010;Zhang et al, 2011] by seismic data analysis (abundant high-amplitude geophysical responses, continuous and discontinuous BSRs after Shedd et al [2012]), geochemical data and wellbore LWD measurements (JIP Leg II resulting in GC955-H, GC-955-I, and GC955-Q drill sites with locations shown in Figure 1). In addition, widespread gas hydrate occurrence in the Green Canyon region has been postulated based on Geochemistry, Geophysics, Geosystems 10.1002/2017GC006876 the presence of porous sandy layers close to the base of the GHSZ and highly permeable pathways for gas and fluid migration.…”

Section: Presence Of Gas Hydratesmentioning

confidence: 80%

“…According to the drilling reports [ Guerin et al ., ; Hutchinson et al ., ; McConnell et al ., ], borehole GC955‐I encounters the base of the GHSZ at a depth of 444 mbsf, and the borehole GC955‐H at a depth of 450 mbsf which is in good agreement with our predictions of the base of the GHSZ ranging between 439 and 458 mbsf (GC955‐I) and between 435 and 459 mbsf (GC955‐H). The deepest sediment depth drilled by well GC955‐Q most likely did not reach the lower boundary of the GHSZ [ Collett et al ., ]; however, the base of the GHSZ base was estimated to be at the depth of 461 mbsf which is in accordance with our numerical predictions (i.e., 445–467 mbsf).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the majority of present‐day gas hydrates in the area is relatively young and of biogenic rather than of thermogenic origin (see Figure ). These results are consistent with findings of the JIP Leg II cruise [ Guerin et al ., ; Hutchinson et al ., ; McConnell et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…The presence of gas hydrate deposits (both pore space‐filling and fracture‐filling) has been confirmed in the Green Canyon area [ Boswell et al ., , ; Hutchinson et al ., ; Lee and Collett , ; McConnell et al ., ; Zhang et al ., ] by seismic data analysis (abundant high‐amplitude geophysical responses, continuous and discontinuous BSRs after Shedd et al . []), geochemical data and wellbore LWD measurements (JIP Leg II resulting in GC955‐H, GC‐955‐I, and GC955‐Q drill sites with locations shown in Figure ).…”

Section: Study Areamentioning

confidence: 99%

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3‐D basin‐scale reconstruction of natural gas hydrate system of the Green Canyon, Gulf of Mexico

Burwicz

Reichel

Wallmann

et al. 2017

Geochem Geophys Geosyst

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Our study presents a basin‐scale 3‐D modeling solution, quantifying and exploring gas hydrate accumulations in the marine environment around the Green Canyon (GC955) area, Gulf of Mexico. It is the first modeling study that considers the full complexity of gas hydrate formation in a natural geological system. Overall, it comprises a comprehensive basin reconstruction, accounting for depositional and transient thermal history of the basin, source rock maturation, petroleum components generation, expulsion and migration, salt tectonics, and associated multistage fault development. The resulting 3‐D gas hydrate distribution in the Green Canyon area is consistent with independent borehole observations. An important mechanism identified in this study and leading to high gas hydrate saturation (>80 vol %) at the base of the gas hydrate stability zone (GHSZ) is the recycling of gas hydrate and free gas enhanced by high Neogene sedimentation rates in the region. Our model predicts the rapid development of secondary intrasalt minibasins situated on top of the allochthonous salt deposits which leads to significant sediment subsidence and an ensuing dislocation of the lower GHSZ boundary. Consequently, large amounts of gas hydrates located in the deepest parts of the basin dissociate and the released free methane gas migrates upward to recharge the GHSZ. In total, we have predicted the gas hydrate budget for the Green Canyon area that amounts to ∼3256 Mt of gas hydrate, which is equivalent to ∼340 Mt of carbon (∼7 × 1011 m3 of CH4 at STP conditions), and consists mostly of biogenic hydrates.

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Section: Resultsmentioning

confidence: 80%

Section: Presence Of Gas Hydratesmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

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3‐D basin‐scale reconstruction of natural gas hydrate system of the Green Canyon, Gulf of Mexico

Burwicz

Reichel

Wallmann

et al. 2017

Geochem Geophys Geosyst

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Archie's Saturation Exponent for Natural Gas Hydrate in Coarse‐Grained Reservoirs

2018

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Accurately quantifying the amount of naturally occurring gas hydrate in marine and permafrost environments is important for assessing its resource potential and understanding the role of gas hydrate in the global carbon cycle. Electrical resistivity well logs are often used to calculate gas hydrate saturations, Sh, using Archie's equation. Archie's equation, in turn, relies on an empirical saturation parameter, n. Though n = 1.9 has been measured for ice‐bearing sands and is widely used within the hydrate community, it is highly questionable if this n value is appropriate for hydrate‐bearing sands. In this work, we calibrate n for hydrate‐bearing sands from the Canadian permafrost gas hydrate research well, Mallik 5L‐38, by establishing an independent downhole Sh profile based on compressional‐wave velocity log data. Using the independently determined Sh profile and colocated electrical resistivity and bulk density logs, Archie's saturation equation is solved for n, and uncertainty is tracked throughout the iterative process. In addition to the Mallik 5L‐38 well, we also apply this method to two marine, coarse‐grained reservoirs from the northern Gulf of Mexico Gas Hydrate Joint Industry Project: Walker Ridge 313‐H and Green Canyon 955‐H. All locations yield similar results, each suggesting n ≈ 2.5 ± 0.5. Thus, for the coarse‐grained hydrate bearing (Sh > 0.4) of greatest interest as potential energy resources, we suggest that n = 2.5 ± 0.5 should be applied in Archie's equation for either marine or permafrost gas hydrate settings if independent estimates of n are not available.

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Predicting saturation of gas hydrates using pre-stack seismic data, Gulf of Mexico

2010

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Gulf of Mexico Gas Hydrate Joint Industry Project Leg II: Initial Results from the Green Canyon 955 Site

Cited by 9 publications

References 0 publications

3‐D basin‐scale reconstruction of natural gas hydrate system of the Green Canyon, Gulf of Mexico

3‐D basin‐scale reconstruction of natural gas hydrate system of the Green Canyon, Gulf of Mexico

Archie's Saturation Exponent for Natural Gas Hydrate in Coarse‐Grained Reservoirs

Predicting saturation of gas hydrates using pre-stack seismic data, Gulf of Mexico

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