Gas hydrate resource potential in the Terrebonne Basin, Northern Gulf of Mexico

Architecture of gas-hydrate-bearing sands from Walker Ridge 313, Green Canyon 955, and Alaminos Canyon 21: Northern deepwater Gulf of Mexico

“…LWD data indicates that the porosity in the "blue" sands is approximately 33% at the H well and perhaps 39% where it exists at shallower depth in the H well Frye et al, 2012). In the "blue" unit, gas hydrate saturation (Sh: % of pore volume) commonly exceeds 60% and is greater than 80% in the better developed sands logged at the G well.…”

“…The JIP Leg II program accessed industry 3D seismic data for each site, and acquired only LWD data in the field; no core data are available to aid in the interpretation of the units drilled. Six gas-hydrate-bearing sand reservoirs discovered during JIP Leg II are described in this report: three separate sand-rich intervals (designated as "blue", "orange", and "green") as observed in WR313 Frye et al, 2012), the "H-" and "Q-fault-blocks" observed in GC955 (McConnell et al, 2010), and an extensive shallow sand body observed in AC21 . In this study, we reference the LWD data as well as interpretations determined from 3-D seismic datasets to support assessment of the depositional setting and reservoir architecture of each sand body.…”

“…In contrast to the basin floor setting of the GC955 site, both the WR313 and AC21 sites test seismically-defined targets where salt-withdrawal tectonics and rapid sedimentation favor the deposition of coarsegrained facies within channel, levee, and basin floor fan environments within "ponded" mini-basins on the GoM slope (Prather et al, 1998) inboard of the Sigsbee Escarpment. At the WR313 site, the JIP Leg II drilling targets within the Terrebonne basin are deeply buried (w870 m below the seafloor (mbsf): w2850 feet below seafloor (fbsf)) and occur near the inferred base of gas hydrate stability (BGHS; Shedd et al, 2010;Frye et al, 2012); whereas in the Diana basin at the AC21 site, the reservoir is relatively shallow (w180 mbsf; w590 fbsf) and located well within the gas hydrate stability zone (GHSZ; Frye et al, 2010). A description of Figure 1.…”

“…(For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) channel and on the northern channel margin (see Frye et al, 2012), although any potential gas saturation cannot be confidently assessed (Fig. 9).…”

Analysis on geologic conditions affecting the performance of gas production from hydrate deposits

“…For instance, the gas hydrate occurs in the coarse-grained turbidite sands in the eastern Nankai Trough and in the fine-grained clay-silts in Shenhu area of the South China Sea Zhang et al, 2007). The hydrate concentration is 14% at the Blake Ridge and over 40% with the average of 67% at the Gulf of Mexico (Paull and Matsumoto, 2000;Boswell et al, 2012;Frye et al, 2012). The thickness of the hydrate-bearing layer is about 10 m at the Site 3 and 25 m at the Site 7, although the sites are within a small area of Shenhu drilling area (GMGS1, 2007).…”