Rock physics-based seismic trace analysis of unconsolidated sediments containing gas hydrate and free gas in Green Canyon 955, Northern Gulf of Mexico

Subsurface gas hydrates in the northern Gulf of Mexico

“…However, the available data indicate high S h to a drilling depth of at least 2444 m (8017 ft: Collett et al, 2012). As discussed above, seismic data analyses conducted post-drill suggest that the well may have penetrated (or approached closely) free gas-bearing sands Zhang et al, 2012). The results of the drilling in GC955 are generally consistent with the exploration model, with strong leading peak amplitudes delineating thick gas hydrate occurrences within sands (Fig.…”

“…21), and include juxtaposed leading peaks and troughs, suggesting complex, patchy occurrences of gas hydrate and free gas (see Zhang et al, 2012;Shelander et al, 2012). The GC955-H well is located on the flank of the dome, and targeted a leading peak event about 2 km 2 (500 ac) in size at a projected depth of w410 mbsf (1350 fbsf).…”

“…Once the LWD tool string was recovered, the drill pipe re-entered the hole and pumped 16.0 ppg mud followed by cement. Subsequent log and seismic data analyses suggest that a free gas zone likely is present at the site below the well-log inferred gas hydrate Zhang et al, 2012). It remains unclear whether the well penetrated into a gas-bearing zone or if communication with a slightly deeper gas accumulation was created by the well control procedures .…”

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

“…Drilling issues necessitated withdrawal of the LWD string prior to full penetration of the reservoir unit, therefore the gamma-ray and other data were not collected to the total depth of the well. block H) and free gas (as in the accumulation drilled at Well Q) accumulations occurring locally (see Zhang et al, 2012), likely reflecting local variation in the effectiveness of both gas hydrate and fault-defined traps.…”

“…The anticlinal structure within the southwestern corner of GC955 contains several other seismically-imaged accumulations (see Zhang et al, 2012), although the additional resources associated with those deposits are not estimated here.…”