Seismic Imaging of Gas Hydrate Accumulations Beneath Thick Permafrost Areas of the Mackenzie Delta, NWT, Canada

2012 ◽  
Author(s):  
G. Bellefleur ◽  
M. Riedel ◽  
T. Brent
Keyword(s):  
Gas Hydrate ◽  
Seismic Imaging ◽  
Mackenzie Delta

scholarly journals Implication of seismic attenuation for gas hydrate resource characterization, Mallik, Mackenzie Delta, Canada

2007 ◽  
Vol 112 (B10) ◽  
Author(s):  
G. Bellefleur ◽  
M. Riedel ◽  
T. Brent ◽  
F. Wright ◽  
S. R. Dallimore
Keyword(s):  
Gas Hydrate ◽  
Seismic Attenuation ◽  
Mackenzie Delta

Paleomagnetism of Canadian Arctic permafrost; Quaternary magnetostratigraphy of the Mackenzie Delta

1997 ◽  
Vol 34 (2) ◽  
pp. 135-139 ◽  
Author(s):  
Y. Wang ◽  
M. E. Evans
Keyword(s):  
Gas Hydrate ◽  
Accumulation Rate ◽  
Canadian Arctic ◽  
Major Change ◽  
Hydrocarbon Exploration ◽  
Mackenzie Delta ◽  
Natural Gas Hydrate ◽  
Polarity Reversals ◽  
Hydrate Reservoirs ◽  
Sedimentation History

A total of 357 samples taken from two long cores (Taglu, Kumak) drilled in the Mackenzie River delta have been investigated paleomagnetically. Remanence and susceptibility were measured in the field while the samples were still frozen. Profiles of susceptibility (5772 measurements) permit lateral correlation and imply that the average accumulation rate at Taglu was ~50% greater than that at Kumak, which lies 15 km to the southwest. Polarity reversals were found in both cores. The Matuyama–Brunhes boundary occurs at depths of 152 and 111 m at Taglu and Kumak, respectively; corresponding depths for the Gauss – Matuyama boundary are 356 and 243 m. In addition to the major chrons, we also find evidence of the Olduvai and Jaramillo subchrons. The chronology based on these data suggests that a major change in sedimentation history occurred about 1.5 Ma ago. This feasibility study thus suggests that paleomagnetism has chronological potential in permafrost environments that are currently important in frontier hydrocarbon exploration and as natural gas hydrate reservoirs.

Amplitude and frequency anomalies in regional 3D seismic data surrounding the Mallik 5L-38 research site, Mackenzie Delta, Northwest Territories, Canada

Geophysics ◽  
2006 ◽  
Vol 71 (6) ◽  
pp. B183-B191 ◽  
Author(s):  
M. Riedel ◽  
G. Bellefleur ◽  
S. R. Dallimore ◽  
A. Taylor ◽  
J. F. Wright
Keyword(s):  
Northwest Territories ◽  
Gas Hydrate ◽  
Seismic Data ◽  
Ratio Method ◽  
Unfrozen Water ◽  
3D Seismic ◽  
Mackenzie Delta ◽  
Data Set ◽  
Seismic Amplitude ◽  
3D Seismic Data

Amplitude and frequency anomalies associated with lakes and drainage systems were observed in a 3D seismic data set acquired in the Mallik area, Mackenzie Delta, Northwest Territories, Canada. The site is characterized by large gas hydrate deposits inferred from well-log analyses and coring. Regional interpretation of the gas hydrate occurrences is mainly based on seismic amplitude anomalies, such as brightening or blanking of seismic energy. Thus, the scope of this research is to understand the nature of the amplitude behavior in the seismic data. We have therefore analyzed the 3D seismic data to define areas with amplitude reduction due to contamination from lakes and channels and to distinguish them from areas where amplitude blanking may be a geologic signal. We have used the spectral ratio method to define attenuation (Q) over different areas in the 3D volume and subsequently applied Q-compensation to attenuate lateral variations ofdispersive absorption. Underneath larger lakes, seismic amplitude is reduced and the frequency content is reduced to [Formula: see text], which is half the original bandwidth. Traces with source-receiver pairs located inside of lakes show an attenuation factor Q of [Formula: see text], approximately half of that obtained for source-receiver pairs situated on deep, continuous permafrost outside of lakes. Deeper reflections occasionally identified underneath lakes show low-velocity-related pull-down. The vertical extent of the washout zones is enhanced by acquisition with limited offsets and from processing parameters such as harsh mute functions to reduce noise from surface waves. The strong attenuation and seismic pull-down may indicate the presence of unfrozen water in deeper lakes and unfrozen pore water within the sediments underlying the lakes. Thus, the blanking underneath lakes is not necessarily related to gas migration or other in situ changes in physical properties potentially associated with the presence of gas hydrate.

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