--> The Mallik Gas Hydrate Field: Lessons Learned From 30 Years of Gas Hydrate Investigation, by Scott R. Dallimore, T. S. Collett, T. Uchida, M. Weber, A. Chandra, T.H. Mroz, E. M. Caddel, T. Inoue, H. Takahashi, A.E. Taylor, and the Mallik Gas Hydrate Resea; #90035 (2004)

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THE MALLIK GAS HYDRATE FIELD: LESSONS LEARNED FROM 30 YEARS OF GAS HYDRATE INVESTIGATION

Scott R. Dallimore1, T. S. Collett2, T. Uchida3, M. Weber4, A. Chandra5, T.H. Mroz6, E. M. Caddel7, T. Inoue3, H. Takahashi8, A.E. Taylor9 and the Mallik Gas Hydrate Research Team 
1 Geological Survey of Canada, P.O. Box 6000, Sidney, B.C., V8L4B2, Canada;
2 U.S. Geological Survey, Denver, CO, USA;
3 Japan National Oil Corporation, Chiba, Japan;
4 GeoForschungsZentrum Potsdam, Potsdam, Germany;
5 Ministry of Petroleum and Natural Gas, New Delhi, India
6 U. S. Department of Energy, Morgantown, WV, USA;
7 BP Canada Energy Company, Calgary, AB, Canada;
8 Japan Petroleum Exploration Company, Tokyo, Japan ;
9 Mallik Secretariat, Sidney, BC, Canada

The Mallik gas hydrate field is located at the edge of the Mackenzie Delta and the Beaufort Sea in Canada’s Northwest Territories. The gas hydrate deposits consist of an interbedded sequence of highly concentrated gas-hydrate-bearing sands from 890 m to 1106 m depth within the crest of a regional anticline feature. Ground temperature conditions of this terrestrial gas hydrate occurrence are similar to many offshore gas hydrate settings. However, at Mallik ~600 m of permafrost condition the ground temperatures rather than cold sea bottom temperatures found offshore. Quantitative well log analyses and core studies have documented numerous discrete gas hydrate layers exceeding 110 m in total thickness. High gas hydrate saturation values, that in some cases exceed 80% of the pore volume, establish the Mallik gas hydrate field as one of the most concentrated gas hydrate reservoirs in the world. The abundant geologic and engineering data available at the site, the advantageous logistics presented by its terrestrial location, and the similarities to many offshore gas hydrate occurrences make the Mallik site a very desirable location for gas hydrate research and development.

The Mallik site has a long history of gas hydrate investigation. The first documentation of their occurrence was made by Imperial Oil Ltd. during the course of drilling of the Mallik L-38 exploration well during the winter of 1972. At a time when gas hydrates in nature were primarily a scientific curiosity, Imperial Oil engineers identified the presence of gas hydrates through interpretation of their unusual open hole well log response, gas flows observed during drilling, and the results of closed chamber production tests. In the early 1990s, Canadian and international interest in gas hydrates from an energy and environmental perspective led the Geological Survey of Canada to undertake a regional appraisal of gas hydrates in the Mackenzie Delta area, mapping the geothermal and geologic factors controlling their occurrence. Through the initiative of Japan’s 1995-2000 gas hydrate research program, interest in the Mallik site was renewed in 1998. At that time the Japan National Oil Corporation (JNOC) and the GSC formed a partnership to advance gas hydrate drilling, coring, geophysics and scientific research objectives. JNOC and GSC, working with the Japan Petroleum Exploration Company, JAPEX Canada Ltd., the U.S. Geological Survey (USGS) and several other research institutions completed the 1998 Mallik 2L-38 gas hydrate research well program. While the program was a great success with numerous new scientific advances, no gas hydrate production testing was undertaken at that time.

The Mallik 2002 Gas Hydrate Production Research Well Program was undertaken with a primary goal to conduct the first modern production testing of gas hydrates. The program participants include 7 partners: GSC, JNOC, GeoForschungsZentrum Potsdam (GFZ), USGS, United States Department of the Energy (USDOE), India (Ministry of Petroleum and Natural Gas (MOPNG)/Gas Authority of India (GAIL)) and a industry joint venture party (made up of Chevron Canada Resources, BP Canada Energy Company and Burlington Resources Canada Ltd.). In addition, the project was accepted as part of the International Continental Scientific Drilling Program (ICDP); this allowed for considerable strengthening of the scientific team and a broadening of the scientific goals to include climate change studies. A unique aspect overall was the integration of science and engineering through the implementation of a diverse, multidisciplinary research program. To this end, numerous novel geophysical experiments were conducted, continuous cores were collected through the gas hydrate interval and several long duration climate and environmental studies were initiated.

Field work for the Production Research Well Program began in December 2001 and continued to the middle of March 2002. Two 1188 m science observation wells and a 1166 m production research well were drilled and instrumented. Full-scale field experiments in the production well monitored the physical behavior of the hydrate deposits in response to depressurization and thermal stimulation. The observation wells facilitated cross-hole tomography and vertical seismic profile experiments (before and after production) as well as the measurement of in situ formation conditions. Other aspects of the field program included the collection of gas hydrate-bearing core samples and downhole geophysical logging. A post-field research program included laboratory and modeling studies to document the sedimentology, physical/petrophysical properties, geophysics, geochemistry, microbiology and production behavior of the Mallik gas hydrate accumulation. The research team included some 100 participant scientists and engineers from over 20 institutes in 7 countries.