Print this pageA Natural Seepage of Biogenic Natural Gas at Tatogga Lake in the Intermontane Belt (Bowser Basin) of the Canadian Cordillera
Carol A. Evenchick1, Kirk G. Osadetz2, Bernard
Mayr3, Fil Ferri4, and Mark Hayes5
1 Natural Resources Canada, Vancouver, BC
2 Geological Survey of Canada, Calgary, AB
3 University of Calgary, Calgary, AB
4 BC Energy and Mines, Victoria, BC
5 Geoscience Section, Victoria, BC
On November 17, 2003 Tatogga Lake was visited to observe a reported gas seepage Several circular or oval openings in the ice were present from the dock area (UTM zone 9, 440378/6396983, NAD27) to at least 100 m northeast of the dock, along a northeast trending belt roughly 20 to 40m from the eastern shore. The openings ranged from individual holes about 15 to 30 cm diameter, to coalesced holes a couple of metres long. One open patch with surface activity was about 1 x 2 m in size, and 30 m northeast of the dock. Closer inspection revealed that it was actually three coalesced openings resulting from bubbles rising from 3 places. The bubbles were about 3 - 8 mm diameter. When a sample was collected from this seep it took about 3 or 4 periods of streams of bubbles to fill about 1/3 of the 125 ml bottle, over a total of about 3 or 4 minutes. A sample of head space gas was recovered from 1 of 2 isolated holes nearby where bubbles were about 5 -10 mm in diameter. A third sample was recovered from the northeastern-most stream of bubbles in the large hole. The gas is composed essentially of methane and carbon dioxide. The carbon isotopic composition of the gases indicate that they are produced by biogenic processes.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005