The Kotaneelee Gas Field, Yukon Territory: An "HTD"-Type Liard Basin Dolomite Play
David
W. Morrow
Geological Survey of Canada, Calgary,
AB
The Kotaneelee Gas Field, presently the only producing gas field in the Yukon Territory, was discovered in 1977 and was tied in to the Westcoast Transmission system in 1979. There are 2 producing wells, one salt-water disposal well and 3 abandoned wells in the field with a total original gas in place (OGIP) of 400 Bcf. The porous Manetoe Dolomite, a regionally extensive diagenetic replacement dolomite developed within the Devonian carbonate of the Mackenzie Platform, forms the reservoir host rock. Gas in the Kotaneelee Field is trapped beneath impermeable Devonian shale in a faulted structural culmination. Kotaneelee Field is similar to other Liard gas fields, which all fall along an exploration fairway of particularly thick Manetoe Dolomite extending northeast towards Nahanni Butte. Cores from the H-38 well display fabrics typical of the brecciated and vuggy dolomitized fabrics in many “hydrothermally” dolomitized reservoirs with white dolospar-cemented “tight” mosaic and rubble packbreccias. The finely to medium crystalline replacement component of the Manetoe dolomite in the Kotaneelee Field is generally fabric destructive and commonly non-mimetic, but bioclasts are commonly preserved as white dolospar-cemented molds, or as open vugs. Some cemented vugs contain probable geopetal internal sediments. White dolospar within incompletely cemented vugs commonly displays the characteristic curved crystal faces of “saddle” dolomite. Fluid inclusion and stable isotope data indicate dolomite precipitation from hot hypersaline Ca-Mg-Cl brines.
AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005