| dc.description.abstract | The Prince Colliery is located offshore of Point Aconi, Cape Breton , Nova Scotia. The
colliery is presently extracting coal from the Hub seam of the Marien Group, part of the
Carboniferous Sydney Basin. Directly overlying the Hub seam is a channel sandstone
body which contains formation water. Water was sampled directly from the roof before
mining as well as from collapsed areas (gob areas) after mining.
Two formation waters were identified, (1) a low salinity formation water with Na/Cl
ratios between 0.87 and 0. 72 and chloride concentrations up to 11 200 mg!L, (2) a high
salinity formation water with Na/Cl ratios between 0.6 and 0.7 and chloride
concentrations between 24 400 and 30 000 mg!L. Gob water samples have chemistries
similar to the high salinity formation water even at sampling depths similar to the low
salinity formation water. Gob water samples have Na/Cl ratios between 0.6 and 0.7 and
chloride concentrations up to 28 000 mg!L. The high salinity formation water and the
gob waters are enriched in Br.
A 24 cm mudstone divides the channel sandstone body overlying the Hub coal seam into
two sandstone units. The upper sandstone (8.56 m thick) has vertical permeabilities up to
20.9 mD and the lower sandstone (1.56 m thick) has vertical permeabilities up to 1.33
mD. A vertical salinity profile constructed from geophysical data for drill hole P6 reveals
the more saline formation water overlies the low salinity formation water.
The channel sandstone body or aquifer overlying the Hub coal seam is
compartmentalized by an area of low permeability which separates two distinct formation
waters.
The chemistry of the high salinity formation water suggests that it is related to lower
basinal brines. The low salinity formation water is a mixture of the high salinity
formation water and a dilute ocean water end member. Mixing probably took place
during geologic time. The gob waters are shown to be a mixture of these two formation
waters and not sourced by the overlying modem seawater. Mixing models completed for
the gob water samples support this conclusion.
Key Words: Compartmentalized, Formation Waters, Brine, Aquifer, Permeability,
Chloride, Bromide, Na/Cl ratio, Salinity, Colliery, Gob. | en_US |
