abstract
This paper presents some new concepts in the petroleum systems of the northern Labrador and southern
Baffin Island offshore region of eastern Canada. The focus of this work is the region of the Hekja O-71 gas
discovery of 1979 by Aquitaine, one of only five wells drilled between 1976 and 1980 within an area
covering some 166,000 square kilometers within the Saglek Basin.
This study emerged from a broad scale re-examination of the petroleum potential of this area “from
the crust up” using regional reflection, refraction and potential field data. An opportunity to use SAR
(synthetic aperture radar) data from the RADARSAT-1 Earth observation satellite was taken to incor-
porate alternative data sources to support this exploratory review and resource assessment.
Examination of the final map of interpreted slick-like features on the sea surface, revealed a close
correlation of some of these occurrences to several bathymetric features which have underlying seismic
signatures similar to previously identified gas hydrate “pipes” or chimney anomalies as seen in data from
offshore Nova Scotia and in the Irish Sea. Globally, many active marine hydrocarbon seeps appear on the
seafloor as “pockmarks”; in this case no seafloor depressions were seen on conventional multi channel 2-
D seismic data associated with active seepage. Instead, very distinct mound-like structures are seen
associated with seeps at two locations east of Hudson Strait. The presence of significant cold water coral
in close proximity to the active seepage sites may show a link between seafloor petroleum seepage and
coral reef development similar to that observed offshore Norway.
Close examination of the near surface seismic character led to the interpretation of what was originally
seen as seismic noise in vintage data, as likely being fluid escape chimneys or gas pipes, along the eastern
edge of the Hekja structural complex, where favourable hydrocarbon trapping conditions are present.
No active seeps were seen there; this may be due to other factors, such as the nature of the fluids that
are escaping or the possibility of self sealing activity by biological agents such as bacterial matting with
associated carbonate hard-ground formation.
One seep anomaly was noted relatively close to the major basaltic eruptive complex near the Gjoa G-
37 well. This may be due to the presence of volcaniclastic- hosted hydrocarbons similar in style to those
recently discovered at the Rosebank field in Paleocene volcanics in the Faroe-Shetland Basin. The
occurrence of an active seep in a volcanically-dominated terrain raises the potential for a radical shift in
accepted types of petroleum leads and where they may occur.
The presence of apparent oil seepage versus the past history of finding only gas-prone accumulations
is a strong indicator that a second, oil-prone petroleum system exists in the Saglek Basin. The signs of
active petroleum systems as shown by oil seep anomalies with confirming seismic evidence of discrete
sea floor structures in close proximity makes a compelling argument for re-examining these areas with
an eye towards stratigraphic instead of structural plays.