Hydrocarbon potential of the deepwater Scotian Slope

Abstract

The Canada-Nova Scotia Offshore Petroleum Board has recently completed a geological basin evaluation and numerical assessment of the hydrocarbon potential for the deep-water slope region, offshore Nova Scotia. The Scotian Slope lies in water depths of 200 to 4000 metres and extends 850 kilometers from the United States international border in the southwest, to the Newfoundland provincial border in the northeast. Within this region, no previous resource assessments have been published. This basin evaluation is based on the interpretation of 30,000 kilometers of regional 2-D seismic data, with stratigraphic correlations to shelf wells, industry seismic lines, deep crustal regional seismic data, and Deep Sea Drilling Project well-bores. The major challenge was mapping the top and base of the ubiquitous , mobile Argo Salt. Twelve hydrocarbon play types were identified throughout the region. All are salt-related to varying degrees. Suprasalt minibasins and salt flank plays for Cretaceous and Tertiary age reservoirs are widespread, as well as sub-salt plays. Some of these plays are well defined, others less so. Geochemical models were created and included three known source rocks and three potential source rocks. All are interpreted to have undergone maturation and expelled significant quantities of oil and gas. The stochastic numerical analysis employed probability distributions for all input parameters. Local data were used wherever possible, plus other data from global analogue basins. The assessment results are presented as probability distributions for oil, gas, solution gas, and natural gas liquids for each of the 12 plays, and, a statistically summed total. Both in-place and recoverable hydrocarbon resource values were generated. Because the petroleum system(s) have yet to be proved in the deepwater slope, this analysis also included geological risk factors. The undiscovered gas potential for the deepwater Scotian Slope is forecast at 15 to 41 trillion cubic feet, depending on the assumed geological risk factors. Similarly, the undiscovered oil potential is 2 to 5 billion barrels. This oil potential is very significant, and conforms to the high oil-to-gas discovery ratios encountered in other deepwater areas of the circum -Atlantic region.