Development of the Petroleum System on the South Labrador Slope

Abstract

Exploration offshore Labrador has been confined to the shelf with no test of the slope or basin floor. The hydrocarbon potential on the shelf has been proven by 6 gas discoveries. There have been no significant oil discoveries to date. The objective of this study was to investigate the potential for an ‘Oil Story’ in sector NL01-LS in the Labrador Sea based on recent sea floor sampling results, the interpretation of recently acquired seismic data, well interpretation and basin and thermal modelling. A sequence stratigraphic interpretation and play fairway analysis of the Labrador passive margin was conducted by TGS in 2013/2014 on a regional multi-client 2D seismic data set (22,167 km) and 31 wells on the shelf. In 2014 TGS acquired infill seismic lines (4,600 km over the NL01-LS sector in the South Labrador Sea and to tie to 4 additional wells on the Labrador shelf. The regional interpretation over this sector was updated, and a detailed stratigraphic and structural interpretation with a leads catalogue and supporting AVO analysis was completed, ready for the upcoming license round. A Labrador Sea sampling survey (LBS14) was acquired in 2014 to help identify and characterize the petroleum system(s) in the offshore Labrador basins. A basin geohistory model was developed and calibrated with vitrinite reflectance and temperature data for a number of wells on the shelf. A number of pseudowells in the basin were modelled. Thermal modelling was used to determine the optimum reservoir and source rock zone and the risk on hydrocarbon charge. Oil shows in a well on the shelf in the vicinity of the NL01-LS sector demonstrates a lacustrine source (Bjarni Fm). The results from the sea floor samples taken over this sector identified zones of liquid hydrocarbon seepage with primary and secondary hydrocarbon signatures associated with Type II/III (marine/marine delta). The marine sediments of the Markland (K80-K60) and Cartwright (T40) formations on the slope and basin floor are buried to sufficient depths to be within the oil window, with expulsion during the Late Eocene to Oligocene. This study identified a significant Mass Transport Complex (MTC) on the Labrador slope which would have been deposited prior to and during expulsion. A number of structures associated with this MTC have been identified and would likely have been in place at the time of expulsion allowing for the trapping of hydrocarbons.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016