--> Abstract: Revised Basin Configuration for the Labrador Offshore from Seismic and Gravity Data, Newfoundland and Labrador, CA, by James Carter; #90177 (2013)

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Revised Basin Configuration for the Labrador Offshore from Seismic and Gravity Data, Newfoundland and Labrador, CA

James Carter

Offshore hydrocarbon exploration along the Labrador margin has dominantly focused on the shelf, limiting the availability of data over deep water areas. In order to expand our knowledge of the exploration potential of the margin, long offset 2D seismic and gravity data (23,000 km over 2011-2012) was acquired by TGS, PGS and Nalcor Energy along the west-central area of the Labrador Sea. Covering the outer shelf, slope and deep water regions, a regional dataset now exists for areas that were never before imaged. Enhanced data quantity and quality have led to identification of extended Mesozoic and younger basin configurations. Critical to defining the extent and timing of these rift margin basins is mapping of the base syn-rift package. As part of the effort to delineate these new basin margins, gravity and seismic data interpretations were integrated to revise the top basement marker for the region. Basement along the Labrador margin varies between Paleozoic shelfal deposits and Precambrian crystalline rocks. Over the slope and deep water the basement gradationally varies from continental, to transitional, and finally into oceanic crust. Well ties from the shelf extend syn-rift Mesozoic-aged intervals into slope and deep water regions, and rift, drift and post-drift sediments are truncated against these aforementioned basement intervals. The majority of the rift section lies within rotated fault blocks bound by normal faults, and is of variable thickness. Improved seismic imaging at greater depths allows for mapping of the basement marker and defining the base of the rift sequence. Due to the variable nature of the basement and overlying strata, the character of the basement marker can change from fault block to fault block resulting in local confidence in the correlation of the horizon, but less confidence between faulted regions using seismic alone. Use of gravity data to refine the range of depth to basement has assisted in honing the interpretation and allowed for the regional thickness mapping of the rift package. By integrating these two data types, a revised basin configuration for the Labrador margin has been constructed, including definition of three new basins and the extension of a pre-existing one. Implications for petroleum exploration are twofold. Mapping of the syn-rift Mesozoic package from shelf to deep water extends the distribution of proven reservoir units encountered on the shelf into a larger syn-rift fairway that extends along most of the Eastern Canadian margin. Furthermore, interpretation of the regionally extensive base Tertiary marker, combined with the base syn-rift basement unconformity, allows for preservation over the majority of the project area of Late Cretaceous marine shales of the Markland Formation. Shales of the same age are known oil source rocks of West Greenland basins and this interpretation opens the possibility of a Late Cretaceous source rock fairway extending into the Labrador basins.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013