WHALE

OFFSHORE NEWFOUNDLAND: SOUTH WHALE BASIN SOURCE ROCK STUDY

WHALE LOCATION MAPClick on the arrows below for an outline and contents of the study.

Please contact Dr Jonathan Bujak for further details

BACKGROUND

The study was undertaken jointly by Bujak Research and David Mudge Associates to determine the petroleum source rock potential of the Whale Basin on the southern Grand Banks of Newfoundland.

Palaeoceanography, basin configuration and the deposition of phytoplankton in the North Atlantic region predict the  distribution of Oxfordian-Kimmeridgian oil source rocks across the region and support kerogen types present in the southern Grand Banks wells and oil-bearing sections in northeast Newfoundland and the North Sea

OUTLINE OF THE STUDY

Upper Jurassic shales are generally considered to be the primary source for oil discoveries in the Grand Banks area of offshore eastern Canada. Biostratigraphic analysis indicates that these rocks are of Oxfordian to early Kimmeridgian age, coeval with the primary oil source in northeast Atlantic basins including the North Sea, Faeroe-Shetland and Porcupine basins. The Grand Banks of Newfoundland are underlain by a number of Mesozoic basins with hydrocarbon potential. These include the South Whale, Whale, Horseshoe and Jeanne d’Arc basins. The drilling of more than 70 wells has resulted in 15 significant oil discoveries, all located in the Jeanne d’Arc Basin. No hydrocarbon discoveries have been made in the Whale or Horseshoe basins, where much of the Upper Jurassic-Lower Cretaceous section is missing due to early Cretaceous (Avalon) uplift and erosion.

However, the South Whale Basin was located southwest of the axis of maximum uplift, and a more complete Upper Jurassic-Lower Cretaceous section has been preserved. n this basin, oil was discovered in Upper Cretaceous Petrel limestone in Heron H-73, with 22 bbl of 7-11.5°API oil being recovered on test. A small gas discovery has also been made in Tors Cove D-52, located in the cap rock (Iroquois Formation) of a salt diapir. All but one of the 13 wells drilled so far in the South Whale Basin have been located over salt diapirs, volcanic or basement highs, encountering incomplete Upper Jurassic-Lower Cretaceous sections with only limited data collected on prospective source rock and reservoir intervals.

Although the number of oil discoveries outside the Jeanne d’Arc Basin has been very small, previous stratigraphic and kerogen analysis has highlighted the presence of potential oil-prone source rocks in the Upper Jurassic section of the South Whale, Whale and Horseshoe Basin wells (BMIC, various studies). In contrast, similar studies of Upper Jurassic rocks from Scotian Shelf wells do not appear to include a significant source for liquid hydrocarbons due to the predominance of gas-prone organic material. This ‘herbaceous-woody’ kerogen is quite different to the ‘amorphous sapropelic’ kerogen that characterises oil-prone source rocks.

OBJECTIVES

The principal objective of this study therefore was to investigate the source rock potential of Upper Jurassic rocks in the South Whale Basin area. This work has been carried out in three phases:

  1. Stratigraphic interpretation of the Jurassic-Cretaceous section in a suite of wells from the South Whale and Whale basins, calibrated with data from selected wells in the Horseshoe and Jeanne d’Arc basins, and the Scotian Shelf.
  2. Paleoenvironmental interpretation of these well data to identify paleoceanographic and other geologic events in the stratigraphic record.
  3. Production of a suite of paleogeographic and paleoceanographic maps for a series of late Jurassic and early Cretaceous time slices.

CONTENTS


  1. INTRODUCTION
  1. MESOZOIC STRATIGRAPHIC ANALYSIS

2.1       Introduction

2.2       Biostratigraphic scheme

2.3       Stratigraphic surfaces

2.4       Stratigraphic sequences

  1. UPPER JURASSIC PALEOENVIRONMENTAL ANALYSIS

3.1       Introduction

3.2       Classification of kerogen types

3.3       Origin of source rock facies

3.4       Stratigraphic distribution of source rock facies

3.5       Geographic distribution of source rock facies

3.6       Paleoceanography and source rock potential

REFERENCES

TABLES

1.1       Well database

2.1       Jurassic-Cretaceous microfossil bioevents

APPENDICES

APPENDIX 1: Interpreted well stratigraphy and paleoenvironmental charts

APPENDIX 2: Abbreviations for key Mesozoic marker species

APPENDIX 3: Mesozoic palynological zonation

APPENDIX 4: Biochemical and thermochemical fluorescence

FIGURES

  1. Introduction

1.1       Well location and bathymetry

1.2       Tectonic elements, South Whale and Whale basins

1.3       Depth to continental basement, Scotian Shelf-Grand Banks

1.4       Mesozoic stratigraphic framework, Scotian Shelf-Grand Banks

  1. Mesozoic stratigraphic analysis

2.1a     North Atlantic palynological zonation

2.1b     North Atlantic planktonic foraminiferal and calpionellid zonation

2.1c     North Atlantic calcareous benthic foraminiferal zonation

2.1d     North Atlantic arenaceous benthic foraminiferal zonation

2.1e     North Atlantic ostracode zonation

2.2       Middle Jurassic-Upper Cretaceous stratigraphy, South Whale and Whale basins

2.3       Well correlation, South Whale Basin

2.4       Well correlation, Whale Basin

2.5       Well correlation, South Whale and Whale basin

2.6       Middle Jurassic-Upper Cretaceous unconformities, South Whale and Whale basins

  1. Upper Jurassic paleoenvironmental analysis

3.1       Correlation of Jurassic-Cretaceous kerogen ratios, Scotian Shelf and Grand Banks wells

3.2       Plot of amorphous sapropel, Scotian Shelf to Jeanne d’Arc Basin

3.3       Stratigraphic distribution of Middle Jurassic-Upper Cretaceous paleoenvironments, Scotian Shelf to Jeanne d’Arc Basin

3.4       Offshore eastern Canada Callovian/Oxfordian paleogeography (160 Ma)

3.5       Offshore eastern Canada Oxfordian/Kimmeridgian paleogeography (154 Ma)

3.6       Offshore eastern Canada Portlandian paleogeography (148 Ma)

3.7       Offshore eastern Canada Valanginian paleogeography (135 Ma)

3.8       Late Jurassic global oceanic systems

3.9       Late Jurassic-early Cretaceous oceanic model

3.10     North Atlantic Callovian/Oxfordian paleoceanography (160 Ma)

3.11     North Atlantic Oxfordian/Kimmeridgian paleoceanography (154 Ma)

3.12     North Atlantic Portlandian paleoceanography (148 Ma)

3.13     North Atlantic Valanginian paleoceanography (135 Ma)

WELLS

Stratigraphic charts, including bioevents, logs, sequence, lithology and kerogen, and tables of sequence and bioevent tops are provided for the following wells:

Bittern M-62

Carey J-34

Cook K-56

Demascota

Eider M-75

Emerillon C-56

Gannet O-54

Heron H-73

Hibernia B-08

Kittiwake P-11

Mallard M-45

Merganser I-60

Mic Mac H-86

Narwhal F-98

Panther P-52

Pelican J-49

Puffin B-90

Razorbill F-54

South Venture O-59

Tern A-68

Terra Nova K-08

Tors Cove D-52

EXAMPLE FIGURES

WHALE Fig 308Whale Figure 3.8 Late Jurassic global oceanic systems

 

 

 

 

WHALE Fig 309Whale Figure 3.9 Late Jurassic-early Cretaceous oceanic model

 

 

 

 

WHALE Fig 310Whale Figure 3.10 North Atlantic Callovian/Oxfordian paleoceanography (160Ma)

 

 

 

WHALE Fig 311Whale Figure 3.11 North Atlantic Oxfordian/Kimmeridgian paleoceanography (154 Ma)

 

 

 

WHALE Fig 312Whale Figure 3.12 North Atlantic Portlandian paleoceanography (148 Ma)

 

 

 

WHALE Fig 313Whale Figure 3.13 North Atlantic Valanginian paleoceanography (135 Ma)

 

 

 

 

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