Organic facies and maturation of Jurassic/Cretaceous rocks, and possible oil-source rock correlation based on pyrolysis of asphaltenes, Scotian Basin, Canada

Prasanta K. Mukhopadhyay, John A. Wade, Michael Kruge

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124 Citations (Scopus)

Abstract

This paper establishes source rock characterization and oil-oil and oil-source rock correlations of selected organic-rich shale source rocks and selected light oils and condensates from Jurassic and Cretaceous formations of the Scotian Basin. Multiple source rocks of Kerogen Types IIA (oil-prone), IIA-IIB (oil- and condensate-prone), IIB (condensate and gas prone), III (gas-prone), and IV (nonsource) are identified in various stratigraphic horizons. Vitrinite reflectance and Tinmax data indicate variable maturation histories, in different parts of the basin, which are related to differences in lithology-related heat conductivity and the presence of older sediments closer to areas of rifting. Multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families. Some Kerogen Type IIB rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions. A second family of oils could not be correlated with any of the analyzed source rock extracts. Pyrolysis-gas chromatography of asphaltenes from the Cohasset A-52 and Sable Island 3H-58 wells are significantly different in n-alkane, aromatics and phenol content. The asphaltene pyrolyzates of samples from Venture B-52 and S. Desbarres O-76 have a high aromatic content, low content of n-alkanes, and high phenol values (S. Desbarres), which is typical of a terrestial source. They correlate well with one another and also with Sable Island light oil. The N. Triumph G-43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons, with aromatic, phenolic and thiophenic compounds in low concentrations suggesting an algal source. Algal type organic matter may have made a contribution to the Cohasset petroleum, as its asphaltene pyrolyzate is also dominated by normal hydrocarbons.

Original languageEnglish
Pages (from-to)85-104
Number of pages20
JournalOrganic Geochemistry
Volume22
Issue number1
DOIs
StatePublished - 1 Jan 1995

Fingerprint

Asphaltenes
pyrolysis
source rock
maturation
Oils
Pyrolysis
Jurassic
Rocks
Cretaceous
oil
basin
rock
condensate
asphaltene
Kerogen
Aromatic Hydrocarbons
Alkanes
kerogen
Hydrocarbons
Phenol

Keywords

  • Canada
  • Rock-Eval pyrolysis
  • Scotian Basin
  • aromatic biomarkers
  • asphaltene pyrolyzate
  • condensate
  • kerogen type
  • maturation
  • organic facies

Cite this

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title = "Organic facies and maturation of Jurassic/Cretaceous rocks, and possible oil-source rock correlation based on pyrolysis of asphaltenes, Scotian Basin, Canada",
abstract = "This paper establishes source rock characterization and oil-oil and oil-source rock correlations of selected organic-rich shale source rocks and selected light oils and condensates from Jurassic and Cretaceous formations of the Scotian Basin. Multiple source rocks of Kerogen Types IIA (oil-prone), IIA-IIB (oil- and condensate-prone), IIB (condensate and gas prone), III (gas-prone), and IV (nonsource) are identified in various stratigraphic horizons. Vitrinite reflectance and Tinmax data indicate variable maturation histories, in different parts of the basin, which are related to differences in lithology-related heat conductivity and the presence of older sediments closer to areas of rifting. Multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families. Some Kerogen Type IIB rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions. A second family of oils could not be correlated with any of the analyzed source rock extracts. Pyrolysis-gas chromatography of asphaltenes from the Cohasset A-52 and Sable Island 3H-58 wells are significantly different in n-alkane, aromatics and phenol content. The asphaltene pyrolyzates of samples from Venture B-52 and S. Desbarres O-76 have a high aromatic content, low content of n-alkanes, and high phenol values (S. Desbarres), which is typical of a terrestial source. They correlate well with one another and also with Sable Island light oil. The N. Triumph G-43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons, with aromatic, phenolic and thiophenic compounds in low concentrations suggesting an algal source. Algal type organic matter may have made a contribution to the Cohasset petroleum, as its asphaltene pyrolyzate is also dominated by normal hydrocarbons.",
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Organic facies and maturation of Jurassic/Cretaceous rocks, and possible oil-source rock correlation based on pyrolysis of asphaltenes, Scotian Basin, Canada. / Mukhopadhyay, Prasanta K.; Wade, John A.; Kruge, Michael.

In: Organic Geochemistry, Vol. 22, No. 1, 01.01.1995, p. 85-104.

Research output: Contribution to journalArticleResearchpeer-review

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AB - This paper establishes source rock characterization and oil-oil and oil-source rock correlations of selected organic-rich shale source rocks and selected light oils and condensates from Jurassic and Cretaceous formations of the Scotian Basin. Multiple source rocks of Kerogen Types IIA (oil-prone), IIA-IIB (oil- and condensate-prone), IIB (condensate and gas prone), III (gas-prone), and IV (nonsource) are identified in various stratigraphic horizons. Vitrinite reflectance and Tinmax data indicate variable maturation histories, in different parts of the basin, which are related to differences in lithology-related heat conductivity and the presence of older sediments closer to areas of rifting. Multiple linear regression and cluster analyses of aromatic hydrocarbon ratios reveal two oil families. Some Kerogen Type IIB rock extracts match many of the light oil and condensates in terms of the aromatic hydrocarbon distributions. A second family of oils could not be correlated with any of the analyzed source rock extracts. Pyrolysis-gas chromatography of asphaltenes from the Cohasset A-52 and Sable Island 3H-58 wells are significantly different in n-alkane, aromatics and phenol content. The asphaltene pyrolyzates of samples from Venture B-52 and S. Desbarres O-76 have a high aromatic content, low content of n-alkanes, and high phenol values (S. Desbarres), which is typical of a terrestial source. They correlate well with one another and also with Sable Island light oil. The N. Triumph G-43 whole rock and extract asphaltene pyrolyzates are dominated by normal hydrocarbons, with aromatic, phenolic and thiophenic compounds in low concentrations suggesting an algal source. Algal type organic matter may have made a contribution to the Cohasset petroleum, as its asphaltene pyrolyzate is also dominated by normal hydrocarbons.

KW - Canada

KW - Rock-Eval pyrolysis

KW - Scotian Basin

KW - aromatic biomarkers

KW - asphaltene pyrolyzate

KW - condensate

KW - kerogen type

KW - maturation

KW - organic facies

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