Thermal maturity, alginite-bitumen transformation, and hydrocarbon generation in Upper Ordovician source rocks, Saskatchewan, Canada

Journal Article · · Energy Sources; (United States)

DOI:https://doi.org/10.1080/00908319308909025· OSTI ID:6164551

Stasiuk, L D; Osadetz, K G ^[1]

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1. Inst. of Sedimentary and Petroleum Geology, Calgary, Alberta (Canada)

Organic petrological techniques have been used to study the alginite-bitumen-oil transformation in Upper Ordovician Yeoman Formation kukersite source rocks of the northern Williston Basin, Saskatchewan, Canada. The kukersites are characterized by two distinct interlaminated microfacies, disseminated and stromatolitic, each representing a growth stage of the precursor to the alginite maceral Gloeocapsomorpha prisca. Different rates of thermal maturation and thresholds of petroleum generation for the two G. prisca maceral subvarieties are indicated by different rates of percent reflectance in oil increase and are verified by shifts in fluorescence spectra and observations on transformation into bitumen. With increasing thermal maturation, disseminated G.prisca reaches a softening stage, losing its primary morphological features as it is transformed from a primary to a secondary maceral (bitumen). The stromatolitic subvariety of G. prisca does not display comparable alteration in response to increasing thermal stress. Hot stage experiments conducted on doubly polished thin sections of the kukersites support the optical discrepancies observed between the two maceral subvarieties in the subsurface. These findings indicate that hydrocarbon generation from kukersites may involve two steps controlled largely by organic microfacies. Inception of petroleum generation appears to occur at a depth of 3000 m for the disseminated alginite. Bitumen has been cracked to anisotropic 'coke' on a local thermal anomaly, and peak to postgeneration of petroleum has occurred at a maximum temperature of 148[degree]C, as suggested by homogenization temperatures for fluid inclusions.

• OSTI ID: 6164551
• Journal Information: Energy Sources; (United States), Journal Name: Energy Sources; (United States) Vol. 15:2; ISSN 0090-8312; ISSN EGYSAO
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200 -- Petroleum-- Reserves
Geology
& Exploration
04 OIL SHALES AND TAR SANDS
040200* -- Oil Shales & Tar Sands-- Reserves
Geology
& Exploration
040500 -- Oil Shales & Tar Sands-- Properties & Composition
BITUMENS
CANADA
CARBONIZATION
CHEMICAL REACTIONS
COKING
DATA
DECOMPOSITION
DEVELOPED COUNTRIES
ENERGY SOURCES
EXPERIMENTAL DATA
FLUORESCENCE
FOSSIL FUELS
FUELS
GEOLOGIC DEPOSITS
GEOLOGIC HISTORY
GEOLOGY
INFORMATION
LUMINESCENCE
MACERALS
MATURATION
MICROSCOPY
MINERAL RESOURCES
MINERALOGY
MINERALS
NORTH AMERICA
NUMERICAL DATA
OIL SHALE DEPOSITS
OPTICAL MICROSCOPY
OPTICAL PROPERTIES
ORGANIC COMPOUNDS
OTHER ORGANIC COMPOUNDS
PETROLEUM
PETROLEUM DEPOSITS
PETROLOGY
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
REFLECTIVITY
RESOURCES
SAMPLE PREPARATION
SASKATCHEWAN
SOURCE ROCKS
SURFACE PROPERTIES
TAR
WILLISTON BASIN