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Integration
of Soil
Gas
Geochemical and Remotely Sensed Surface Lineament Data for
Oil
and
Gas
Exploration in the Western Canada Sedimentary Basin
By
Lynden A. Penner, M.Sc., P.Eng. P.Geo. ([email protected])
J.D. Mollard and Associates Limited, Regina, SK
Integration
of remotely sensed lineament and soil
gas
geochemical data with subsurface
geological and geophysical datatasets has proven useful for searching out
tectonically inherited subsurface structures and associated prospective
oil
and
gas
targets at several locations in southern Saskatchewan and Alberta.
Remotely
sensed images show lineament patterns and diagnostic geomorphic features at
regional and local scales throughout the Western Canada Sedimentary Basin. The
lineaments are often clustered along two or more dominant azimuthal trends,
forming distinctive patterns resembling regional joint patterns in sedimentary
rock. These distinctive surface trends and patterns appear to be genetically
related to subsurface structural elements that have been observed over a number
of
oil
and
gas
fields.
Contoured
and color enhanced soil
gas
data maps suggest patterns of hydrocarbon seepage
along preferred migration pathways, particularly over and around
oil
and
gas
reservoirs.
Gas
samples are analyzed for trace concentrations of methane,
ethane, propane, butane, hydrogen and helium. Diagnostic
gas
ratios that
characterize areas of anomalous
gas
seepage are used to predict compositions of
source reservoirs. Such data are thought to yield direct evidence of
hydrocarbons in the subsurface, even though in places
gas
constituent
concentrations in near-surface samples can be affected by multiple
gas
source
mixing and differential
gas
migration mechanisms.
Structural
elements that can contribute to identified soil
gas
anomalies and surface
lineaments include regional systematic fracture patterns, reactivated fault
movement associated with regional tectonism, fracture-controlled salt
dissolution with associated differential subsidence effects, differential
crustal rebound associated with preglacial erosion and deglaciation, and
paleoerosion and paleodepositional patterns influenced by underlying structure.
Several
case history examples illustrate the different types of data correlated, the
techniques used, and study results. They include
oil
and shallow-
gas
pool areas
in western Saskatchewan and southeastern Alberta. Integration of remotely sensed
lineament and soil
gas
geochemical data is currently being applied at the
Weyburn
oil
pool in southeastern Saskatchewan to help assess the integrity of a
Mississippian carbonate reservoir subjected to CO2
injection for enhanced
oil
recovery.
