Structural Study of the on/offshore Cantabrian Basin,
Northern Spain
Client:
Independent
oil company
Location:
Cantabria, Northern Spain and the near offshore.
Terrain and Climate:
Eastern and Central regions - undulating cultivated land.
Western region - Mountainous - Asturian Massif.
Area - km2:
Onshore TM coverage: 72,000 sq.km.
Offshore gravity interpretation: Bay of Biscay 160,000 sq.km.
Objectives:
Regional;
To assess the evolution of the Cantabrian Basin
in relation to the Hercynian and Pyrenean compression
events, and the intervening period of Atlantic extension.
Identification of regional structures missing on
the 1:200,000 scale geological map sheets.
Detailed;
Identification of throughgoing strike-slip faults
and their effect upon the subsequent compartmentalisation
of the Cretaceous basins and possible inverted basins.
Location of diapiric structures in transtensional
regions.
Extrapolation of onshore structures into the offshore,
and their integration with structures identified on
Seasat gravity.
Geology and Prospectivity:
Highly complex structural evolution
in a Carboniferous to Recent stratigraphic section.
Main plays occur in Aptian/Albian units
(extensional basins and associated rollover anticlines)
and are also associated with diapiric structures.
Basin structure is complicated by widespread
inversion.
Plays are also associated with Pyrenean
thrust related structures, ie. in the evolution of fault
propagation folds and fault bend folds.
Data available for integration:
Regional;
Incomplete Geological
maps at 1:200,000 scale.
Detailed;
Local seismic lines.
NPA study on Hydrocarbon Prospectivity of Northern
Spain.
Methods and Products:
Offshore ERS, Seasat and Geosat gravity ( 5mGal interval)
2 Landsat TM scenes digitally mosaiced and four sheets
extracted to conform with the published 1:200,000 scale
geological maps.
A 1:500,000 scale digital colour mosaic.
A 1:500,000 offshore Bouguer gravity map was computed
from Seasat and Geosat altimetry.
All of the above were presented with full colour clear
film interpretation overlays.
Benefits and Results:
An understanding of the regional geology and applying
this to structures identified on the local scale
Classification and grading of prospective (hydrocarbon)
plays based upon extensional, compression and diapiric associations.
Integration of several data sets enabling the near offshore
geology and structure to be understood.
Innovation:
Striking correlation found between onshore interpretation
and offshore gravity pattern, enabling qualitative interpretation
of the latter.
Successful integration of data from various satellite
gravity missions into a Bouguer map reproducible at scales
compatible with Landsat TM interpretation.
