Print this pageOil resources of the third Ciężkowice sandstone in the Osobnica oilfield (Silesian Unit, Polish Outer Carpathians) - sedimentological characteristic
Pawel Lis, Polish
Geological Institute, Regional & Oil Geology Department,
Described petroleum reservoir is the
third Ciężkowice sandstone, composed of the
late Paleocene age channel fill and depositional lobe succession. Osobnica
field is a part of an ancient deepwater fan, referred to as the Eastern Fan.
Within this horizon the seven sandstone packages interbedded
with mudstone/fine sandstone deposits were recognized. The first three packages
are characterized by a coarsening-upward and thickening-upward sequence, which
are interpreted as depositional lobe sediments. The next four packages, roughly
40 m thick each, are characterized by a fining-upward and thinning-upward
sequence, which are interpreted as channel fill deposits. Because of the large
number of well data (156 well in the 1,6 km2
area) resources were calculated by volumetric method. For the purpose of
geological modelling Landmarc
co. ZMAPPlus software was used and the results were visualized with the ArcView program. In the Osobnica field the total resources
are calculated on 491500 tons, from which some 352600 tons of oil have been
exploited so fare. Map of the resources arrangement and the structural model
allowed to point out the main factors controlling
distribution of hydrocarbon resources in the Osobnica field. Among them the
most important is the shape of the structural trap. The less important is a facies arrangement. The main part of oilfield is in the SE
elevated part of the Osobnica anticline. Oil is accumulated in both channel- and lobe-type deposits. Among them, slightly more
predestinated for hydrocarbon accumulating is the channel fill sandstone.