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Moesian Basin (Romania) - Exploration History Overview
Situated between the Southern Carpathians and the Danube, this basin
is little understood and much misunderstood, due to its reverse
tectonics and rather more illusive reservoirs (subtle traps, carbonates,
The post-war hydrocarbon discoveries of the 1950's and 1960's were
part of an intensive wildcat exploration programme: consequently
an exploration activity map of this region of some has 30,000 sq.
Kms. would give the impression of a high density of wells, which
may suggest that the basin had reached a mature stage of exploration.
Quite the contrary this first impression is highly misleading, as
the basin remains under explored a closer analysis of data would
point to a lack of meaningful geological control, for the following
a) early exploration wells were targeted solely on gravity and magnetic
surveys and not on seismics.
b) the 1950's drilling engineers often used heavy mud in order to
avoid blow-outs (inevitably missing the oil reservoirs) and were
paid on the drilled footage, rather than on the success ratio, therefore
the early wells would have to be reassessed in order to define the
basis and conditions in which they were drilled
c) the early seismic data of the 1960's and 1970's lacked transparency,
especially in the deeper section
d) all exploration was based on targeting conventional four-way
closures, of sand reservoirs, controlled by normal faults within
the shallow geological section, ignoring the existence of subtle
traps, carbonate reservoirs, reverse tectonics and reverse and strike-slip
faults. Hydrocarbon finds in subtle traps and carbonate reservoirs
were generally the result of chance wildcatting rather than of a
full understanding of the geology
e) some of the deeper wells with a TD in the Lower Tertiary and
Mesozoic section were located on shallow four-way closures, which,
in a reverse basin, had no meaningful structural control
As a general conclusion:
much remains to be done in order to define new plays.
As part of this reassessment of data in hand the Philosophy of the
montages included in this Study is to present the existing finds
in the context of the basin's Structural Geology and Stratigraphy
which should indicate the direction of future exploration.
In this context Celtic Petroleum has produced a four-volume study
including the Romanian and Bulgarian Moesian with two volumes of
text and two of plates, of which, the present volume contains a
set of 15 colour montages of the Romanian Moesian, @ 1:500,000 scale.