The Dnieper-Pripyat gas-oil province has an area of 100,000 sq km
and a volume of sedimentary fill of 800,000 cu km. It is an aulacogen
that extends some 1200 km east-west and is 75 to 130 km wide. It
consists of two parts: the Pripyat downwarp on the west and the
Dnieper-Donets depression on the east. The Lower Carboniferous of
the latter is discussed here.
As of 1984 some 475 hydrocarbon pools had been found in the
Lower Carboniferous of the Dnieper-Donets depression; these are in
103 fields. The Lower Carboniferous of this depression is divided into
two plays: Tournaisian-lower Visean and upper Visean-Serpukhovian.
The first of these is in the transgrssive part of the Early Carboniferous cycle, and the second is in the regressive part. Separating these two
plays are clayey-carbonate rocks 100-500 m thick, which form a seal.
These were deposited at the time of maximum Early Carboniferous
transgression, when the sea extended far beyond the limits of the
Dnieper-Donets depression.
Seventy-three oil and gas pools in 39 areas have been discovered
beneath this Visean seal. In the Tournaisian sediments are 26 pools in
21 areas. Among these are 13 gas, 8 oil-gas, and 5 oil pools. Reservoirs
are sandstone-siltstone deposits.
Forty-seven pools have been discovered in lower Visean rocks in 33
areas. These include 26 gas pools, 9 oil-gas pools, and 12 oil pools.
The main pay is Horizon V-26, which is the basal Visean. These
pools occur in both structural and stratigraphic traps.
The upper Visean-Serpukhovian play is sealed by Serpukhovian clays
and Bashkirian carbonate-clay deposits. A total of 390 pools have been
discovered in this play in the Dnieper-Donets depression. This includes
193 gas pools, 98 oil-gas pools, and 99 oil pools. Most of these are in
the upper part of the Visean. It is interesting that the percentage of
pools that are oil does not decrease downward in the section. Also
of interest is the presence of pools in this part of the section beyond
the borders of the graben to the north just east of Khar'kov.
The Tournaisian is highly favorable for new discovery in all the middle
part of the Dnieper-Donets graben as well as the eastern half of the south
border zone, where several fields have already been discovered. The
lower Visean seal is good in these areas. In the western part of this zone
the Tournaisian is thinner, and the seal is not as good. Favorability of
the lower Visean is similar to that of the Tournaisian.
Areas highly favorable for the upper Visean include a large part of the
depression as well as an area outside the depression on the north. Areas
to the northwest toward Chernigov and along the southern border are
rated as only favorable. Favorability for the Serpukhovian is about the
same as that for the upper Visean. (Taken from Galabuda and others,
1984; digested in Petroleum Geology, vol. 25, no, 1/2, three maps.)
Numerous smaller transgressive-regressive cycles within the larger
Early Carboniferous cycle are attributed to sea-level changes occasioned
by glacial activity in the Southern Hemisphere at that time.
Copyright 2000 James Clarke. You are encouraged to print out this
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