Miocene carbonates are present in the northeast part of the Kerchen Peninsula, which is the easternmost part of the Crimean Peninsula. This region is characterized by open and closed elongate anticlines, in the cores of which are Miocene clays. Diapirs and mud volcanoes occur here.
Miocene Chokrak sediments 30-80 m thick rest uncon- formably on Maykop clays. The Chokrak here consists of detrital shell limestone, sandstone, and conglomerate. Some reefs are also present. Above this are the Miocene Karagan Beds, which consist of organo-clastic limestone in the lower part followed by uniform clays.
Detailed study of the Semenov, Aktash, Voykov, Borzov, and Priozer closed productive anticlines has shown them to be similar. The Semenov structure is an elongate feature cut by a fault, which has a displacement of 130 m. Angle of dip on the northwest block is 12-13 degrees to the north, and on the southeast block it is 30 degrees to the south.
Commercial oil has been found in two horizons of the Chokrak and in three of the Karagan. These are separated by clay dividers 2-5 m thick, which isolate them hydrodynamically. The uppermost pools in the Semenov and Aktash fields have gas caps. An oil pool and a gas pool separated by a 0.6 m thick clay bed are present in the Barzov field.
Reservoir properties in the fields of the study area are good. The carbonate rocks are thicker at the crests of each fold. Porosity is high due to leaching cavities. Good permeability accounts for high recovery. Reservoir properties are less favorable on the flanks of the structures.
The oil from these carbonate sediments is heavy and is low in paraffin, tar, and sulfur. The gas/oil ratio ranges from 4 to 30 cubic meters per cubic meter. The gas is 75-86 percent methane.
Similar fields may be found on closed structures in the north and east of the Kerchen Peninsula.
Taken from Les'kin, 1986; digested in Petroleum
geology, Vol. 23, No. 9/10, two maps and two cross
sections.
Copyright 2003 James Clarke. You are encouraged to print out
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