AAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Investigations of the Basement Fractured Zones in the Volga-Ural Region
(1) Department of Geology of Oil and Gas, Kazan State University, Kazan, Russian Federation.
(2) Department of Geology of Oil and Gas, Kazan State University, Kazan, Russian Federation.
(3) Department of Geology of Oil and Gas, Kazan State University, Kazan, Russian Federation.
(4) Department of Geophysic, Kazan State University, Kazan, Russian Federation.
Geological structure of the Russian plate, including the territory of the Tatarstan Republic, and oil and gas presence in the sedimentary cover of this region permit a conclusion that the Precambrian crystalline basement (CB) can be considered as a potential target for hydrocarbon exploration. CB in Tatarstan has been studied by deep drilling to a depth of several hundred metres to 4 km and by up-to-date geophysical and geochemical techniques.
The extensive basement drilling has permitted the discovery of numerous loosely aggregated and fractured zones of varying volume capacity and fluid content. The basement reservoirs vary in thickness from several metres to several tens of metres. These have been found both in the uppermost portion of the basement and at a depth of more than 5 km. The basement reservoirs have been identified by various geophysical techniques. More than 130 loosely aggregated and fractured intervals of the basement have been tested using the drill stem tester, compressor and deep-well pumps.
Geophysical and geological investigations have indicated numerous reservoir zones in CB bearing the traces of bitumen and fluids enriched with the dissolved hydrocarbon gases. What are those seismic heterogeneities of the Earth’s crust that have been identified by the regional seismic studies? What stages of tectonic activity (past or recent) do they reflect? How true is the concept that the roots of the ancient, stable formations are still active and bear the marks of the long-term metamorphic dehydration permitting the long-term existence of fluid-bearing zones in the Earth’s crust? What is the relationship between the geophysical heterogeneities of the crust, its fluidisation, and the tectonic development regime within individual structures of the ancient platforms characterised by geophysical anomalies and neotectonic activities? To what extent do the present-day mantle processes going on under the thick craton crust affect its strata? Do they take place in the sedimentary cover, and what are their mechanisms and forms? How do these processes affect the formation of mineral deposits including oil and gas fields? All these issues appeared in recent years and are directly related not only to fundamental studies but also to practical problems associated with the petroleum exploration.