Dr. Theses

Seismicity of the South Caspian depression

Yetirmishli Gurban J.

The South Caspian depression (SCD) is considered one of regions with high seismic activity. In the past here took place the set of destructive earthquakes, eruptions of mud volcanoes, and geodynamic and seismotectonic processes were tracked by anomalistic geophysical variations. These processes have played the important role in a geological structure of lithosphere, an origin and migration of a hydrocarbon, and also in forming of fields in patterns with favorable conditions. And now abrupt change of a geodynamical-tension and increase of seismic activity in various time intervals is observed.

Gathering of macroseismic and tool data, their ordering and the analysis, learning by modern methods of seismicity of oil and gas areas of Azerbaijan, eliciting of laws of connection of seismicity and oil-and-gas content is one of actual problems of modern geology and geophysics.

Widening of building recently in republic, speed-up of operation of oil and gas fields and accumulation of power resources in large terminals, realization of projects on supply of safe transportation of oil and gas on the world markets on export pipe lines creates necessity for carrying out of seismological researches by means of modern devices and interpretation of the received data at high scientific level with application of the newest methods of researches. Until recently learning of the geologic environment of the produced region and the analysis of seismological data were executed by means of traditional methods at which one application existential variations of the geodynamical – tension state of environment on the basis of geophysical regime observations were not allowed and results were mostly grounded on macroseismic and tool data.

The analysis of seismological data received by means of a new digital seismotelemetering complex “KINIMETRICS” taking into account results of geophysical monitoring demonstrates, that not the account of the anomalistic variations which are originating in the environment in due course, at seismic risk zoning in many cases augments probability of occurrence of ecological danger in region.

The work purpose – investigation of a seismotectonic situation of the South Caspian depression on the basis of new data, spatial-temporal variations of geophysical fields for the purpose of revealing of laws of correlation of an oil-and-gas content and seismicity.

Scientific novelty held by the author research consists in identification of seismodangerous zones of oil-and-gas areas of the South Caspian depression and compiling of a map-scheme of possible maximum magnitudes of earthquakes, in an establishment of zones of the geodynamic intensity, dedicated with anomalistic seismic activity. In the South Caspian depression seismotectonic features potential zones of earthquake hypocenters, and also variation of well production rate on oil and gas fields during the periods of seismic activity before and after earthquakes are revealed. It is erected, that growth of geodynamic intensity and seismic activity in SCD result to activization of activity of mud volcanoes, to growth of quantity of eruptions. On the basis of the analysis of new complex geophysical and seismological researches the high potential of a deposit of hydrocarbons on depths of 8-12 km is established.

The analysis of data accumulated on each field once again demonstrates that during the periods of activization of earthquakes and the mud volcanoes which have been laied out on fields extraction from oil-wells varies. Observation of such factors testifies to characteristic variations on fields caused by seismic activity and emphasizes importance of learning of such laws.