№ 4,
2008
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Geological-geophysical peculiarities of coral reef constructions of Mesozoic period (by example of ultradeep Saatly well SG-1)
1 – Institute of Geology and Geophysics of Azerbaijan National Academy of Sciences, AZ1143, Baku, H.Javid av., 119
2 – Geofizika Research Institute of State Oil Company of Azerbaijan Republic, Az1012, Baku, Moskow av., 73
Summary
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This paper focuses on seismogeological peculiarities of section of Saatly ultradeep well SG-1, nature of seismic waves registration on borehole, sizes and forms of anomalous bodies and there is some new information obtained by geophysical materials interpreted by present day methodics. For example, calcic series (H=2830-3500m) has been studied in details. It contains organogenic material, coral reef constructions and their influence on seismic wave fields.
The third group of waves takes the Middle Jurassic volcagenic series (H=3500-8314 m). here form of seismic registrations differs significantly from the first and second groups of waves. Here wave situation worsens and is of chaotic nature.
In horizontal and vertical directions velocities of waves spreading were defined on the base of field seismic materials, seismic and acoustic logging and reinterpretation of registrations of reflected waves record sections.
Velocity of seismic waves spreading increases by depth, as a whole. In the upper part of section stratal velocity of waves distribution (Var) is 2000-2100 m/s. In Sarmatian deposits it was 2,5 m/s. In deep part of well section in volcanogenic deposits values of stratal velocities are up to 6000 m/s. In depths interval H=2830-3100 m where deposits contain reef constructions, velocity of waves spreading reduces a little (by 100-150 m/s).
Change of other geophysical parameters of section can be found in carbonaceous deposits: such as results of electric, gamma-, neutron-gamma logging, etc. On background of gravitational maximum some decreasing of force of power (0,05 mg) can be observed. All anomalous phenomena are accompanied by velocity decrease of seismic waves spreading. Such changes occur in different parts of profiles passing through UD-1 towards NE-SW. So, geological-geophysical model of UD-1 area reflects all peculiarities of reef constructions of Saatly field.