Increasing geological efficiency of gravimagnetic research for local structures and evaluation of their oil-and-gas content in Kura depression
Gadirov Vagif Gadir oglu
Efficiency upgrade of gravimagnetic research for oil-and-gas content structures and direction of preliminary drillings to O&G in intermountain Kura depression are the objectives of the thesis.
Petrophysical characteristics of eruptive rocks, cumulative geological section of depression, variations of density, magnetic susceptibility, temperature vertical and lateral were analyzed. Methods for field operations, processing and interpretation materials, isolation of local anomalies aligned with local uplifts and oil-and-gas content were offered to increase geological efficiency of gravimagnetic research.
Complex of gravimagnetic researches for the purpose of direct prospecting oil-and-gas reservoir searches in different geological conditions of Azerbaijan were proved, physico-geological basis of imaging of local uplifts and oil-and-gas reservoirs in gravity and geomagnetical field were studied.
Physical parameter modifications of eruptive rocks in geological section leading to anomalous variations of gravity and geomagnetic field over oil-and-gas fields were analyzed. Availability of sub-vertical zone over oil-and-gas reservoir was shown and given quantitative estimate of physical parameters of this zone on basis of actual data.
Relative density, magnetic susceptibility decreases and temperature increases in same horizons over oil-and-gas reservoir on Middle Kura depression, were observed.
Imaging of structural-tectonic features of Mesozoic complex on gravimagnetic fields were proved through mathematical and natural models. Correlations between occurrence depth of Mesozoic complex and Bouguer anomalies were developed and polynomial dependencies were concluded. Mesozoic surface depth was calculated and two and three dimensional contour maps were built by this surface for different oil and gas field Middle Kura depression based on formulas and gravimetric data. On generalized allocation map of local structure for SE part of YevlakhAghjabadi depression at 11th tectonic zone, on NW-SE direction were found more than 80 local structures, lots of which escaped the detection by geophysical surveys before. Structures in Productive Series were expressed by local maximum of gravity field in Lower Kura depression.
By analyzing actual data (seismic and gravimetric) was found that nonanticlinal traps (at nip zones) installed by seismic materials on gravity field imaging with sudden changes of horizontal gravity gradient.
New estimated oil-and-gas reservoirs over Panahly-Orujlu, Naftalannorth Naftalan-Duzdagh, Gazanbulag-Borsunlu-Ziyadkhan, ArabkubalyAkhtachy, Bandovan, Navahi, Goytepe and etc; Middle- and Lower Kura depression areas were forecasted on basis of gravimagnetic trap type anomalies. These anomalies were compared with seismic trap type anomalies for more reliability. Sufficient correspondence of gravity and seismic anomalies conditioned by oil-and-gas reservoirs was observed. Recommendations were given for search-post holes work and complex geophysical (seismic-gravic-magnetic) researches for revised geological model and oil and gas reservoirs of fields.
Fundamental results of theoretical and empirical researches achieved in intermountain Kura depression were brought out in conclusion.