Seysmology and Earth physics

Numerous studies have proved the connection between low-amplitude local anomalies of gravity and magnetic field with oil and gas deposits in both platform and geosynclinal areas. In theoretical and experimental studies, gravity and magnetic prospecting methods for forecasting oil and gas accumulations in various geological structures have been used. They show out that oil and gas deposits located in different oil and gas regions of the world are noted discoveries with geophysical methods, including gravitational and magnetic fields. As a result, new exploration signs have identified the appearance of local gravitational and magnetic minima of various intensities above the productive parts of the structures. It has been established that the first physical and geological prerequisites for using gravimetry and magnetometry to explore hydrocarbon deposits in Azerbaijan are decreases in the density and magnetic susceptibility of rocks in the area of the deposit. Gravity-magnetic studies carried out in the Kura depression show that over the known deposits (Muradkhanly, Jafarly, Tarsdallar, Gazanbulag, Babazanan, Bandovan, etc.), gravitational and magnetic minima of 0.2-0.8 mGal and 20 -30 nT. the Physical and
geological properties of the Muradkhanli field have been modeled by studying some of the physical parameters in the Middle Kura depression of Azerbaijan (the changes in the magnetic susceptibility, temperature, and density of rocks in the subvertical zone above and below the reservoir). In this study, the results of gravimetric and magnetometric
studies performed for oil and gas deposits on the areas of Arabkubaly, Naftalan, Northern Naftalan, Gedakboz of Azerbaijan are presented. Consequently, the outcomes of experimental and systematic work carried out in the areas of Middle Kura Depression and Lower Kura Depression show the effectiveness of gravity-magnetic methods.

Abstract
Local gravity and magnetic anomalies are employed to identify potential hydrocarbon reservoirs in the Middle Kura Depression (MKD) within the South Caspian basin in Azerbaijan. The MKD basin in Azerbaijan including the Yevlakh-Agjabedi trough covers a large part of the Kura intermountain basin between the Greater and Lesser Caucasus. In the study region,
several local gravity and magnetic anomalies are discovered related to oil and gas deposits in the sedimentary depression whose thickness is 12–14 km. Gravity minima and maxima expressed by different wavelength anomalies are indicative of density variations within the basin. Local gravity minima with an intensity of 0.3–0.4 mGal identified in the study areas are related to the oil–gas deposits. While the local positive magnetic anomalies are associated with the volcanic formations,
local negative magnetic anomalies appear over the productive parts of the buried structure within the sedimentary complex. Intense local magnetic minima anomalies with an intensity of 20–30 nT are evidence of oil and gas accumulations. The limitations of traditional methods for interpreting gravity and magnetic data to locate oil and gas fields have led to the use of gravity field gradients. This alternative approach has proven advantageous, as it confirms the results of gravity exploration and is useful for directly searching for hydrocarbons.
Keywords Gravity · Magnetic · Gravity gradient · Local minimum · Local maximum · Azerbaijan

Аннотация. В статье рассматривается вопрос о распределении вулканогенных образований в геологических разрезах Среднекуринской впадины в связи с размещением в них скоплений углеводородов. Показаны возможности определения геометрической формы, глубины залегания и мощностей вулканогенных образований по данным грави-магниторазведки. Указано на возможности образования в регионе нетрадиционных вулканотектонических ловушек. Обосновывается наличие осадочного комплекса под вулканогенной толщей в Среднекуринской впадине, который может содержать скопления нефти и газа.
Ключевые слова: вулканотектонические ловушки, грави-магниторазведка, залежи нефти и газа.

Magnetic surveys are one of the most mobile and low-cost geophysical methods. However, direct searching of hydrocarbon deposits by the magnetic method was questioned for a long time because of the virtual absence of the magnetic properties of oil and gas. Last investigations indicate that physical-chemical reactions of hydrocarbon deposits with the host media often create precursors for detecting directly magnetic signals from the oil and gas deposits even in the cases of large depths. Extraction of low-signal magnetic anomalies generated by hydrocarbon deposits is demonstrated on examples of several deposits from the Middle Kur Depression (Azerbaijan) and Dnieper-Donets Depression (Ukraine). Application of the proposed magnetic data analysis will allow not only to optimize hydrocarbon deposit searching in complex geological environments but also to decrease the number of prospecting boreholes.

In the article describes the studies carried out on the direct forecasting of hydrocarbon deposits by RWM of seismic exploration, high-precision gravity and magnetic survey in the Uchtol-Kutarma area of the southern side of the Fergana depression. Within the area studied, a number of anomalies associated with the presence of oil and gas deposits were identified, exploration drilling was recommended. According to the results of exploratory drilling of well No.1 in Kutarma area, the identified anomalies were partially confirmed.

The modern gravimetric equipment allows to register very small effects of gravity field changes and can be applied solving different geological, geophysical and environmental problems. However, sometimes insufficient calculation of various kinds of geological noise complicates effective application of detailed gravity field analysis. One of such factors is the temperature regime over and outside different buried objects of investigation. In this paper temperature changes in a subvertical zone over a hydrocarbon deposit and outside its contour are analyzed. The integrated density change and corresponding gravity effects are calculated for the Muradkhanly oil deposit situated within the south-east part of the Middle Kura Depression (central Azerbaijan). Calculation of these effects on the basis of density- temperature data correlation analysis could significantly improve the microgravity field examination over the hydrocarbon deposits. The similar correction procedure may be applied a...

Local gravity and magnetic anomalies are employed to identify potential hydrocarbon reservoirs in the Middle Kura Depression (MKD) within the South Caspian basin in Azerbaijan. The MKD basin in Azerbaijan including the Yevlakh-Agjabedi trough covers a large part of the Kura intermountain basin between the Greater and Lesser Caucasus. In the study region, several local gravity and magnetic anomalies are discovered related to oil and gas deposits in the sedimentary depression whose thickness is 12–14 km. Gravity minima and maxima expressed by different wavelength anomalies are indicative of density variations within the basin. Local gravity minima with an intensity of 0.3–0.4 mGal identified in the study areas are related to the oil–gas deposits. While the local positive magnetic anomalies are associated with the volcanic formations, local negative magnetic anomalies appear over the productive parts of the buried structure within the sedimentary complex. Intense local magnetic minima anomalies with an intensity of 20–30 nT are evidence of oil and gas accumulations. The limitations of traditional methods for interpreting gravity and magnetic data to locate oil and gas fields have led to the use of gravity field gradients. This alternative approach has proven advantageous, as it confirms the results of gravity exploration and is useful for directly searching for hydrocarbons.

Monoqrafiya müəllifin 40 ildən artıq bir dövrdə, Azərbaycanın müxtəlif neftli-qazlı rayonlarında apardığı qravimetrik və maqnitometrik tədqiqatların nəticələrinə həsr olunmuşdur. Burada qravi-maqnit kəşfiyyatının Azərbaycan şəraitində tətbi-qinin fiziki-geoloji əsaslarına, aparılmış tədqiqatlardan alınmış geoloji nəticələrə və neft-qaz yataqlarının axtarışı və kəşfiyyatı istiqamətlərinə aid 3 hissə verilmişdir. Müəllif Azərbaycanın müxtəlif NQR-də lokal strukturların axtarışında və çökün-tülərin neftli-qazlılığının proqnozlaşdırılmasında qravi-maqnitometrik kəşfiyyatın tətbiqinin əhəmiyyətini göstərmiş, eksperimental və nəzəri tədqiqatları müqayisə edərək con nəticədə qravi-maqnitometrik kəşfiyyatla dərinlik geoloji quruluşun öyrənilməsinin, neft-qaz yataqlarının proqnozlaşdırılmasının mümkünlüyünü gös-tərmişdir.
Kitab qravi-maqnit kəşfiyyatı ilə məşğul olan mütəxəssislər, geofiziklər, geoloqlar,  tələbələr üçün faydalı mənbə ola bilər.