Ali Elmas

Lineaments in the Shamakhy–Gobustan and Absheron hydrocarbon containing areas using gravity data

In this study, we purposed to investigate the edge of geostructures and position of existing faults of the Shamakhy–Gobustan and Absheron hydrocarbon containing regions in Azerbaijan. For this purpose, the horizontal gradient, analytic signal, tilt angle, and hyperbolic of tilt angle methods were applied to the first vertical derivative of gravity data instead of Bouguer gravity data. We obtained the maps that show the previous lineaments which were designated by considering the maximum contours of horizontal gradient, analytic signal maps, and zero values of tilt angle, hyperbolic of tilt angle maps. The geometry of basement interface was also modeled utilizing the Parker–Oldenburg algorithm to understand the sediment thickness and coherency or incoherency between the gravity values and basement topography. The lineaments were held a candle to most current tectonic structure map of the study area. It was seen that the techniques used in this study are very effective to determine the old and new lineaments in the Shamakhy–Gobustan and Absheron regions. The epicenter distribution of earthquakes within the study area supports the new lineaments which are extracted by our interpretation. We concluded that better comprehension of Azerbaijan geostructures and its effect on the large scale works will be provided by means of this study.

A new method for determining lower density layer in prospection of hydrocarbon

Öz It is known that densities in formations are usually assumed to be constant for gravity model calculations. This also implies that formations are homogeneous and isotropic. However, the formations are usually heterogeneous and densities vary depending on heterogeneity. For this reason, densities should be taken into account as variables. Some scientists consider densities as variables in each formation in model calculations. In other words, density is defined as a function of the required parameters. In fact, functional change is regular. However, density is an irregular variable that depends on the change boundaries of seismic velocity. In this study, it is aimed to take density into account as a variable by using detected seismic velocity boundaries at which seismic velocity changes for each formation. In addition to main formations in model geometry in 3D inversion calculations, another formation was defined. This additional formation has been described by using a combination of all of the change boundaries of seismic velocity present in each formation in a specific order. The density calculated for the additional formation estimated the variation of density between the change boundaries of seismic velocity. This variation is added to the mass densities that are calculated for the description number of each zone. So, lower-density layer comprising oil can be determined by this method. The reliability of the results of the method depends on the reliability of seismic velocity boundaries. Moreover, the increasing number of seismic velocity boundaries leads to the increasing resolution of density variations. Bazı bilim adamları, 3 boyutlu gravite model hesaplamalarında, yoğunlukları her formasyon içinde değişken olarak ele alırlar. Yani yoğunluğu parametrelere bağlı bir fonksiyon olarak tanımlarlar. Bir yeraltı tabakası içindeki yoğunluk değişimi derinlikle orantılı olarak bulunur. Bu çalışmada, her formasyon içinde tespit edilen sismik hız sınırları kullanılarak, yoğunluğun değişken olarak göz önüne alınması amaçlanmıştır. Sismik hız sınırlarının izlediği yol, yoğunluk değişiminin bir göstergesidir. 3B ters çözüm hesaplarında model geometri içindeki ana formasyonlara ek olarak bir formasyon daha tanımlanmıştır. Bu ek formasyon tanımı, her formasyon içinde mevcut olan sismik hız sınırlarının tümü kesintisiz kullanılarak yapılmıştır. İşte bu ek formasyon için hesaplanan yoğunluk, sismik hız sınırları arasındaki yoğunluk değişim miktarı olarak kabul edilmiştir. Bu değişim, ana formasyonlar için hesaplanan yoğunluklara bir düzen içinde ilave edilerek, yoğunluğun derinlikle değişimi ayrıntılı olarak saptanmıştır. Bu çalışma, Adıyaman, Diyarbakır ve Gaziantep bölgesine ait sismik ve açılan kuyulara ait verilerin bir kısmının TPAO’dan alınmasıyla düşük hızlı yer altı modeli oluşturularak yapılmıştır. Bu çalışma sonunda sismik hız sınırlarının ekstra bir kütle olarak alınmasıyla yoğunluğun derinlikle nasıl değiştiği saptanmıştır. Böylece hidrokarbon içeren düşük yoğunluklu tabaka tespit edilmeye çalışılmıştır. Hidrokarbon aramalarında bu yöntem kullanılarak; daha az kuyu açılarak sonuca gidilebilir. Bu çalışmada, başlangıçta yoğunluklar sabit olarak dikkate alınmıştır. Fakat her tabaka içindeki yoğunluklar değişken olarak hesaplanmıştır.

Determining change of density with depth by using seismic velocity boundaries in 2D gravity inversion calculations

Densities in formations are usually assumed to be constant for gravity model calculations. This constancy implies that formations are homogeneous and isotropic. However, formations are usually heterogeneous, and densities vary depending on heterogeneity. For this reason, densities should be considered variables. Some scientists consider densities as variables in their model calculations of each formation. In other words, density is defined as a variable of the required parameters. In fact, variable change is regular, whereas density is an irregular variable that depends on the change boundaries of seismic velocity. This study aimed to take density into account as a variable by using determined seismic velocity boundaries at which the seismic velocity changes for each formation. The change boundaries of seismic velocity are an indication of the change of density in the formation. It is not possible for the respective description of this change to be variable for each point. In addition to defining the main formations in model geometry by using 2D inversion calculations, this study defined another formation, which is described with a combination of all of the change boundaries of seismic velocity that are present in each formation in a specific order. The reliability of the results of the method depends on the reliability of the seismic velocity boundaries. Moreover, an increasing number of seismic velocity boundaries lead to a higher resolution of density variations.

Determining change of density with depth by using seismic velocity boundaries in 3D gravity inversion calculations

Densities in formations (layers) are usually assumed to be constant for gravity model calculations. This constancy implies that formations are homogeneous and isotropic. However, formations are usually heterogeneous, and densities vary depending on heterogeneity. For this reason, density should be considered a variable, and certain scientists do just this in their model calculations for each formation. In other words, density is defined as a function of the required parameters. In fact, functional change is regular, whereas density is an irregular variable that depends on the changing boundaries of seismic velocity. This study aims to look at density as a variable by using determined seismic velocity boundaries at which the seismic velocity changes for each formation. The change boundaries of seismic velocity are an indication of the change of density in the formation. It is not possible for the respective description of this change to be functional for each point. In addition to defining the main formations in model geometries using 3D inversion calculations, this study defines another formation, which is described by a combination of all of the change boundaries of seismic velocity that are present in each formation in specific order. The reliability of the results of the method depend on the reliability of the seismic velocity boundaries. In addition, an increasing number of seismic velocity boundaries lead to a higher resolution of density variations.

Comparing of the 2D–3D Gravity Calculations in Cartesian Coordinates and 3D in Cartesian-spherical Coordinates

In this study, various calculations comparisons were made to achieve the best results in gravity computation. In the first study, 2D and 3D gravity computation were compared by using a suitable synthetic model in cartesian coordinates. And also in the second study, 3D gravity calculations are compared by using a suitable synthetic model in spherical and cartesian coordinates. In the first study, accuracy of the 3D gravity calculation results were found by inversion in cartesian coordinates. And also in the second study, the 3D gravity calculation results were found to be true in the spherical coordinates instead of in cartesian coordinates. The two studies, forward and inversion solutions were made for these model geometries by intensity of adoption by using a special algorithm (Cavsak H. 1992). Thus, the three-dimensional gravity studies are necessary to do is tried to explain in spherical coordinates.