Browsing by Author "Aydemir, Attila"

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3-D Gravity Modeling of the Kars Basin as a Hidden Extension of the Caspian Petroleum System, Ne-Anatolia, Turkey
(Springer Basel Ag, 2024) Aydemir, Attila; Bilim, Funda
The Kars Basin in northeastern Turkey is closely related to the Caspian Petroleum System but it is hidden by a great extent of volcanic rocks. The Oligo-Miocene Komurlu Formation within the basin is the Turkish equivalent of the Maikopian Formation which is the main source rock in the Caspian region. Although the Kars Basin has considerable hydrocarbon potential it is one of the least explored basins in Turkey and there is only a limited literature on the region. This study is the first comprehensive investigation to determine the basement geometry, depth, internal structure and basin boundaries. Gravity data and power spectrum analysis were used in this study. The gravity anomalies were low-pass filtered and the average depth of the basin is found to be approximately 5 km. Boundaries of the basin are entirely confined within the Turkish territorial borders. The basin geometry is remarkably consistent with the crustal thickness geometry across the region and the maximum crustal thickness is 42 km, indicating that the basin was formed on the thickest part of the crust in the region. A 3-D model of the Kars Plateau indicates that the Kars Basin is made up of four different deep (> 6 km) depressions forming a channel-like trend from southwest to northeast from the Horasan area to the Arpacay area. There are four less deep sections (< 6 km) to the north of this trend. The depressions in the north are separated by the Allahuekber Mountains that are marked by a distinctive magnetic anomaly, from the deep SW-NE trend. High-standing regions between the depressions could be prospective areas for the oil accumulation.
Citation - WoS: 13
Citation - Scopus: 13
Crustal Thickness in the Black Sea and Surrounding Region, Estimated From the Gravity Data
(Elsevier Sci Ltd, 2021) Bilim, Funda; Aydemir, Attila; Ates, Abdullah; Dolmaz, M. Nuri; Kosaroglu, Sinan; Erbek, Ezgi
In this research, the crustal thickness (Moho depth) variations in the Black Sea and surrounding region were calculated from the regional gravity anomaly data using an empirical equation. The data were obtained from the open source of Bureau Gravimetrique International (BGI) in digitized form. The gravity anomaly values are changing from 80 mGal in the onshore Black Sea region in Turkey to 260 mGal in the deeper parts of the sea. Maximum gravity anomaly indicates a consistent pattern in the offshore Black Sea and anomaly pattern follows the shape of the shoreline. The pattern is consistent with the deeper parts in the marine area and the eastern anomaly extends into the Russian territory between NW of Georgia and SE of the Crimean Peninsula. The crustal thickness map indicates almost the same trends. In this map, the minimum crustal thickness is about 10 km around the mid of the Shatsky Ridge, close to the coastal regions of SE Russia and the second thinnest (12 km) place is located around the Western Black Sea Basin. The maximum thicknesses are represented with the 34-36 km contours in the onshore Eastern Black Sea region and east of Anatolia. On the other hand, the maximum crustal thickness to the north can reach up to 28 km around the Sea of Azov and to the east. The thickness variations are generally related with the main tectonic trends in this region. The Analytic Signal (AS) and maxima points of the horizontal gradients (maxspots) maps constructed from the gravity anomalies are also prepared in this research to see if these anomaly trends follow the tectonic lines. The regions of maximum and minimum crustal thicknesses are well-consistent with the AS anomalies and boundaries of the bifocal thin crustal sections coinciding with the Eastern and Western Black Sea basinal parts are surrounded with the maxspots. The northern thick crustal region around the southern margin of the Indolo-Kuban Basin is also surrounded by the maxspots. It is possible to claim that the maxspots map from the horizontal gradient of Bouguer anomalies reflects the boundaries of the main tectonic units in the Black Sea Region. Particularly, southern boundary of the Scythian Platform, southern boundary of the Shatsky Ridge and Great Caucasus thrust are distinctive and easy to follow in the maxspots map.
Citation - WoS: 2
Geoengineering Properties of the Ertugrul (cayirkoy) District, Nilufer Province, Bursa-Turkey, by Using Geophysical Methods and Borehole Data
(Elsevier, 2020) Cetin, Fatma; Kutluk, Hatice; Aydemir, Attila
In this study, soil classification experiments and geophysical studies are carried out for the evaluation of local ground soil conditions by using the data and samples from the boreholes in the Quaternary sediments in the Ertugrul district of Nilufer, Bursa, then the engineering parameters and index classifications are also investigated with the soil mechanics experiments using the disturbed samples from the drill holes. The grade of swelling (bulking) potential in the ground soil is found medium, high and very high in different parts of the study area. The basement units for the constructions bear very low liquefaction risk. The plasticity index varies between 9 and 25, but active mass movements are not expected. However, engineering problems such as swelling (bulking), soil settlements, bearing capacity reduction may be expected under the seismic forces because of the alluvial composition, 0-5 degree soil inclinations and being located in the 1st degree earthquake hazard risk zone. Therefore, the study area may be classified in the 'precautionary zone' in the urbanization category in terms of engineering problems. (C) 2020 Elsevier B.V. All rights reserved.
Citation - WoS: 5
Citation - Scopus: 5
Geophysical Investigation of the Geothermal Potential Under the Largest Volcanic Cover in Anatolia: Kars Plateau, Ne Turkey
(Springer Basel Ag, 2020) Aydemir, Attila; Bilim, Funda; Avci, Birgul; Kosaroglu, Sinan
In this study, Curie-point depth (CPD), geothermal gradient, radiogenic heat production, and heat flow maps were constructed based on different thermal conductivity coefficients using magnetic anomaly data for the Kars Plateau, which has the largest volcanic cover in Turkey. The bottom depths of the magnetic crust in the research area were revealed by the CPD map for the first time in this investigation. There are two apparent magnetic anomaly trends in the study area: the first is the Horasan-Senkaya-Sarikamis-Selim-Arpacay trend in the NE-SW direction, and the other is the Hanak-Ardahan-Arpacay trend in the NW-SE direction. Two other prominent elongations extend into the Ardahan-Gole-Senkaya and Kars-Digor axes. All these trends represent mountain chains and/or stratovolcanoes in the region, and no anomalies are observed around the non-volcanic outcrops. Curie depths are shallow, up to 14 km between Horasan and Kagizman towns, and 12 km in the northwestern part of the study area. Gradient values can reach 50 degrees C km(-1) in the northwestern sector, together with the high heat flows represented by the 150 Wm(-1) K-1 contours. The deepest CPD region lies between Gole and Susuz towns, where the geothermal gradient decreases to 27 degrees C km(-1). Heat flows decrease 60 Wm(-1) K-1 in the same area. An apparent gap around the Kars Plateau was observed in previous regional heat flow maps of Turkey by other authors (who used the bottom hole temperatures of boreholes and hot springs temperatures). This gap has been accurately filled from the results of this study, and geothermal exploration areas and the geothermal potential of the Kars Plateau have thus been determined for future exploration activity on the basis of the tectonic elements and earthquake data.
Citation - WoS: 6
Citation - Scopus: 5
Geothermal Prospectivity of the Bigadic Basin and Surrounding Area, Nw Anatolia, Turkey, by the Spectral Analysis of Magnetic Data
(Springer Basel Ag, 2021) Bilim, Funda; Aydemir, Attila; Ates, Abdullah
The Curie Point Depths (CPDs) are estimated from the spectral analysis of magnetic data in order to determine the geothermal potential of the Bigadic Basin and its surrounding region in NW Anatolia, Turkey. The estimated CPD range is from 7 to 17-18 km. The shallowest depth (7 km) lies to the north of Balikesir. The estimated geothermal gradient and heat flow values range from 33 to 80 degrees C/km, and 83 to 200 mWm(-2), respectively. All results in the study area support the previous studies from the geological or geophysical investigations for western Anatolia by other researchers. High temperatures may be resulted indirectly from the continental collision and consequent thermal relaxation and/or heating from the interiors of the Earth due to the mantle delamination or asthenospheric upwelling in response to lithospheric extension in the western Anatolia. The high heat flow and shallow CPDs can also be associated with the magmatic rocks as a consequence of the recent tectonic extension and granitoids in the studied region.
Geothermal Prospectivity of the Bigadic Basin and Surrounding Area, Nw Anatolia, Turkey, by the Spectral Analysis of Magnetic Data (jun, 10.1007/S00024-021-02787-y, 2021)
(Springer Basel Ag, 2021) Bilim, Funda; Aydemir, Attila; Ates, Abdullah
[No Abstract Available]
Innovative 3d Modeling of an Old Oil Field for Sustainable Production: Case Study of Katin-Barbes Oil Field (kbof), Se Anatolia- Turkey
(Elsevier Sci Ltd, 2023) Ozer, Zafer; Kamaci, Zuheyr; Aydemir, Attila
The goal of this study is to establish a workflow for the re-interpretation of almost depleted fields targeting the long-term sustainable oil production; in particular, for the oil fields in Turkey and the neighboring Middle Eastern countries located on the fold and thrust belts of the Zagros Mountains. It also fills some of the gaps in our understanding of the northern part of the Arabian Platform by describing the seismic characteristics of the Cretaceous reservoirs that were deposited during the Aptian to Turonian. The Katin-Barbes oil field (KBOF) in SETurkey was used as a case study. In this area, 3D seismic data were used for structural interpretation and remodeling of Cretaceous carbonates sedimented in the complex tectonic region. The well logs from 55 wells in the field were used to create a compilation of formation tops and were used as reference points for two separate sets of 3-D seismic data, acquired in 1991 and 2017. The quality of seismic data was improved with interpretation filters. The structural model was obtained by using various qualifiers from the seismic cubes and seismic facies changes were identified by analyzing a number of seismic attributes. Therefore, seismic data and velocities from the borehole measurements were combined to form a velocity model in building a structural model. Seismic attributes and well logs were used to create a porosity model. Consequently, top and base of two reservoir units; the Derdere and Sabunsuyu Formations have been clarified and re-defined, and potential new well locations were identified. Depending on the results of this investigation, 9 new wells were drilled in the potential areas in the KBOF, recently. Except the last one drilled on the NE boundary of the northern block, all wells have been completed as the "oil producing wells" and top of the reservoir units were encountered at almost the same depths in our depth model. Therefore, results and proposed methods in this research are confirmed by the real, borehole data. This research will be an examplary study for the re-evaluation of older and/or almost depleted oil fields, either in Turkey or in the other Middle Eastern countries.
Citation - WoS: 11
Citation - Scopus: 11
Interpretation of Aeromagnetic Data for the Geothermal Properties in the Northwestern Part of Turkey
(Pergamon-elsevier Science Ltd, 2021) Bilim, Funda; Aydemir, Attila; Ates, Abdullah
The northwestern part of Turkey is a significant area for its location on the accretionary region of several micro-continents and blocks. Therefore, there are several suture zones and western segments of the "North Anatolian Fault Zone" are scattered in the study area. Due to trans-tensional stresses, there are several pull-apart basins and/or depressions within the fault zone in the study area. As a consequence, it is also possible to observe magmatic intrusions into the fault segments. All these events and magmatic emplacements in the tectonic framework provide significant magnetic anomalies throughout the region. In this study, geothermal potential of the region is investigated based on the spectral analysis of the magnetic data, together with the seismic velocity (VP) distribution in the area using the log-linear relationship between the seismic velocity and the radiogenic heat production. Although two regions are emerging in the Curie Point Depth (CPD) and geothermal gradient maps, only one anomalous area from Bursa to Tekirdag may be considered as a promising region for the further geothermal energy exploration in the heat-flow maps prepared according to two different thermal conductivity coefficients. Seismic velocities are also low in this anomalous region decreasing down to 6.40 km/s around the shoreline of Tekirdag. Heat-flow values are increasing up to 110 mW/m(2) in this particular area where the CPDs are around 14 km.
Citation - WoS: 2
Citation - Scopus: 3
Interpretation of Aeromagnetic Data of the Sivas Basin in the Central Eastern Turkey
(Tubitak Scientific & Technological Research Council Turkey, 2021) Bilim, Funda; Aydemir, Attila
The Sivas Basin is located in the eastern part of the central Anatolia. In this study, aeromagnetic data in the basin and surrounding area are processed and anomalies are interpreted to determine the approximate locations of the causative bodies and reveal their relationship with the tectonic trends. The sedimentary basin is surrounded by strong magnetic anomalies from the south, east, and northeast. The most apparent anomalies are observed in the E-NE of Zara, SW of Divrigi, and north of Kangal. These anomalies do not present significant directional change when they are reduced to the pole process. Causative bodies of the southern anomalies around Divrigi and Kangal extend from NE to SW and the northerly anomaly trend (to the north of Kangal) crosses the southern one (Divrigi trend) in the analytic signal map. These trends are well-defined by the maxima points of the horizontal derivatives and these maxspots generally follow the boundaries of anomalies in the tilt angle snap. The Kangal Fault controls the extensions of the Divrigi anomalies through the north and they are not observed in the area to the north of the fault. The Hafik Anomaly in the north of the study area is also differentiated from the anomaly group in the E-NE of Zara precisely, defining that they are created by 2 different causative bodies. Aeromagnetic characteristics of the ophiolites to the south indicate that they have different origin from the northern ophiolites group. Similarly, it is determined that the plutonic rocks in the south and north are also different origin emplacements, considering their aeromagnetic responses, mineral contents, and ore deposit possibilities.
Citation - WoS: 7
Citation - Scopus: 7
Optimum Designs for 2-D and 3-D Seismic Surveys Via Modeling and Reverse-Time Migration: Pierce Junction Salt Dome, Texas
(Springer, 2021) Coskun, Suleyman; Stewart, Robert R.; Baysal, Edip; Aydemir, Attila
Establishing effective seismic survey parameters in complex structural areas, such as salt domes, is of vital importance for accurate imaging. Shot and group intervals, maximum offset, recording time and profile length, to image the subsurface structures, are critical 2-D parameters. Geometry, aspect ratio of a recording patch and number of in-line and cross-lines are key additional parameters for 3-D seismic design. This study provides a workflow for determining optimal 2-D and 3-D seismic survey parameters as exemplified by a Texas salt dome case. The Pierce Junction oil field, in proximity to the salt dome, is located in Houston, Texas, and has been one of the most prolific hydrocarbon producers in the region. Engineered caverns in the salt dome itself are now used for fluid storage. Design parameters for the future seismic surveys are partially informed by previous seismic data shot over the structure (where the top of the salt is at about 290 m depth and overlying cap rock, 210 m). Existing 2-D seismic data, crossing the salt dome, are processed to extract the velocities of the salt, cap rock, and near-surface sediments. In the following step, 2-D and 3-D velocity models of the study area are constructed using legacy well data as well as gravity measurements which were acquired as part of this study. Synthetic shot gathers are next modeled with a finite difference method using the acoustic wave equation. To generate images of the constructed model, reverse time migration (RTM) is applied to the synthetic data. By assessing the coverage and continuity of the imaged salt boundaries using a variety of decimated input data sets, the optimal survey parameters are determined. In this case, 20 m group and 40 m shot interval, 3000 m maximum offset, and 8 km profile length with a 4 s recording time are found to be most favorable 2-D acquisition parameters. Using similar coverage and continuity criteria, group and shot intervals of a 3-D seismic survey are determined as 25 m and 50 m, respectively. The receiver and shot line intervals are chosen as 250 m in an orthogonal geometry with 33 in-lines and 33 cross-lines distributed in the 8 x 8 km(2) survey area. The aspect ratio of any patch with 13 in-lines and 13 cross-lines is accepted as 1:1. This forward modeling and migration procedure, using a range of decimated data sets, can inform decisions on the final field parameters.
Citation - WoS: 3
Citation - Scopus: 4
Seismic Attribute Assisted Analysis of the Interpretational Variations in the Time and Depth Migrated Datasets: an Example From Taranaki Basin, New Zealand
(Elsevier Sci Ltd, 2023) Alyaz, Ahmet Murat; Bedle, Heather; Aydemir, Attila
In the regions with complex geology together with the apparent stratigraphic and seismic sequence events, time migration algorithms do not provide high-quality imaging for seismic interpretation due to strong lateral velocity contrasts, usage of average velocities in the vertical and horizontal directions, and without defining the ray -bending at interfaces. Therefore, the depth migration method using interval velocities and bended ray-traces at interfaces, provides more accurate results. There are also interpretational differences between the time and depth-migrated seismic data. The objective of this research is to compare these differences using several seismic attributes. In this context, we used the Toro 3-D pre-stack time and pre-stack depth migrated datasets from the Taranaki Basin, offshore New Zealand, because the Giant Foresets Formation presents suitable examples for the different types of channels like distributary, sinuous and meandering channels. Comparisons indicate that dip angles of the faults increased, channel walls become steeper and indicate more curvature, and structures get narrower in the depth-migrated data. There are also amplitude and phase variations in and around the channels. Most of the seismic data in the world are in the time domain and there is no sufficient borehole and velocity data. This situation may affect the attribute calculations in both migration data sets. The main goal of this investigation is to provide an understanding about the possible seismic differences in the time and depth migrations, the reasons behind them and, relationship between the lithology and probable seismic responses by using geomet-rical and physical attributes used in the seismic industry. These steps allow an accurate interpretation and more reliable evaluation of the subsurface structures. This study will also provide a toolkit and guidance for the in-terpreters in the time and depth migrations.
SWEEP SİNYALİ PARAMETRE SEÇİMİNDE ÖNERİLEN TEST ATIŞLARI, FARKLI KAYAÇ TÜRLERİ ÜZERİNDE YAPILAN BİR UYGULAMANIN PERSPEKTİFİNDEN VİBROSİSMİK PARAMETRELERİ İÇİN BİR METODOLOJİ
(2024) Karakaş, Türker; Aydemir, Attila; Aydemir, Attila; Bilim, Funda
Hidrokarbon aramacılığında en çok kullanılan yöntem, sismik yansıma yöntemidir. Bu yöntemde kaynak seçimi oldukça önemlidir. Sismik ekipler tarafından dünyaca en çok tercih edilen kaynak türü ise kontrollü bir kaynak oluşu nedeniyle vibratör olmuştur. Vibratörün yere gönderdiği sinyal “sweep sinyali” olarak adlandırılmaktadır. Bu sinyalin özellikleri, kullanıcı tarafından yeraltındaki tabakaların özelliklerine göre farklı bir parametre ile tanımlanır. Her saha, aynı jeolojik özelliklere sahip olmayacağı için parametre seçimleri de yüzeyin topoğrafik koşulları, yer içinin jeolojik şartları, sinyalin sönümlenme ya da yayılma durumu, hedef derinliğe ulaşması gibi birçok faktöre bağlı olacaktır. Bu nedenle sweep sinyalinin parametre seçimi için yürütülmesi gereken saha test çalışmaları veri toplama aşamasından önce yapılmalıdır. Bu çalışmada, hidrokarbon aranması için vibrosismik yöntem kullanılarak seçilebilecek bütün parametreler irdelenmiş, her bir parametrenin alabileceği değerler ve bunların etkileri tartışılmış olup Güneydoğu Anadolu’da seçilen bir çalışma sahasında örnek bir sweep test parametre çalışmasında en uygun kaynak parametreleri tespit edilmiştir. Böylece, yüzeyde bulunan, özellikle de sismik kalite için bozucu litolojilere sahip formasyonlar üzerinde seçilen parametrelerin gösterdiği farklılıklar ortaya konularak nedenleri tartışılmıştır. Bu çalışmanın önemi, sweep test çalışmalarında dikkate alınması gereken parametreler ve bunların hangi tip litolojilerde, ne gibi sonuçlar verdiğinin gösterilmesi açısından sismik endüstrisinde görev alacak jeofizikçilere referans teşkil etmesi şeklinde açıklanabilir.