Batı Siverek bölgesinin sismik yansıma ve araştırma kuyusu verileri ile tektonik yapısı ve petrol potansiyelinin değerlendirilmesi = Estimating of the tectonic structure and petroleum potantial of the western Siverek's region with seismic reflection and research well data

Abstract

Dünya enerji kaynakları içerisinde en önemli yeri şüphesiz fosil kökenli petrol ve doğal gaz oluşturmaktadır. Hidrokarbonun enerji anlamında bu derece öneme sahip olmasına karşın, ne yazık ki ülkemizde sadece Güneydoğu Anadolu ile Trakya Bölgelerinin bir kısmında bulunduğu bilinmektedir. Güneydoğu Anadolu Bölgesi'nde özellikle Doğu Fırat, Siverek ilçesi yakınlarında ve Batı Fırat petrol arama bölgesinde yer alan Piyanko, Yalankoz, Tokaris, Beşikli, D.Beşikli, Çaylarbaşı, Elbeyi, Bakacak ve Eskitaş üretim sahaları, bu havzaların hidrokarbon aramaları yönünden önemini artırmıştır. Doğu Fırat petrol arama sahasında yer alan ve daha önce açılmış olan Ü-1A, BS-1 ve D-1 kuyularında tespit edilen Mardin Grubu karbonatları ile Karaboğaz Formasyonunda test edilen petrolün, Yalankoz, Çaylarbaşı ve benzeri yeni petrol sahalarında da kapanlanabileceği düşünülmektedir. Bu çalışmada, Yalankoz, Çaylarbaşı ve civarının petrol potansiyelinin tespit edilerek yeni üretim sahalarının keşfedilmesi amaçlanmaktadır. Bu amaçla, çalışma alanımızı oluşturan Batı-Siverek bölgesinde yapılan Sismik yansıma çalışmalarından elde edilen sismik kesitler ve kuyu verileri kullanılarak bölgenin yapısal ve sedimantolojik trendleri tespit edilmeye çalışılmıştır. Batı-Siverek bölgesi, graben-horst tektonik yapısına sahip olduğundan çok sayıda faylar tarafından kuşatılmıştır. Sismik kesitlerde ve açılan sondajlardan alınan log korelasyonlarında ana fayların görülmesi, havzadaki petrol sisteminin (rezervuar, kaynak ve örtü kayalar) çok iyi çalıştığını ispatlamaktadır. Sismik kesitlerin yorumlarından ve önceden açılmış kuyulardan yararlanılarak bölgenin sismik hız haritaları elde edilmiştir. Ayrıca yorumlanmış sismik kesitlerden zaman haritası ve derinlik haritaları da hazırlanmıştır. En son olarak da derinlik haritasından yapı kontur haritası elde edilerek rezervuar olabilecek yeni alanlar belirlenmeye çalışılmıştır. Bazı kuyularda görülen hidrokarbon emarelerinin fay trendlerinde bulunan çatlaklardan geldiği gözlenmiştir. Sismik kesit ve kuyu verilerinin değerlendirilmesi sonucunda bölgede görülen hidrokarbon varlığının yerinde mi oluştuğu ya da göç ederek mi taşındığı hala tartışma konusudur. Yapılan bu çalışmayla, belirlenebilecek yeni rezervuar alanları ile petrolün bulunması ve türümün yerinde mi yoksa göç ile mi geldiği ve bölgenin petrol potansiyeli aydınlatılmaya çalışılmıştır. Ayrıca, çalışma alanında daha önce B-1, K.E-1, D-1, Ö-1, Ü-1A ve T-1 kuyuları açılmış ve bu kuyuların bir kısmında hidrokarbon varlığı tespit edilmiştir. Açılan bu kuyulardan elde edilen veriler ışığında ve bu çalışmanın sonuçları doğrultusunda yeni kuyuların (A1, A2 ve A3) açılmasına da karar verilmiştir.

The fossil-based petroleum and natural gas undoubtedly has the most important place among the world's energy resources. Despite the fact that Hydrocarbon has such great importance in terms of energy, it is known that it unfortunately is found in Southeast Anatolia and Thrace regions of our country. Piyanko, Yalankoz, Tokaris, Besikli, D. Besikli, Caylarbası, Elbeyi, Bakacak and Eskitas production areas which are located particularly in Eastern Fırat, Siverek district and in the western part of the Western Fırat exploration area in the South-Eastern Anatolia Region have increased the importance of this basin in terms of hydrocarbon searches. It is thought that Mardin group carbonates found in U-1A, B.S-1 and D-1 wells previously opened in South-Eastern Anatolia Region, located in Eastern Fırat petroleum exploration area, and the petroleum tested in Karabogaz Formation can also be closed in new petroleum fields such as Yalankoz, Caylarbası and the like. In this study, it is aimed to discover the new production fields by determining the petroleum potential of Yalankoz, Caylarbası and their surroundings. The Sadan Formation is the first sedimentary deposit of the Precambrian aged Telbesmi formation, which crops out around Mardin Derik and consists entirely of volcanic rocks, and is the first sediments of the Cambrian period. This unit and the subsequent succession present a regular sequence. Since it is known that the effects of the Hercynian Orogeny, which started in the Devonian and continued throughout the Carboniferous, continued in Southeastern Anatolia and caused epyrogenic movements, the Southeastern Anatolia basin was divided into three separate basins with the Mardin-Kahta uplift formed in this process and another uplift around Siirt-Sırnak. The west-southwest of the Mardin Rise is the Akcakale-Gaziantep Basin, and the east-northeast is the Diyarbakir Basin. The east of the Siirt-Sırnak uplift can be distinguished as the Hakkari basin. This thesis study The study area is located in the "graben area" between the E-1 and G-1 wells in the west of Siverek town. There are Piyanko-Yalankoz and B. Fırat fields to the west of this area, and E.Besikli and Caylarbası fields to the southwest. Since the study area is in the form of a graben area bounded by normal faults to the west and east, the oil-containing structures are within the graben area. Apart from these two large faults seen in the east and west of the region, some of the faults formed in the graben area are normal and some of them are reverse faults or thrust. The offsets of these faults are generally low and some of them limit the structures. The study area includes the eastern part of the Taurus orogenic belt, the marginal folds to the south of it and the autochthonous successions deposited along the northern margin of the Arabian continent further south. As seen from the surface geology map, both Cretaceous aged allochthonous units such as Kocali and Karadut, as well as xxiv Tertiary aged allochthonous units such as Cüngüs, Maden formations and Paleozoic metamorphics crop out in the northwest half of the study area due to severe Tertiary tectonics. The areas in front of the Tertiary thrusts were filled by the Selmo and Lice formations. The south of the study area is covered with widespread Karacadag basalts. The API of the oil found in previously drilled wells in the region is low-medium. In addition, it is seen that the API grading decreases in the north-east-southwest direction. This suggests that the oil discovered in the region was not an in formation but was transported by migration. During the studies, to make a general geological evaluation (structure, stratigraphy, extension, facies) for the location, to include the interpretations and approaches in terms of reservoir (pressure, porosity, permeability) and geochemistry with calculated or measured parameters. For this purpose, structural and sedimentological trends of the region were tried to be determined by using seismic sections and well data obtained from the seismic reflection studies in the West-Siverek region constituting our study area. West-Siverek region is surrounded by numerous faults since it has a graben-horst tectonic structure. The presence of main faults in seismic sections and log correlations from drilled wells proves that the petroleum system in the basin (reservoir, source and seal rocks) works very well. Seismic velocity maps of the zone have been obtained from interpretations of the seismic sections and using pre-opened wells. Time maps and depth maps are also prepared from interpreted seismic sections. Finally, attempts were made to identify new areas that may be reservoirs by obtaining a building contour map from the depth map. The seismic line density in the study area is quite high. In the SE-NW direction, the seismic grid is approximately 1.5 km. In the SW-NE direction, the seismic grid is approximately 2.0 km. Approximately 1000 km in 305 km2 working area. The 2D seismic line is interpreted. Most of the seismic lines are collected with vibrator energy source. However, there are also seismic lines collected with dynamite. Most of the seismic lines were collected and processed by TPAO. In case of exploration in the study area, a 3D seismic program is planned in the future to reveal the hydrocarbon potential of the region. When the check-shot and sonic records of the wells drilled in and around the study area were evaluated, the velocity value of the Mardin level was determined for each well. These operations were carried out in a total of 9 wells. Datum 700 was taken from the velocity data obtained throughout the field, and the average velocity map for the 1/50000 scaled karababa-c level of the study area was prepared. All these studies were carried out with Landmark DGS software. The velocity map of the A-1 well emerged from the velocity map created. These operations were carried out in the A-2 and A-3 wells. Then, shift removal was performed on all 2B seismic lines. These processes were done in Landmark DGS software. After removing the shifts, the levels of the şelmo, germav, sayindere, kastel, karababa-c and derdere formations were followed and interpreted in the Landmark DSG system for all sections. After all the comments were completed, the time map for the karababa-c level was prepared. From the speed and time maps obtained, depth was passed and a depth map was created. The equation x=v(m/s) * t(s) was used while going to the depth. Finally, the 700-depth equation was used to generate the building contour map. In addition, a structure-contour map was created. All these procedures were performed for the A-2 and A-3 wells. It was observed that hydrocarbons in some wells come from cracks in the fault trends. It is still a matter of debate whether the presence of hydrocarbons in the region observed as a result of seismic section and well data evaluation is formed on site or carried with migration. With this study, it was aimed to find petroleum with reservoir areas that can be identified, and whether the emanation occurred onsite or carried by immigration, and the petroleum potential of the region. In addition, B-1, K.E-1, D-1, O-1, U-1A and T-1 wells were opened in the study area and hydrocarbons were detected in some of these wells. It has also been decided to open the new wells of (A1, A2 and A3) in the light of the data obtained from these wells and in the direction of the results of this study. The following conclusions were reached in the studies carried out to determine the reasons for the lack of economic hydrocarbon potential in the wells drilled so far in the study area. No structural defect is observed. The structures in the drilled wells were tested and no structural defect was found. In the evaluation made in terms of facies, it was observed that the Mardin group facies in the West generally continue here as lithofacies. However, the porous packages seen in the above-mentioned areas, especially in the KBB-C member, were passed with both thinner thickness and lower porosity in the wells drilled here. On the other hand, permeabilities are also quite low. However, both porosity and permeability are sufficient in the Derdere formation. In some wells in the study area, the Karababa formation and the oil findings seen in the formations above it are not economical and have the character of limited developed reservoirs. In the pressure map, it is seen that the formation pressures in the study area are higher than the areas in the west. This may indicate that hydrocarbons may have migrated to the western areas. According to the results of the analyzes made for the maturity and generation of oil, there is no negativity in terms of hydrocarbon generation in the wells drilled in the graben area in the west. However, in the wells drilled in the eastern part of the graben, it was observed that the source rock potential was either at the limit or at a low level. Although economic oil is not found in previously drilled wells in the study area, testing of new structures in the region may be considered. Wells planned to be drilled; It is located in an area where oil is produced and discharged, near oil production areas and there is no source rock and cover problem in the study area. However, the structures in the region are Cretaceous structures. The seismic quality of the seismic lines interpreted to explore the oil potential of the study area is quite good. In addition, the oil presence in the region can be shown to be obtained as a result of the reentry operation, upon the presence of oil traces in the U-1/A and D-1 wells. There are porosity and permeability problems of reservoir levels (Karabogaz and Karababa-C) in previously drilled wells. However, although approaching the fault in the wells helps to increase the permeability, the wetness of the Derdere formation in the region poses a risk that these faults will carry the Derdere water up. Petroleum discovery has also been made in the licenses of some private companies within the study area. When we look at the study reports of these companies, the discoveries were generally obtained from the traps.According to the results of the A-1, A-2 and A-3 wells, which will be decided to be drilled as a result of this study, new work plans will be designed in the region and the information on the existence of the oil potential that the region has so far will be updated. As a result of the blending of the obtained data with the previous data, it will be on the agenda to go further south of the study area for oil exploration. In addition, the investigation of the oil potential at the Kastel level, which is located above the Mardin level, may be on the agenda in the study area at a later stage.