The expected growth in oil prices in 2018 will positively affect the implementation of the Eurasia project, just as any other exploration project, Kazakh national oil and gas company KazMunaiGas told Azernews.
The implementation of this project will be carried out in accordance with the agreed terms, commercial conditions and in line with the current legislation, the company noted.
The estimated term of the work performance is estimated to take 6-7 years, according to KazMunaiGas.
Azerbaijan’s state oil company SOCAR, along with KMG Eurasia LLP, Agip Caspian Sea B.V., RN-Exploration LLC, CNPC International Ltd., and NEOS GeoSolutions, signed a memorandum of understanding (MoU) on implementation of the Eurasia project, which envisages development of the Caspian Depression in Kazakhstan on June 21, 2017.
Talks will be held on key commercial, technical and contract conditions of the Eurasia project for signing a contract for geological exploration of the Caspian Depression in line with the legislation of Kazakhstan.
SOCAR representatives are taking part in all meetings of the working groups, KazMunaiGas company’s representative stressed.
It was highlighted that all decisions on the issues related to Eurasia project are being taken unanimously with all potential participants of the project.
The volume of investments will be specified after negotiations, the company added.
Prospects of oil and gas content of sedimentary basins on the territory of Kazakhstan and, in particular, the Caspian Depression, are of great interest to the state and large international oil companies, KazMunaiGas underlined.
The Caspian Depression is a low-lying flatland region encompassing the northern part of the Caspian Sea, the largest enclosed body of water on Earth. Probable reserves in the Caspian Depression are estimated at 60 billion tons of oil. The project is expected to provide the oil and gas industry of Kazakhstan with a stable source, letting avoid the decline in production, which may occur in 15-20 years, and it will also become the foundation of the country's energy security.
The main purpose of the Eurasia project is to study the deep geological structure of the Caspian region with the aim of discovering new and large hydrocarbon deposits and establishing the regularity of their distribution at great depths.
Global oil production is likely to decrease in 15-25 years due to depleted reserves by that time. Kazakhstan’s giant oil fields - Tengiz and Kashagan - are among those fields that are predicted to see reduced output after 2040.
Therefore, new oil deposits need to be found and in this regards the perspectives of the Eurasia project cannot be overestimated.
The North Caspian depression is largely onshore north of the Caspian Sea. It extends oven an area greater than 500,000 sq km. The section is divided by thick Lower Permian Kungurian salt into sub-salt and supra-salt parts (Gabrielyants and others, 1990, Regional Geology of oil-gas regions of USSR, in Russian).
Although geophysical study of the North Caspian depression has extended over several decades, there has been a paucity of information on the deep subsurface of its central part, where depth to the top of the salt is 10-12 km. The sub-salt section had been depicted as dipping gently and smoothly toward the central part of the depression. Common depth point seismic surveys in recent years, however, have disclosed quite a different picture. The sub-salt section is divided into a pre-platform mega-complex, which is pre-Late Devonian, and overlying platform mega-complex, which is Late Devonian to Early Permian in age. The structure on the tops of both these complexes turns out to be very complex - a sag complicated by faults, highs, and downwarps.
The Sarpin downwarp in the southwest part of the North Caspian depression extends some 250 km in a northeast direction and is 100 km wide. To its northeast is the Aralsor basement high, and then farther to the east in the central part of the depression is the Kushum arch. Eleven well-defined highs have been mapped on the top of the sub-salt section on the Kushum arch and other parts of the depression.
What is the petroleum potential of these rocks? Upper Devonian source beds such as the Domanik and older bituminous carbonates and shales are certainly present in the section. Clastic and carbonate reservoirs are available, and seals are regional. But would the oil be over-cooked? Maybe not. The thick salt is a good conductor and will have drained off much heat, thereby permitting liquid oil to survive at greater depths. But even if oil has not survived the high temperatures at depth, gas and gas condensate can be present in great amounts. Perhaps there is a herd of elephants down there.
The North Caspian oil-gas province is located on the southeastern margin of the East European craton. It extends over an area of more than 500,000 sq km. The Lower Permian Kungurian salt complex of this depression consists largely of salt but also contains lenses of anhydrite, clastics, and carbonate. Original thickness is estimated at 2-3 km; however,it has flowed plastically into some 1200 salt structures. This salt is theseal for pools in the underlying section and is the main factor for trapping hydrocarbons in the section above the salt (Gabrielyants and others, 1991). During the last two decades new types of salt-related traps have been described, thereby broadening prospects for oil and gas. Bedded salt conformable with the enclosing rocks is found in the border areas of the depression. Thickness there ranges fr om tens of meters to 200-300 m, and anhydrite is common. Height of salt domes ranges fr om 500-1000 m on the borders of the depression to 8-9 km in the central part. The North Caspian depression has practically no solitary domes. On the whole they combine into salt ridges or merge into single gigantic domes. Three types of domes are recognized: non-piercing, crypto-piercing, and piercing. The non-piercing domes have caused weak deformation of the overlying Triassic rocks. The Triassic-Cenozoic section is preserved above these domes. The crypto-piercing domes penetrate to various stratigraphic levels of the Mesozoic. The Triassic is absent in places with Jurassic resting on the salt. Crests of piercing domes typically subcrop beneath the Neogene cover or penetrate to the surface. Traps associated with these salt domes are classified as supra-dome, peripheral, flank, sub-cornice, and infra-dome. The supra-dome structures are those associated with the upper surface of the dome fr om its highest part to the boundary wh ere the flank plunges into inter-domal space. The peripheral features are highs located along the margins of a dome above a steep flank but still above the top of the dome. In spite of limited reserves, peripheral traps qualify as supplemental targets in fields wh ere the main production is from other types of traps. Two classes of structure occur on the flanks of domes: traps beneath tongues of salt that extend out from the dome (cornices) and beds that abut up dip against the salt. The infra-dome traps are in reservoir rock that is included between salt beds of different age. In the border areas of the depression wh ere the salt occurs as a blanket, the salt beds and overlying sediments level out the relief on the sub-salt complex, thereby creating traps. Such traps are common in the southern part of the depression. Traps related to faults along the border of the depression are small and have low closures. Non-piercing domes in the border areas of the depression form anticlines that range in size from 2 by 1 km to 6 by 3 km. They are host to pools with significant reserves; however, their number is small. Such traps are probably present offshore on a continuation of the Prorva arch. The piercing domes on the whole have broad crests with no well expressed outline - "spilling out" toward the periphery of the dome. Unconformities are commonly associated with these features. Other traps are associated with salt ridges that connect salt domes
The shelf of the north part of the Caspian Sea is a continuation of the onshore North Caspian Lowland. Water depths are less than 5 m in 70 percent of this offshore area. This shelf area is a zone of junction of the East European craton and the Scythian and Turan platforms.
The Carboniferous upper Visean - lower Bashkirian carbonate complex consists of organic and organo-clastic limestone. Its lithologic composition is persistent regionally. On the paleo-shelf of the North Caspian depression it consists of massive reservoirs of the pinnacle reef (Tengiz) and carbonate platform (Astrakhan and Primore) type.
The upper Visean - lower Bashkirian Astrakhan carbonate massif is located in the northwest paleo-shelf part of the North Caspian. Thickness of these carbonates is up to 2 km. The reservoir rock is biomorphic and organo-clastic limestone. Resting on an erosion surface at the top of the Bashkirian are deep-water Asselian - Artinskian clayey limestones and shales. These are the seal for a massive hydrocarbon pool. Sequence seismic stratigraphy shows presence of local reef bodies along the east perifery of this massif.
In the northeast coastal area of the Caspian Sea are the Primore carbonate platform and the Tengiz pinnacle reef. The Primore massif measures 60 by 20 km - almost half offshore. Biothermal limestones consist of algal, coral, foraminifera material, and organic detritus. Reef deposits are widespread in the Tournaisian-Bashkirian part of the section. These are overlain discordantly by Artinskian carbonate-clay deposits. The Tengiz reef massif (all onshore) is composed of Serpukhovian limestones and occupies an area of 400 sq km. Thickness of the carbonates of the Primore and Tengiz features is more than 1 km.
The offshore Shaburbali carbonate massif is west of Tengiz and southeast of Atarau. It was disclosed by gravity surveys and outlined by seismic surveys.In the structurally highest part of the massif at depth of 3.8-4.0 km are individual crests, which combine into the northeast-trending Shaburbali arch. This feature is 80 km long, 20 km wide, and has closure of 2 km on the surface beneath the Permian Kungurian salt.
The Kerogly massif is west of Shaburbali massif and directly south of Atarau. It consists of a 2-km thickness of Carboniferous-Upper Devonian carbonate rocks that occur as a series of isolated biohermal buildups. On the flanks these pass into deep-water facies.
The Zhambay carbonate massif extends far offshore from the vicinity of Astrakhan. It is a clearly expressed structure of biohermal-erosional origin. Kungurian salt is either not present here or is thin and flat-lying.
By analogy with adjacent onshore areas the Zhambay, Kerogly, Shaburbali, and other offshore structures are assessed as highly favorable for discovery of oil and gas.
Linear downwarps of the south border of the North Caspian depression are regarded as rift structures, which in late Hercynian time were subjected to inversion as a consequence of approach and collision of micro-plates.
By Kamila Aliyeva for AzerNews, James Clarke for Internet Geology.
