Amir Kabir Semisubmersible Drilling Rig; Iran’s Asset in Caspian Sea
By Mahnaz Mohammadi
Amir Kabir semisubmersible drilling rig has got 8 anchors, weighing 20 tons each. A similar one exists only in the Gulf of Mexico. Amir Kabir drilling rig which is domestically manufactured is currently operating deep in Caspian Sea waters.
This drilling rig is exploring oil in Sardar-e-Jangal oil field in Caspian Sea. The rig is being operated thoroughly by Iranians, and it has so far drilled two exploration wells. The second well has just proven to contain oil.
An increase in Iran’s oil reserves and a boost in Iran’s bargaining power in international energy markets are among the results of Iran’s access to oil in the Caspian Sea. Based on positive results achieved from drilling exploration wells in Caspian Sea, exploration activities are expected to continue in the inland sea.
Here, exploration activities in deep waters of Caspian Sea are briefly reviewed.
Drilling at the depth of 3,500 meters in Caspian Sea resulted in the discovery of Sardar-e-Jangal oil field. The type of oil in this reservoir is light and of high quality. It would win many buyers. Sardar-e-Jangal is estimated to hold two billion barrels of oil with API 38. With a recovery rate of 25%, 500 million barrels of oil are recoverable from this field.
Following the discovery of the second oil well, these estimates are to change. Ali Osouli, managing director of Khazar Exploration and Production Company (KEPCO), has said that production from this field would be beyond estimates.
Oil recovery from Sardar-e-Jangal is much more different than extraction from other offshore fields because this field is located in Caspian Sea’s deep waters.
KEPCO is one of five upstream companies involved in exploration and production under National Iranian Oil Company (NIOC). KEPCO is tasked with exploration, development and production of oil and gas in the Caspian Sea and three northern provinces of Mazandaran, Guilan and Golestan. Monitoring the environmental issues related to oil and gas exploration and development in Caspian Sea are among other objectives of KEPCO.
Hydrocarbon in Caspian Sea
Caspian Sea is divided into three regions in terms of oil and gas reserves: Northern, Middle and Southern Caspian.
The Northern–Middle boundary is the Mangyshlak Threshold, which runs through Chechen Island and Cape Tiub-Karagan. The Middle–Southern boundary is the Apsheron Threshold, a sill of tectonic origin between the Eurasian continent and an oceanic remnant that runs through Zhiloi Island and Cape Kuuli. The Garabogazköl Bay is the saline eastern inlet of the Caspian, which is part of Turkmenistan and at times has been a lake in its own right due to the isthmus that cuts it off from the Caspian.
The Northern Caspian only includes the Caspian shelf, and is very shallow; it accounts for less than 1% of the total water volume with an average depth of only 5-6 meters (16–20 ft). The sea noticeably drops off towards the Middle Caspian, where the average depth is 190 meters (620 ft). The Southern Caspian is the deepest, with oceanic depths of over 1,000 meters (3,300 ft). The Middle and Southern Caspian account for 33% and 66% of the total water volume, respectively. The northern portion of the Caspian Sea typically freezes in the winter and in the coldest winters ice forms in the south, as well.
Based on the geologic reach of the Caspian basins, this report considers the North Caucasus oblast (province) to be the only part of Russia in the Caspian region. Although Iran abuts the Caspian Sea and is one of the Caspian's coastal countries, this report will focus mainly on offshore Iranian assets, since geologically the Caspian ends at the northern tip of Iran. Iran's main centers of oil and natural gas production are far removed from both the Caspian basins and the regional energy infrastructure network.
Extraction
A main characteristic of hydrocarbon reservoirs in the southern basin of Caspian Sea is related to changes in the hydrocarbon phase. Depending on the type of tectonic activities, quartz sedimentary series could be determining. Anywhere the quartz sediments are thick, there is naturally significant subsidence. In such zones, gas and condensate reservoirs take shape. In the zones with relative paleohigh in quaternary, oil reservoirs are formed.
Information about oil and natural gas reserves in Caspian Sea dates back to ancient times. From 600 BC to 12th century, Zoroastrians used to travel to Baku in Apsheron peninsula to worship a fire temple which burnt natural gas. There is evidence of oil having been a commercial commodity in the 10th century. Some reports say Baku used to export oil in the 13th century. In his travelogue, Venetian merchant traveler Marco Polo refers to an oil gush near Armenia.
The world’s first offshore wells and machine-drilled wells were made in Bibi-Heybat Bay, near Baku, Azerbaijan. In 1873, exploration and development of oil began in some of the largest fields known to exist in the world at that time on the Absheron peninsula near the villages of Balakhanli, Sabunchi, Ramana and Bibi Heybat.
By the turn of the 20th century, Baku was the center of international oil industry. In 1920, when the Bolsheviks captured Azerbaijan, all private property – including oil wells and factories – was confiscated. Afterwards, the republic's entire oil industry came under the control of the Soviet Union.
46 Structures in Southern Caspian
According to studies, Iran has identified more than 46 blocks in the Caspian waters, eight of which have been focused upon. Most of these structures are located 500 to 800 meters deep under water. Exploration drilling was done in these depths in order to complete exploration data.
Data gathering required some tools. For this purpose, construction of Amir Kabir oil rig as well as 16,000-horsepower Caspian-1, Caspian-2 and Caspian-3 vessels were considered. Despite all difficulties and restrictions, Iranian engineers managed to conduct drilling exploration operations in two years.
Some of activities conducted with regard to oil exploration in Caspian Sea are the construction of Amir Kabir oil rig, construction of multipurpose vessels, construction of logistics base for exploration, conducting operations to identify exploration blocks 6, 8 and 29 on 75 square kilometers in 2009, conducing AVO processing method in order to identify sandstone layer and assess its thickness and examine the existence of hydrocarbon in this layer, special processing to identify surface gas packages, oil exploration at the depth of 2,584 meters during the drilling of the first oil exploration well in Sardar-e-Jangal in 2012, conducing 2D seismic testing in Golestan province and revising studies conducted by South Caspian Study Group in order to study the volume of 28 out of 46 structures.
Exploration drilling has been conducted in Caspian Sea despite special conditions like the depth of water (700 to 1,100 meters), low visibility due to dust in the seabed, specific geological conditions, formation of mud volcano and high-pressure water streams.
Seismic Tests in Iran Sector
Between 1999 and 2000, KEPCO teamed up with a consortium of Shell, Lasmo and Veba Oil to study the Iranian sector of Caspian Sea. South Caspian Study Group (SCSG) was established to conduct the relevant studies. The main achievement of this study group was its finding about hydrocarbon in Iran’s sector.
An objective pursued by SCSG was to see if there was oil system in Iran’s sector of Caspian Sea. During 22 months, 2D seismic testing was conducted on 10,000 kilometers. SCSG also studied data related to 26 wells drilled by Azerbaijan and Turkmenistan in Caspian Sea and compared the formations in the wells of those countries with those in the wells drilled in Iran. Moreover, geochemical studies on oil leaks and consistency between these leaks and source rocks in neighboring countries were among other activities of this study group. Following geological and geophysical studies, 86 geological structures were explored in Caspian Sea, 46 of which were in better conditions. Eight were finally selected to undergo comprehensive study for exploration and production. To that effect, drilling operations were started on one of these eight blocks in February 2009. The result was the discovery of Sardar-e-Jangal reservoir.
Geological Hazards; Deepwater Drilling Challenges
The main challenge to geologists operating in the Iranian sector of the Caspian Sea is the non-existence of adjacent oil well or field for correlation.
In order to identify geological structures, formations or hydrocarbon reservoirs, the similarities between the wells being spudded and the wells drilled 500 meter to 2 kilometers farther are taken into account. The nearest field with useful data is Azerbaijan’s Shah Deniz which is nearly 170 kilometers away from Sardar-e-Jangal. That increases geological risks.
Since the sea environment is the main factor in designing marine structures, the Caspian Sea is being modeled by Iran-Astara oceanography mooring which is the only one in the Caspian waters.
This project was proposed by the Engineering and Manufacturing Directorate of KEPCO last year to provide highly valuable data. Meanwhile, due to the necessity of more precise meteorological data which the Meteorology Organization cannot provide, a second oceanography mooring is also planned to be purchased.
Another project was also introduced for supervising the steering of platforms and logistic vessels, managing maintenance and reparation of KEPCO fleet, safeguarding national assets and complying with international regulations.
KEPCO’s Planning and Project Control Section has drafted qualitative and quantitative objectives of the company’s 20-year following constructive interaction with different directorates.
The long-term plan defines objectives for KEPCO to realize from 2012 to 2032. The plan includes perspective, missions, macro objectives, key values, long-term, mid-term and short-term strategies and goals.
KEPCO’s Research and Technology Department approved a project for using advanced technologies in deepwater operations in order to manufacture equipment and revise measures of the past years.
This section was also pursuing a project for exploration, development and production studies in the Caspian Sea and three littoral provinces.
Another project is also under way to deal with possible crises and oil pollution leak. A roadmap has been devised for acquiring technology for deepwater exploration operations.
KEPCO Safety and Security System Implementation
In the meantime, a safety and security management project has been introduced in compliance with international obligations for the KEPCO fleet.
Other activities include location of land in the Caspian shores for development project. At the order of the Petroleum Ministry in 2004, studies were conducted on 300 ha of land in the northern city of Roudsar.
KEPCO’s Engineering and Manufacturing Directorate has completed the company’s drilling fleet by adding a relief and rescue vessel, two multi-purpose vessels, two pollution-removing vessels and a speed vessel.
Before taking the delivery of these vessels, comprehensive studies were conducted and options were examined. The vessels were purchased after the National Iranian Oil Company gave its nod.
Amir Kabir Rig Moved
After the drilling of the first well and the discovery of Sardar-e-Jangal in Caspian Sea, Amir Kabir oil rig was planned to be moved to a predetermined spot for discovery and acquisition of new hydrocarbon resources.
This operation was conducted by Iranian oil service workers with the help of Caspian-1 and Caspian-2 vessels. It was the first of kind in Caspian Sea’s deep waters. The whole operation lasted 36 working days.
Second Well Gushes Oil
After the end of drilling of the second exploration well in Sardar-e-Jangal at the depth of 3,500 meters, production tests were successfully conducted there and all exploration and appraisal objectives behind the drilling of the second well were realized.
Throughout these operations, data about pressure, temperature, amount of oil and the ratio of gas to oil as well as surface sampling of oil and gas and other production parameters were gathered.
The findings of these studies indicate that the first and second wells drilled there are similar in terms of the API of their oil.
What distinguishes the second from the first well was that production tests were carried out on three layers of the second one. The second well, 2,500 meters, is also deeper than the first one.