Oil Spill Response at the Prirazlomnoye Field
Marichev Andrey (LLC «Gazprom VNIIGAZ», Moscow region, Leninsky district, Razvilka), Khmarinov Leonid, Efremkin Ivan, Rogozin Maxim (LLC “Gazprom neft shelf”, Moscow)
Introduction
The Prirazlomnoye oil field is located 60 km offshore in the Pechora Sea,. The field uses «Prirazlomnaya», an ice-resistant stationary offshore platform (IRSP) for drilling, production and oil treatment (Fig. 1). The treated oil is loaded into 70 kt displacement ice class tankers and exported. The field is scheduled to start production in 2013, with maximum annual production set to be about 6.5 mln tonnes. The project is operated by GazpromNeftShelf LLC (GNS).
1. Possible Causes of Oil Spills
During the infrastructure design, a detailed analysis of possible accidents, including oil and oil product spills, was carried out. The most hazardous possible situations are as follows –
» Uncontrolled blow-out of oil (reservoir fluid) from the well during the drilling operations;
» Damage to the oil storage tank at the foundation of the offshore platform;
» Damage to some of the tanks on the oil tanker during the offloading from the platform.
It should be noted that such events are rare and the occurrence of such accidents during the project lifetime is unlikely. Accidents that are most likely to happen include the following:
» Oil and gas shows during drilling operations;
» Leakage on wellhead equipment and leakage on reservoir fluid separator feeding manifold;
» Oil spills when disconnecting loading pipeline.
However, spill volumes for these most probable accidents will not exceed 2 m3.
2. Oil Spill Prevention
It is well known that oil spill response (OSR) in Arctic conditions is very difficult, which is why GNS makes oil spill prevention its priority. Blowout preventing equipment is used during drilling operations to prevent oil spills, and each well is equipped with subsurface safety valves and hydraulic valves. Four independent power sources are used for these well containment tools – the main gas turbine generators, auxiliary diesel generators, emergency diesel generators and the tools’ autonomous power sources. Well sealing can be controlled from the platform central control room, from the drilling foreman’s control panel, or manually. However, due to low formation pressure, electric submersible pumps are used to pump oil to the wellhead, and therefore, an oil blowout at Prirazlomnoye is impossible.
To prevent oil spills during ship loading operations, the following technical solutions are used:
» Oil is stored in caisson cells in «wet storage» conditions. In «wet» storage, oil stream entering the storage unit displaces ballast water which is pumped into oil containing water treatment system for further water injection into the reservoir. When oil is pumped out into the tanker, oil is replaced with balance water from a pressure tank. With this storage arrangement, oil storage tank is constantly filled with liquid – either with oil of with outside (ballast) water. This storage method ensures safe storage of oil (absence of free gas);
» The system for offloading produced oil into the tanker is equipped with an emergency shutdown system.
The Prirazlomnaya offshore platform was designed based on «zero discharge» principle, which only allows the discharging firefighting water from water deluge system and treated domestic sewage water into the sea. Platform’s drainage systems ensure collection of all oil-containing water, polluted rainwater and snow for further treatment and injection.
3. Oil Spill Response
The Oil Spill Response Plan (OSR Plan) in effect at the offshore platform has determined the Plan’s coverage zone as the aquatic area with boundaries which correspond to the maximum possible oil product pollution area with 95% probability, with consideration of unfavorable metocean conditions, which (pollution) resulted from an accident at the platform within its safety zone. According to the Decree of the Government of Russian Federation No. 44 dated 19.01.2000, safety zone around an offshore hydrotechnical structure is 500 meters.
A standard International, tier-based approach is applied for oil spill response (OSR) planning and operations at the Prirazlomnoye field. GNS acknowledges that the company has limited ability to controll an accident, and indeed that a large accident may require outside means and forces.
Three tiers of response are accepted in OSR Plan:
» Tier 1: spill volume below 500 t. Response operations will be carried out using GNS means and forces;
» Tier 2: spill volume between 500 and 5000 t.. If unable to respond to the spill using company’s own means, GNS will engage outside regional forces and means;
» Tier 3: spill volume over 5000 t.. Such spill would be considered catastrophic and would require engaging resources on a national level.
The maximum possible spill volume is 10 000 tons. This volume equals the volumes of two tanks of a 70000 t displacement tanker and it was determined in accordance with the «Main requirements for development of oil and oil product spill prevention and response” (approved by the RF Government’s Decree No. 613 dated August 21, 2000 with changes No. 240 dated April 15, 2002).
OSR operations can be carried out in the open sea near the platform, on the offshore strip or onshore in either ice conditions or in open waters.
Management of spill response operations is undertaken by the Emergency and Fire Safety Commission of GNS. Depending on how the situation develops, the Commission may either be based at GNS facilities in the Varandey settlement or in the accommodations block of the Prirazlomnaya platform.
The rooms for the operations are provided with the following:
» OSR Plan on paper and in digital form;
» navigation maps for the OSRs operational areas;
» means of communication (telephones, fax, e-mail, radio communications);
» computers with Internet access;
» set of required normative documents;
» copying equipment.
The first stage of OSR operations includes:
» informing the state authorities, the population and interested parties;
» deployment of local OSR forces;
» monitoring of the spill, simulating its movement;
» Containment of the spill and commencement of recovery operations.
The actions of the second stage of OSR operations target updating the situation, the build-up of OSR forces and adjusting the plans based on new information.
The third stage of OSR operations includes aquatic area and shoreline final clean-up and disengaging OSR equipment.
In case of an oil spill near Prirazlomnaya platform, a rescue vessel which is permanently based 2 km from the platform starts operations. Duty boats are available both on the vessel and on the platform and may be engaged in the operations if necessary.
The oil spill movement is then monitored by GNS in cooperation with Federal Service for Supervision of Natural Resource Usage for Nenets Autonomous District. Surveillance and tracing of the oil spill is done from onboard the ship and/or with a helicopter. Special software is also used to simulate the migration of the spill.
According to the Russian legislation, oil product spills in open sea must be contained within four hours. Booms are used to contain the spill, which increases the efficiency of oil response methods. However, oil can be cleaned up without boom deployment.
The main method of cleaning the spill in the open sea is mechanical cleanup. Selection of the oil spill response method and equipment used will be determined by the conditions of any specific situation. Below is the list of main equipment for OSR operations in the open sea.
We should note that GNS is dedicated to using advanced technologies to meet the challenge. Thus, GNS was the first in the world to place an order for a 100 m3/h capacity ice oil skimmer, the latest development from Aker Arctic.
Principal Oil Response Equipment for Open Sea Spills
» Self-propelled oil skimmer 100 m3/h capacity for open waters;
» Arctic oil skimmer 100 m3/h capacity for ice conditions;
» Vessel side-mounted oil skimming system up to 115 m3/h capacity;
» Inflatable booms, 1200 m;
» Adsorbent.
In case the shoreline is affected, OSR operations will commence immediately on the coastal area. Equipment for such operations is stored at the base in Varandey and is intended for coastal zone protection operations both offshore and oil pick-up onshore.
Equipment and personnel are delivered to the location using off-road vehicles and/or boats. The principal OSR method for the coastal area is mechanical clean-up, while using absorbents would be efficient onshore. Below is the list of the main equipment.
Principal Oil Response Equipment for the Coastal Area Offshore operations
» clean-up and boom setting motor boat:
• up to 15 knots speed;
• cruising range up to 350 miles;
• volume of tanks for collected oil and oil products 30 m3;
• cargo hold 15 m3;
• 2 person crew.
» marine boat:
• up to 6 persons capacity;
• carrying capacity 1500 kg;
• 6 knots working speed;
• maximum speed – 25 knots (with no load).
» brush oil skimmer machine 80 m3/h capacity (onboard the motor boat);
» Portable skimmer 80 m3/h capacity, 4 ea.;
» Permanent floatation booms, 2000 m;
» 10 m3 capacity inflatable floating storage tanks for collected oil, 4 ea.;
» Shoreline protection booms, 300 m;
» Absorbent booms, 500 m.
Onshore operations
» Marsh buggy (for equipment transport), 2 ea.;
» Track-based vehicle for equipment transport;
» Manual oil pickup system for onshore clean-up, 2 ea.;
» 4 m3 tanks for oil cleaned up onshore, 5 ea.;
» 50 l/min capacity sorbent spraying machine, 2 ea.;
» Absorbent, 500 kg;
» 2 t/hour polluted dirt disposal system;
» lighting mast 4 kW with 9.5 kW generator, 4 ea.
The issue of entering an agreement on oil spill response assistance with the Varandey terminal operator, Lukoil-trans, LLC is being considered. Indeed, an agreement of intent has been signed. If necessary, the forces and means of GNS and LUKOIL-Trans could be joined for oil spill response operations. The quantity and range of OSR equipment at Varandey Terminal are comparable to above listed.
4. Provisions for OSR Operations
After cleaning up a large oil spill, a lot of time is spent on damage assessment and compensations to the parties involved, or those affected by the spill.
Considering the significant scale of financial expenditures, all stages and operations of OSR are documented in detail listing type of works, number and qualifications of staff involved, labor costs, equipment and consumables used.
Activity timelines and navigation routes for vessels, floating and other technical equipment etc are registered in ship logs, Emergency Commission’s event log as well as in reports and other documents.
GNS has formed a reserve fund to finance possible emergency response operations and has also made public liability insurance provisions. OSR operations are financed by GNS (with any costs to be reimbursed by organizations responsible for the spill as established by law).
During the OSR operations, a financial department headed by the Chief Accountant of GNS, will be established to finance all expenditures, handle claims and provide compensation of damages.
GNS pays special attention to the issues of OSR staff training. Along with regular trainings, oil spill response drills in open water and in ice conditions are done annually.
A program for monitoring the aquatic area of Prirazlomnaya platform, implemented by GNS, will contribute to increasing the efficiency of OSR operations. For a few years now, contractor companies have been carrying out annual surveys on updating the environmental situation in this region. Environmental monitoring activities on Dolgiy Island are planned for 2013.
Conclusion
The Company’s technical and organizational solutions on oil spill prevention and response comply with the requirements of relevant Russian rules and regulations, and also correspond to international practices in this field.
By the time drilling operations commence, the offshore platform and onshore base in Varandey will be completely equipped with OSR equipment, including the latest foreign-manufactured models.
It should be emphasized that an oil blow-out from a well at the Prirazlomnoye field is impossible due to low formation pressure, which significantly decreases the chances of large oil spills at the platform and rules out any chances of repeating the Deepwater Horizon accident that occurred
in 2010.
At the same time, GNS acknowledges the challenges of oil production and transportation in the Arctic and will continue improving its oil spill prevention and response measures.
Literature
1. Planning oil spill prevention and response operations for Prirazlomnoye oil field /M.N. Mansurov, A.V. Marichev, I.M. Yefremkin // Arctic: ecology and economy. – M.: 2011, No. 2. – P. 36-41
2. Main requirements for development of oil and oil product spill prevention and response, approved by the RF Government’s Decree No. 613 dated August 21, 2000.
3. Regulations on organization of oil and oil products spill prevention and response on the territory of Russian Federation, approved by Decree of the RF Government No. 240 dated 15.04.02.
