Prirazlomnaya Platform
Platform device
The special hydrometeorological conditions of the Arctic required special engineering solutions and technologies for the development of the Prirazlomnoye field. To implement the project, the Prirazlomnaya offshore ice-resistant stationary platform (OIRFP) was created, which ensures the implementation of all technological operations: drilling wells, production, storage, preparation, offloading oil to tankers, generating heat and electricity. Prirazlomnaya is the worlds first stationary platform, from which oil production began on the Arctic shelf in difficult conditions of drifting ice fields. At the moment, it is the only platform that produces oil on the Russian Arctic shelf.
The platform is designed to work in extreme climatic conditions, meets the most stringent safety requirements and is able to withstand maximum ice loads.
The length and width of the platform are 126 m, height - 141 m. The platform is reliably held on the seabed due to its gravitational weight exceeding 500 thousand tons, and after installation, it actually became an artificial island. Its gravitational stability and protection against soil washout are also provided by a crushed stone berm (its volume is over 45 thousand cubic meters), poured along the perimeter of the platform bottom. At the same time, structurally, the platform consists of several parts: a caisson where the oil storage is located, an intermediate deck, an auxiliary module, a topside, a residential module and two complexes of direct oil offloading devices (COUPON). More than 200 personnel work on the platform on a rotational basis every day with a shift every 30 days.
Round-the-clock monitoring of the Prirazlomnaya OIRFP condition is provided by a special system of more than 60 sensors that instantly respond to changes in its operation. Among similar sensors:
- Inclinometer - for measuring the inclinations of the caisson
- Strain gauge - for measuring ice loads
- Soil Dynamometer - for measuring the load on the soil
- Accelerometer - for monitoring seismic activity around the platform
- Piezometer - for measuring soil pressure from dynamic horizontal loads
Oil production and shipping
The project for the production of the first Russian Arctic oil entered an active phase in mid-2013. Prirazlomnaya provides all technological operations, including well drilling, production, storage, preparation and offloading of oil to tankers. Prirazlomnaya is the worlds first stationary platform, from which oil production began on the Arctic shelf in difficult conditions of drifting ice fields.
The supporting base of the platform - the caisson - is a unique development: it bears the main load and the reliability of the entire platform depends on its reliability. It is the caisson part that allows Prirazlomnaya to successfully withstand the Arctic climate, protect all equipment and ensure the safe work of personnel. The height of the caisson is 24.3 meters, i.e. almost equal to the height of a nine-story building.
In the caisson of the Prirazlomnaya OIRFP there is an oil storage facility consisting of 16 compartments, and above it all the other technological complexes and platform systems are located. Oil storage tanks use a "wet" method of storing oil - that is, they are constantly filled with either oil or water. This storage method excludes the formation of any explosive atmosphere, which is an additional condition for the safety of the platform.
The Prirazlomnaya OIRFP is equipped with two sets of direct oil offloading devices (KUPON) operating on the basis of a crane system and allowing tankers to be loaded from the platforms oil storage. COUPONS are located at opposite ends of the platform, which makes it possible for tankers to approach the platform unhindered in all weather and navigation conditions.
COUPON devices are equipped with a special nasal receiver. Oil is shipped through one of the devices depending on the direction of external loads (waves, ice drift, currents, wind). COUPON monitors the movement of the tanker in the 180 ° sector. If it deviates from the sector served by one device, the tanker is unmoored and transferred to another COUPON.
Special attention is paid to safety issues: oil shipment starts only when 30 necessary conditions are met at a time. The line for pumping oil to the tanker is equipped with an emergency stop and shutdown system, which, if necessary, allows the shipment to be stopped almost instantly - in a maximum of 7 seconds.
Before the start of loading operations, the shuttle tankers Mikhail Ulyanov and Kirill Lavrov, equipped with a bow loading system, carry out contactless mooring, at which the distance from the tanker to the Prirazlomnaya OIRFP is 80 ± 6 m. dynamic positioning, which, despite the wind and waves, keeps the tanker in place. The loading speed of the tanker can reach up to 10 thousand m3 / hour, which allows loading the tanker with ARCO oil in 8-9 hours. Permanent duty next to the platform is carried by specialized vessels equipped with the latest powerful complexes of emergency oil-gathering equipment for work in winter conditions.
The new grade of oil produced at the Prirazlomnoye field is called ARCO - from the initial letters of the English words "Arctic" and "oil". The new grade of oil first entered the world market in April 2014.
ARCO oil has a high density (about 24 API) and a sulfur content of about 2.3%, as well as a low wax content. Relatively heavy compared to conventional Russian export crude, ARCO is well suited for deep refining at refineries in northwestern Europe. It produces unique chemical products that can be used in road construction, tire manufacturing, space and pharmaceutical industries.
Drilling and well intervention
Since the depth of the sea in the area of ??the platform is small - only 20 meters, Prirazlomnaya is located directly on the seabed, and all wells are drilled inside it. Thus, the platform base is also a buffer between the well and the open sea.
The thickness of the concrete walls of the base is 3 meters, from above they are covered with extra strong steel, therefore such a structure is able to withstand any natural stress. For additional safety, special equipment has been installed at the wells, capable of reliably blocking oil rise at depth, if necessary.
The drilling rig on the Prirazlomnaya OIRFP is reliably protected from external influences, which allows drilling in any weather. The rigs lifting capacity is 547 tons, it can withstand a wind load of 51 m / s. Drilling is a real center of oil production at Prirazlomnaya: all wells, the total prospective length of which will exceed 200 km, are drilled from it using the directional drilling method.
In total, the project provides for the commissioning of 32 wells. They are drilled using directional drilling and are divided into 3 types: production, injection (maintain pressure in the oil-bearing formation) and absorption (in accordance with the principle of "zero discharge" is injected used drilling mud, as well as cuttings and other waste).
The entire drilling process on the platform is controlled by specialists who take all geological and technical parameters and, in case of emergency, will be able to shut off the wellhead and prevent possible blowouts.
Industrial and environmental safety
Prirazlomnaya is designed to ensure maximum safety of oil production. When designing it, the experience of the leading American, Canadian and Norwegian oil and gas companies, which have been producing in similar natural and climatic conditions for several decades, was taken into account.
Wind and freezing temperatures in the mining area prevail 40% of the year, the number of storms reaches 22 per year with an average storm duration of 9.5 days, stable ice cover lasts 7 months a year from November to May. The platform is designed to ensure the maximum safety of oil production in the Arctic region, is designed for maximum ice loads and is able to withstand the impact of a 10 m high wave.
Prirazlomnaya is a new industrial facility (its active construction began in 2008), it is equipped with all the equipment necessary for safe operation. The platform is protected from wave and ice influences by a special design - a deflector made of high-strength steel. It is a 16.4 m high wall, the inclined upper part of which prevents overflow of incoming waves.
For greater resistance to corrosion and wear, the walls of the caisson are made of a 4 cm thick layer of clad steel, the three-meter space between which is filled with ultra-strong concrete. To protect against high humidity and aggressive marine environment, a special paint and varnish coating and cathodic and anodic protection systems are used. The safety margin of the platform base is many times greater than the actual loads - it is capable of withstanding even a direct torpedo strike.
The Prirazlomnaya OIRFP operates in accordance with the “zero discharge” principle. Used drilling mud, cuttings and other waste are pumped into a special absorption well. In turn, the oil and oily water collected by the drainage system and purified oil and oily water, contaminated rainwater and snow will be pumped back into the reservoir to a great depth, which is considered in world practice to be the safest way of waste disposal.
The Prirazlomnaya OIRFP uses an automated control and safety system (ACS). Remotely and automatically, the ACS controls the production, preparation, storage and shipment of oil, the production and distribution of electricity. The automated control system also monitors the fire and gas situation, emergency shutdown of equipment and technological processes.
The platform has all the necessary systems that ensure safe conditions for the execution of production processes, as well as means of rescuing people working on the platform. Evacuation and rescue systems for personnel on the platform include evacuation corridors with emergency lighting and fire resistance of walls for 120 minutes, temporary shelter for personnel on the mezzanine deck, evacuation bridges and SES-2D systems with sleeves and life rafts, personal rescue equipment (life jackets, circles , immersion suits), tanker-type lifeboats for lowering onto the open water surface.
