Prirazlomnoye Oil Field: the Start is Coming

Prirazlomnoye oil field is the pilot project in developing Russian Arctic shelf. It was disclosed in 1989 by State Industrial Company Arktikmorneftegasrazvedka. So far, at the field four test/exploratory holes have been drilled; three of them were found with industrial oil-inflows.

Sevmorneftegaz was founded in 2002 as an investor and operator for Prirazlomnoye oil field development. It is licensed for managing Prirazlomnoye oil and Shtokmanovskoye gas-condensate fields.

However, now our main goal is to complete as soon as possible modernization of the crest structure of the Hutton TLP platform that had been purchased 2 years ago in Norway. Such modernization is being carried out by Production Association Sevmashpredpriyatiye. In May 2007 Prirazlomnaya platform will be towed from Severodvinsk bay, first – to Severomorsk for concreting, then – to the oil field. After it is planted on the seabed at the water depth of 20 m, extraction of the first oil will be commenced.

Prirazlomnoye oil field construction and development project is the first project for the environment of the Arctic region of Russian European North. It is being implemented by using Russian scientific, design and industrial capabilities. This project is unexampled in the world practice. All procedures/operations will be carried out by means of one platform only in the difficult ice conditions of the Arctic shelf.

Prirazlomnaya platform is of gravitational type; it is made out of steel structures with concrete used for ensuring local stability as well as for ballasting. It has positive buoyancy and is to be delivered to an oil field with production equipment mounted-on.

In operational conditions, it rests on the seabed without any additional securing. Its on-ground stability is provided by its own weight and water and concrete ballast. Offshore Ice-resistant Fixed Platform (OIFP) will be placed on the seabed with vertical accuracy of ±0.5° in any direction. The platform provides storage of up to 109 thousand m3 of oil prepared for transportation, that complies with five- or six-day capacity during maximum extraction period.

The platform is designed for whole-year continuous operation if regularly supplied with necessary materials and food in each 15-60 days. Platform works are carried out by rotated teams. The staff is 150 persons, teams are rotated each 14 days.



The major part of capital investments is the cost of OIFP that is the principal object for oil field construction. At the platform, whole-yearly continuously all principal and secondary processing operations will be carried out, namely:

  • simultaneous boring and operating wells;
  • oil preparation for transportation;
  • oil storage, within 109 thousand m3;
  • loading oil to tankers;
  • loading/unloading of supplies;
  • waste recycling according to “zero discharge to environment” principle;
  • rotating accommodation of staff;
  • landing and refueling of helicopters;
  • purification of formation water and ballast water and its injecting into the developed oil stratum;
  • generating electric power for platform own needs;
  • control of processing operations and monitoring of the platform structures and external effects;
  • external communication with onshore and offshore facilities.

OIFP is equipped with all systems required for safe processing, labor and rest of the staff, environment pollution protection, as well as with platform staff salvage means in case of accident.

Besides Prirazlomnaya OIFP, oil field construction objects include:

  • onshore oil field support bases;
  • terminal station (TS) with floating oil storage (FOS) purposed for gathering and storing oil and for loading line tankers of 120-170 thousand tons deadweight;
  • floating transportation crafts (vessels) of various purposes;

The terminal point of oil transportation system from Prirazlomnoye oil field to product markets is the depot ship in Pechenga Bay (Devkina Zavod Bay) of Murmansk region. The depot ship includes:

  • FOS, with the berth of 220 thousand tons load capacity, pump station, bunkering base and fire-fighting equipment;
  • Auxiliary onshore structures, including ones for receiving dirty water from vessels and vessel towing, navigation control station, berth for auxiliary vessels etc.

For oil takeoff, supplying OIFP with necessary cargoes and ensuring safety of oil field construction/development works, vessels of various purposes are to be used:

  • shuttle and line tankers (ST and LT correspondingly);
  • line (nuclear-powered) icebreakers (LIB);
  • multifunctional supply icebreakers (MFSIB);
  • specialized supply vessels (SSV);
  • port vessels.

One of the main problems to be solved is oil gathering and preparing technology, so that oil parameters meet standards accepted in Russia and over the world. For this purpose development wells are equipped with submersible electric centrifugal pumps to deliver wellbore fluid onto the platform. Wellheads are provided with well-control equipment designed for pressure of 21 MPa and equipped with flow control valves and hydraulic driven valves. All wells are also provided with intrawell type shutoff valve.

On the platform there are three-phase separation units designed for two-phase flow fluctuation suppression, separation of gas from liquid products, separation of oil from free formation water and free water discharge.

Oil preparation stage includes the following basic processing equipment: electrostatic coagulators and stripping column.

From stripping column refined oil is pumped through coolers into storage containers of OIFP base by means of pump.

Gas supplied from oil separator is to be compressed and mainly used as fuel gas. Gas excess is burned with high pressure flame.

Oil recovery process goes simultaneously with output of formation water which is utilized through formation pressure sustaining system (FPS). Shortage of water for FPS is made up by using ballast and sea water. All water is to be specially treated before it is pumped into productive stratum. Field development system must provide maximum oil output from subsurface at high rate of its recovery during the whole period of field operation, and with relatively little stock of production and injection wells (19 and 16 correspondingly). Therefore, determinative factor for achievement of oil recovery design ratio is the use of the most modern field development system which should comply with its geological conditions to the utmost.

Boring of wells with long boreholes in productive stratum (up to 1000-2000 m) significantly intensifies oil recovery procedure. Field development by means of these wells is very advantageous in such geological conditions of development as big oil-saturated thickness at small field stratum anisotropy.

In future double-hole and multihole wells with long boreholes in productive stratum can prevail in sea field development.

Fulfilled calculations of development procedure testify double increase of oil flow rate for planned single-hole wells in comparison with usual vertical ones and quadruple increase for double-hole wells. Boring of double-hole wells at sites remote from the platform is especially effective, because in this case deepening in nonproductive stratum is less.

Water pumping at pressure up to 400 atm. at injection well bottom highly effecting productive stratum and pressure reduction at production well bottom down to 125 atm. from the beginning of development allow to provide high withdrawal of oil in wells.

Intensification factors listed above and favorable geological conditions should provide high oil flow rates for the whole well stock (in the initial operation period oil flow rates are 1230 - 1480 t/day), as well as big cumulative withdrawals for one well during profitable term of development - approximately 4.0 million tons in average.

As per recommended variant, planned oil production level is 6.59 million tons, or 8.8% from initially recovered oil stock. Total (cumulative) oil recovery during profitable 22-year operation period is 74.45 million tons, that corresponds to oil output factor of 32.2% (when factor approved by RF State Reserves Committee is 0.3).

Thus, one of main tasks of Prirazlomnoye oil field development is oil recovery intensification at all stages of field operation. Such measures as boring of reserve, additional, horizontal double-hole wells and earlier brining them into service also facilitate the solution of this task. Sea oil and gas field support bases and production facilities for building offshore ice-resistant platforms are going to be used for development of Shtokmanovskoye gas-condensate field and other fields of Pechora Sea shelf.

Implementation of Prirazlomnoye field development project will allow to provide new workplaces for elaboration of new technology, technical facilities and equipment for development of hydrocarbon resources of arctic shelf in the North-West region of the Russian Federation.




Recorded by Olga Loskutova

Go to Index of # 3(13) 2005

 

# 3(13), 2005
Ocean and shelf exploration

Ivan Chernov, 
Director General of Sevmorneftegaz JSC, Doctor of Science

Ivan Chernov, Director General of Sevmorneftegaz JSC, Doctor of Science