Bouri Field Explained

Bouri Field
Country:Libya
Locblock:Pelagian Basin Block NC41
Offonshore:Offshore
Operators: Eni
Partners: National Oil Corporation
Discovery:1976
Startofproduction:1988
Peakofproduction:NA
Expectedabandonment:NA
Currentproductionoil:60000oilbbl/d
Currentproductiongas:NA
Estimatedstoiipoil:NA
Estimatedstoiipgas:NA
Producingformations:Bou Dabbous-Tertiary

The Bouri Offshore Field is part of Block NC-41, which is located 120 kilometers (70 miles) north of the Libyan coast in the Mediterranean Sea. It was first discovered in 1976 at a depth of 8700feet and is estimated to contain 2Goilbbl in proven recoverable crude oil reserves and 2.5Tcuft of associated natural gas with an annual production potential of 6 billion m³. Bouri is considered the largest producing oilfield in the Mediterranean.[1]

Discovery and development

Overview

In 1974, the Italian oil company Eni S.p.A signed a Production sharing agreement (PSA) awarded by the state-owned National Oil Corporation (NOc) of Libya for onshore and offshore exploration in areas near Tripoli. This is where the Bouri field was discovered offshore at a depth of 8700feet in the Gulf of Gabes by Eni's subsidiary company Agip Oil in 1976. The Bouri field is jointly operated by Agip and NOC, with production initiating from two oil platforms (DP4 and DP3) in August 1988. By the end of 1989 it was producing an average of 60Moilbbl/d. The first phase of development, costing nearly $2 billion, was completed in 1990. This was immediately followed by commencement of a second development phase which entailed the drilling of 55 new wells and construction of three additional platforms.

In 1995, the Bouri field was producing nearly 150000oilbbl/d, followed by a sharp decline to 60000oilbbl/d in 1998. This decline was largely a result of the country's inability to import enhanced oil recovery (EOR) equipment under United Nations sanctions, specifically UN Resolution 883 of November 11, 1993, which banned Libya from importing refinery equipment. The situation has improved since the UN Security Council officially lifted sanctions against Libya during September 2003 and foreign investment is expected in the future. In 2006, Eni reported that the Bouri field was producing about 55 kbboe per day.[2]

Block NC-41 Facilities

Block NC-41 contains three known petroleum reservoirs; one oil reservoir and two gas reservoirs. NC-41 has two production platforms: DP4 and DP3. The latter is tied back to the DP4 platform located 6.5 km northeast. The DP4 platform is permanently moored at a single point to a Floating Production Storage and Offloading (FPSO) tanker with a storage capacity of approximately 1.5Moilbbl. Bouri has three subsea wells independently tied to the DP3 platform by underwater safety valves (USV) mounted on a subsea-deployed skid located 150 meters from the DP3 jacket. The three wells were initially drilled in 1994-1995 and temporarily abandoned until completion in 1998. The subsea trees are an integral protection structure for deflection and protection, preventing the release of oil or gas from wells into the environment and controlling formation fluids. The wells, notable for Hydrogen sulfide, are controlled by chokes on subsea trees. Hydrocarbons are produced by their respective underwater safety valves to the DP3 platform through flexible 4" nominal-diameter flowlines. Topside controls were installed by FMC Technology on the DP3 platform and use a multiplex electro-hydraulic control system with independent production umbilical at each well.

Field Development Since 2004

In 2004, Agip Oil commissioned Saipem S.p.A. for additional development projects related to the Bouri Field. The project carried out through a joint venture between Saipem and Korea’s Hyundai Corporation, which fabricated process and utility modules. Apart from drilling modules, designed and with fabrication follow up by Saipem, the contract covered installation of two drilling and production platforms in 160 meter water depths. Overall, twenty-seven modules, ranging in weight from 500 to 1700 tons, and totalling 26,000 tons, were installed. Work conducted on the Bouri Field DP-4 Rig, included; a Removal project: decommissioning and removal of one of the two drilling rigs and associated modules from the DP-4 platform. These operations were carried out utilising the Saipem 7000, which is the world's second largest crane vessel.[3]

Export Development

The Western Libyan Gas Project is a 50-50 joint venture between Eni and NOC which came online in October 2004. This project transports natural gas from Bouri and other Eni fields through the $6.6 billion, 32inches, 520 km Greenstream underwater pipeline. Currently, 280Gcuft per year of natural gas is exported from a processing facility at Melitah, on the Libyan coast, via Greenstream to southeastern Sicily. From Sicily, the natural gas flows to the Italian mainland, and then onwards to the rest of Europe. Throughput on the Greenstream line reportedly can be boosted to 385Gcuft per year.[4]

Djeffara-Pelagian Basin Province: Formation

The Bouri field is situated in the Djeffara-Pelagian Basin Province (also known as the “Pelagian Basin”), and produces from the Bou Dabbous-Tertiary TPS. The Province is primarily an offshore region of the Mediterranean, located off eastern Tunisia and northern Libya (northwest of the Sirte Basin), and extending slightly into Italian and Maltese territorial waters. The Pelagian Province contains over 2.3Goilbbl of known (estimated total recoverable, including cumulative production plus remaining reserves) petroleum liquids; consisting of about 1Goilbbl of recoverable oil reserves and approximately 17Tcuft of known natural gas. It is speculated that Tertiary carbonates might contain indigenous hydrocarbon sources, particularly in Eocene rocks (Gir Formation), that could have contributed to the large reserves in Djefarra-Pelagian. In addition to Bouris, other major fields located in the province are the Ashtart and Sidi el Itayem fields.[5]

References

Notes and References

  1. http://www.slb.com/media/services/resources/mewr/num1/success.pdf Middle East Reservoir Review
  2. http://www.eni.it/eni/internal.do?RID=@2391yM 0?xoidcmWopk&lang=en&sessionId=22107205 Libyan Operations
  3. L. Petrilli (1992) Saipem: Bouri project
  4. B. Michalski Mineral Industry of Libya USGS
  5. T. Ahlbrandt (2002) p.17; and Petroconsultants (1996)