Offshore deepwater fields
The Erha deepwater development, including the Erha field and Erha North satellite field, was completed in 2006.
The fields are located approximately 97km offshore Nigeria, in water depths ranging from 1,000m to 1,200m. They were developed with an investment of $3.5bn.
Production from the main field started in April 2006, while production from the satellite field started in the third quarter of 2006. The production capacity from the development prior to the expansion was 140,000 barrels a day.
The Erha North Phase II development project, an extension of the existing Erha North subsea system and infrastructure was completed in September 2015, five months ahead of schedule. The final investment decision for the project was made in early 2013.
The project involved the further development of Erha North field by drilling wells from a new drilling centre, installation of associated subsea facilities, and modifications to the existing floating production, storage and offloading (FPSO) unit. The development aims to target a peak production rate of 65,000 barrels of oil per day (bopd) from the satellite field.
Erha fields are located in Oil Mining Lease (OML) 133, which was formerly Oil Prospecting Lease (OPL) 209.
Esso Exploration and Production Nigeria (EEPNL) is the operator, holding a 56.25% participating interest in OML 133 contract area, while Shell Nigeria Exploration and Production Company (SNEPCO) holds the remaining 43.75% share.
Bonga is the first deepwater project for the Shell Nigeria Exploration and Production Company (SNEPCO) and for Nigeria.
The Erha discovery was made in December 1999. Three appraisal wells were drilled subsequently and two wells confirmed the presence of oil in Miocene turbidite sands.
The two fields are estimated to hold combined recoverable oil reserves of approximately 500 million barrels.
The Erha deepwater development was the first deepwater offshore fieldin Nigeria. Three drill centres, comprised of 30 subsea wells, are tied back to the Erha FPSO vessel.
The drill centre east (DCE) and drill centre west (DCW) are located 1.5km from the FPSO, while the drill centre north (DCN) is located eight kilometres from the two drill centres and is tied back to DCE.
Processed oil from the project is stored in the FPSO and conveyed to offloading tankers via two 22in diameter offloading lines and a catenary anchor leg mooring (CALM) offloading buoy.
The spread-moored Erha FPSO has a designed storage capacity of 2.2 million barrels of crude oil, and its designed oil processing capacity is 210,000 barrels per day (bpd). The FPSO’s water injection capacity is 150,000bpd, and gas injection capacity is 340 million standard cubic feet per day (Mscfd).
The FPSO is 285m-long and 63m-wide, and has accommodation facilities for 100 people. It is designed to operate for 25 years and also equipped with a helideck.
An engineering, procurement, construction and installation (EPCI) contract for the project’s subsea umbilical, risers and flowline (SURF) facilities and EPCI contract for new facilities on FPSO’s topsides was awarded to Subsea 7.
The company employed its Seven Borealis, Seven Pacific and Simar Esperança vessels for the project.
Subsea 7 subcontracted Trelleborg to supply its Vikotherm S1 silicone thermal insulation solution for the project’s oil and gas flowlines. Detailed engineering for the modifications to FPSO and the field’s subsea system as part of the current project was performed by Technip’s affiliate, Crestech.
Subsea production systems comprised of five subsea production trees, two water injection trees, three manifolds, production and topside controls, and associated equipment were supplied by Cameron Offshore Systems Nigeria.
The company further subcontracted Aveon Offshore to perform the fabrication and load-out of these subsea production systems.
Seadrill was awarded a $497m contract to provide its West Saturn drillship for operations at the project site for a period of two years, which is extendable by one year.
West African Ventures was contracted to install certain manifolds and provide a DP3 accommodation vessel and a number of ancillary marine support vessels for the project.
In March 2013, Aker Solutions was awarded the contract to supply the umbilicals for the project. Comprised of two dynamic and two static steel tube umbilicals, they cover a total length of 16.5km.
Engineering, procurement and construction (EPC) contractors for the FPSO, the tieback systems and subsea system were Saipem, Acergy Services, and Cameron International respectively. The FPSO was towed to the project site by Giant Marine.
Saipem subcontracted Malaysia Shipyard and Engineering (MSE) and Sembawang Marine Offshore Engineering (SMOE) for the fabrication, integration, pre-commissioning and commissioning of the FPSO’s topsides modules.
The hull, living quarters and helideck of the FPSO were constructed by Hyundai Heavy Industries.
SMOE further subcontracted MMC Oil & Gas Engineering (O&G) to provide the detailed structural engineering and design for the electrical and instrument (E&I) modules of the FPSO. The CALM buoy was constructed by SBM Offshore.
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