Okume Complex, Equatorial Guinea

The Okume development achieved first oil on December 14, 2006, when the Okume B platform came on-stream. Production will grow during 2007 as in-field drilling progresses until gross peak production of 60,000bpd is achieved during 2008.

The development is located in block G offshore Rio Muni, in the Gulf of Guinea, 55km southwest of Bata and 250km south of Malabo. The Okume complex is based on the draining of the Oveng and Okume / Ebano and Elon reservoirs.

The field is operated by Hess with an 85% working interest on behalf of its partners Tullow (14.25%) Oil and GEPetrol. Construction of the Okume complex facilities began in August 2004, following approval of the plan of development by the Republic of Equatorial Guinea.

OKUME FIELD DEVELOPMENT

The field is being developed by two tension-leg platforms as well as three satellite well protector platforms and a central processing platform in the Elon reservoir area. These facilities provide for full-field pressure maintenance and artificial lift capability.

The Okume complex central processing facilities are tied back to the Sendje Ceiba Floating Production Storage and Offloading (FPSO) vessel, which provides crude storage and loading capability.

FIELD DISCOVERY

The field was discovered by the Okume-1 oil well, which recorded 200ft of net pay. Following this, Hess carried out an appraisal programme with Okume-2 and Okume-3, drilled and sidetracked. The wells encountered 153ft and 137ft of net pay respectively, penetrating good quality reservoirs.

Okume-2, located 1.3 miles west-southwest of Okume-1, was drilled to a total depth of 8,500ft in 1,814ft of water. Okume-3 well is located 1.7 miles north-northwest of Okume-1 and was drilled to a total depth of 9,570ft in 2,080ft of water.

The development is planned to be based on a combination of 43 oil producers with gas lift, water injection and gas injection wells. Approximately 23 of the wells will be drilled and completed from the two TLPs. The remaining 20 wells will be drilled and completed from three fixed platforms.

OKUME CONSTRUCTION

In October 2004, MODEC was awarded the contract for the TLPs on the Oveng and Okume / Ebano Field. The Oveng TLP is installed in approximately 275m (902ft) of water while the Okume / Ebano TLP is installed in approximately 510m (1,673ft) of water. They were both built in the Samsung Heavy Industries yards in South Korea. MODEC was responsible for design, engineering, procurement and construction of the hulls, topsides, mooring, drilling riser, and production riser systems.

Both platforms are designed to support up to 18 top-tensioned production and/or water injection direct vertical access risers and a tender-assist drilling unit. The platforms provide initial processing of up to 25,000bpd of oil – 30 million cubic feet a day, water treatment and utility systems to support a ten-person operations group.

A new Self Stable Integrated Platform (SSIP) design allowed the platforms to be fully integrated (deck mated with the hull) in the shipyard, thereby providing installation and hook-up cost savings.

The trees were supplied by FMC. The surface dry trees are rated to 5,000psi with a 4-1/16in tree bore size. The field development is based on 23, 10-3/4in OD production risers systems including tieback connector, stress joint, riser joints, keel joint, tension joint and fixed tensioner system.

Each tree includes a 16-3/4in rigid lock subsea wellhead system to 10,000psi and a surface wellhead and tree systems. There is also a 18-5/8 OD surface BOP drilling riser system with tieback connector, stress joint, riser joints, keel joint, tension joint, hydropneumatic tensioner system and BOP adapter.

For the fixed platforms, there are 20 surface wellhead and tree systems including casing head, tubing head, tubing hanger and subsea tree. The pipe was supplied by Tenaris. In total, 88,087m of X65 seamless pipe was used for subsea flowlines, which were manufactured at the steel mills in Italy and Argentina. The pipelay was carried out by Acergy.