The GSF High Island IX rig, operational in the region.
The well head platform of the rig.
The Okwok field is located close to OML 123, shown here operated by Addax.

Okwok oil field is spread over 22,500 acres in oil mining licence block 67 (OML67) off the coast of Nigeria. Oriental Energy operates the field with a majority stake of 60%. The remaining stake is owned by Afren (28%) and Addax Petroleum (12%).

In March 2010 Oriental and Afren secured a new $450m reserves-based lending debt for the development of Okwok and Ebok fields. The debt financing was arranged by BNP Paribas, Natixis and Credit Agricole Corporate and Investment Bank.

Afren plans to drill five appraisal wells, six production wells and one exploration well in Okwok by the first quarter of 2011. The first appraisal well is expected to be spudded in the third quarter of 2010.


The field was discovered in 1967 through the discovery well Okwok-1. The discovery was made by a joint venture between Nigerian National Petroleum Corporation (NNPC) and Mobil Producing Nigeria, a subsidiary of ExxonMobil.


The field is situated about 45km off the coast of Nigeria, in water depths of 35m to 50m. The Ebok field which is being developed by Afren and Oriental is just 15km away from Okwok.

“The field was discovered in 1967 through the discovery well Okwok-1.”

Significant synergies are believed to be derived if Okwok is developed by sharing Ebok field’s infrastructure including storage and offloading facilities.

Okwok is also situated near to the Addax operated OML 123, increasing the scope of synergies the company would derive by sharing the existing infrastructure.


The Okwok field area is categorized into three main fault blocks, designated Block 1, Block 2 and Block 3. The field contains a pattern of Plio-Pleistocene age sandstones which are also called Lower D Sands. These sands are found at a drill depth of 3,000ft to 4,000ft subsea.

Okwok reserves

According to the latest estimates, Okwok contains more than 70m barrels of recoverable oil reserves. The stock tank oil initially in place (“STOIIP”) is estimated to be 225m barrels of oil.

Field development

The field appraisal was initiated by drilling two wells, Okwok-2 and Okwok-3, in 1968. The wells, however, were not production tested.

Oriental joined the field development by executing a farm-in agreement with the ExxonMobil / NNPC JV on 9 May 2006. In June 2006, Addax acquired 40% interest in Okwok and became a technical advisor and joint venture partner to Oriental in the field development.

“According to the latest estimates, Okwok contains more than 70m barrels of recoverable oil reserves.”

Following this, Oriental completed the Phase One Appraisal and Exploratory Drilling Program for the field in October 2006. The program included drilling of two appraisal and two exploratory wells namely Okwok-4A, Okwok-4ASTI, Okwok-7A and Okwok-8A. The first two (4A and 4ASTI) were appraisal wells in Block 2 while the third (7A) and fourth (8A) were exploratory wells in Block 3.

A sidetrack and three more wells, namely Okwok-4st, Okwok-4ST1 and Okwok-8, were drilled during the same year. Two of these wells, which were flow tested, recorded production rates of 400bbl/d and 1,220bbl/d.

Afren joined the Okwok development in August 2009 when it signed a farm-in agreement to acquire 28% stake in the field. The agreement was signed with Oriental and Addax, and requires Afren to fund the entire costs of the initial exploration or appraisal well. All the subsequent capital and operating costs of the field development will be funded by Afren and Addax on a pro-rata basis according to their respective net share in the field. The revenues will also be shared on the same basis.

Drilling equipment

GSF High Island IX drilling rig was used for the four appraisal wells of the Phase One Appraisal and Exploratory Drilling Program in 2006. It is a 250ft jack-up rig owned by Transocean.

Afren and Oriental have signed a contract with Transocean in March 2010 for the supply of a rig that would be used for drilling at Ebok / Okwok.