The Topacio field, which is part of ExxonMobil’s Zafiro project in Equatorial Guinea, came onstream in 1997 ahead of other deepwater fields in the region.

Equatorial Guinea’s current oil reserves are estimated at 1.1. Bbbl, and though Nigeria’s reserves are projected to reach 40 Bbbl and Angola has estimated oil reserves of 13 Bbbl, Equatorial Guinea is a smaller country in comparison and can still be regarded as well endowed in hydrocarbon resources.

Hydrocarbon production is the basis of the country’s economy and consists of crude oil, condensate, natural gas plant liquids, and dry natural gas.

According to the International Monetary Fund’s data, the hydrocarbon sector represented more than 90% of government revenue and about 98% of export earnings for Equatorial Guinea.

ExxonMobil and Ocean Energy in 1995 discovered the Zafiro oil field, which is located northwest of Boko Island in Equatorial Guinea, and it is currently the main producing field in the country.

Oil officials in Malabo, the Equatorial Guinea capital, said the Zafiro field continues to be the single largest source of the country’s oil output; field production has been in decline since it peaked at 278,000 b/d in 2004 and went down in 2006 at over 240,000 b/d. ExxonMobil reported that crude oil production from the Zafiro field on Block B decreased by about 15% in 2011 compared with that of 2010.

The continued decrease was attributed to the depletion of the producing reservoirs. In 2011 Mobil Equatorial Guinea Inc., a subsidiary of ExxonMobil, completed an eight-well infill drilling program that resulted in the addition of more than 25 MMbbl of crude oil reserves. Oil is also produced from the Ceiba and Okume fields.

But Equatorial Guinea officials expected its declining output to rise as from 2012, driven by new production from the Aseng oil and gas field offshore Equatorial Guinea, which lies at a 945 m (3,100 ft) water depth.

The total cost of the field development was estimated at US $1.3 billion. Noble Energy is the operator of the Aseng field and holds 40% interest in the project. Other partners include Atlas Petroleum International (29%), Glencore Exploration (25%), and PA Resources (6%).

According to the country’s officials at its Ministry of Mines, Industry and Energy, oil production at Aseng, situated in Block 1 offshore Bioko Island, began in November 2011 and has about 120 MMbbl of liquids over the project’s lifespan.

Gabriel Mbega Obiang Lima, Equatorial Guinea’s Minister of Mines, Industry and Energy said the country expects oil production to rise to 300,000 b/d in 2012 from 244,000 b/d in February 2011, thanks to the start of the Aseng field, which he explained will add 50,000 b/d.

New oil production in Equatorial Guinea also is expected in late 2013 from the Alen gas-condensate field, which lies in Block O, where the original discovery was made, and extends into the northern part of Block 1 offshore Equatorial Guinea.

Noble Energy announced that the Plan of Development for the Alen condensate/gas-recycling project in Equatorial Guinea has been approved by the government. The company’s board of directors sanctioned the project in December 2010, followed closely by the approval of all partners.

The company stated that initial field development will include three production wells and three subsea natural gas injection wells tied to a processing platform. Produced condensate will be separated and piped to the Aseng FPSO vessel on Block I, approximately 24 km (15 miles) to the south, where it will be held until sold. Associated natural gas will be re-injected back into the reservoir to maintain pressure and maximize liquid recoveries.

The Alen processing facility will be located in approximately 73 m (240 ft) of water and is designed to handle 440 MMcf/d of natural gas and 40,000 b/d of condensate. First production at Alen is estimated to commence by year-end 2013 at a rate of 37,500 b/d gross. Natural gas reinjection is estimated to be 380 MMcf/d during gas-recycling. The total cost of development is estimated at $1.6 billion.

“Strong operational execution at Aseng has resulted in an average production rate of 60 Mb/d gross with over 99 percent uptime since start-up in November 2011,” the company said.

Noble added that it has applied learnings from the major project development at Aseng to the Alen project, which is ahead of schedule. The well operations are complete and the platform is preparing for load out. The platform installation is planned for 2Q 2013 and first production is expected in 3Q 2013.

Production also is going on at oil fields such as Ceiba and the Okume Complex located just offshore of Rio Muni in exploration Block G while recent successful appraisal drilling at Carla, an oil discovery located beneath the Alen field, is moving ahead with project sanction expected in 2013.

In spite of political instability, Equatorial Guinea has become a major oil producer. Though it is difficult to project its future reserves, officials say exploration efforts could push the region’s reserves to 3 Bbbl in the next few years.

Obamefi Oredein, Special to E&P

Offshore