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Equatorial Guinea

Department of Mines and Hydrocarbons
Ministry of Mines and Energy (Ministerio de Minas y Energia)
Technical Advisor
c/o Ministerio de Minas, Industria y Energia,
Carretera de PuntaEuropa, Malabo,
Republica de Guinea Equatorial
Tel:+240 222 277502 
shawd@rpsgroup.com
http://www.equatorialoil.com/

CIA Factbook
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Spanish-English online dictionary
French-English online dictionary
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The contribution of mining to total exports in 2010 amounted to 0.8%

Equatorial Guinea Mining News

Source: CIA Factbook


Legend
Legend and ore deposit name
Geology
Precambrian crystalline basement metamorphic sequences underlie most of the central and eastern mainland of Equatorial Guinea while Mesozoic, Neogene and Quaternary sediments are exposed along its coastal and western zone. The basement sequences are part of the Congo Craton and comprise granitic-gneiss, greenstone, schist-amphibolite and, dominantly younger, undifferentiated granitoids. The Atlantic Ocean volcanic islands of Pagalu (Annobon) and Bioko (Fernando Poo) are part of the Cameroon Volcanic Line (CVL).

Mining

Equatorial Guinea has the highest GDP per capita in Africa (estimated at US$37,800 in 2008). Hydrocarbons (crude petroleum and derivatives such as LNG, LPG and methanol) dominated the minerals industry and accounted for about 88% of GDP in 2007.Non-fuel mineral output was confined to a small amount of artisanal gold and some construction materials. Undeveloped mineral resources reported include titanium, iron ore, manganese, bauxite, uranium, and gold.
 Oil & Gas
It is Africa’s seventh largest producer of crude petroleum (3.65%) and ninth largest producer of natural gas (0.6%). In 2008 crude oil and natural gas production decreased by 1.65 per cent and 5.0 per cent respectively. This decline is expected to become more noticeable in coming years. At the beginning of 2009 Equatorial Guinea had proven reserves of 150 Mt of crude oil and 36.81 billion m3 of natural gas. Non-fuel mineral output was confined to a small amount of artisanal gold and some construction materials. Undeveloped mineral resources reported include titanium, iron ore, manganese, bauxite, uranium, and gold.
Geological Review

The mainland of Equatorial Guinea (Rio Muni) offers the wide variety of mineral potential that is expected on an Archaean cratonic setting with later Pan-African overprinting; with possibilities for gold, diamonds, columbo-tantalite, platinum-group elements, bauxite and base metals.
Rio Muni comprises the Archaean terranes of the Ntem Complex and the Monts de Cristal Massif of the northern Congo Craton, both of which were partly re-worked during the Paleoproterozoic Eburnian orogeny. They consist of largely granitic gneisses, charnockites, mafic intrusions and broad mylonitic shear zones (including an Eburnian terrane boundary), with subordinate amounts of banded ironstones, metasediments, and post-orogenic intrusions. Pan African transpressional structures are common in the west and are associated with granitic intrusions and pegmatite bodies, which also occur throughout the interior. Sub-greenschist shales, argillaceous dolomites, and quartzites occur in the southwest. Higher-grade sedimentary packages, also attributed to the Pan-African, are found along the northern border of the country where they are associated with major strike-slip and thrust faults and post-tectonic granitic intrusions.
The coastal strip of Rio Muni comprises Cretaceous sands, shales, and carbonates with basal conglomerates, all deposited during the rifting phase of Atlantic opening. Trans-Atlantic fracture zones link to major onshore lineaments, at least one of which shows evidence of Cenozoic rifting (the Benito Rift).

MINERALS EXPLORATION HISTORY

In pre-colonial times Equatorial Guinea was known for gold and iron production however there are no records of any commercial production during the Spanish era, which ended in 1968.
After independence, early investigations highlighted the potential for gold, base metals, bauxite and pegmatite minerals such as tin, tungsten and columbo-tantalite. Initial systematic surveys were conducted from 1975 by Soviet Union geologists and from 1980-1985 BRGM (France) undertook regional and follow-up alluvial heavy mineral and geochemical exploration. Between 1981-1983 GEMSA (a Spain-Equatorial Guinea joint venture) prospected for gold, iron ore, ornamental stone, molybdenite, columbo-tantalite, bauxite and diamond opportunities. In the process, GEMSA undertook airborne magnetic surveys and constructed a SLAR mosaic of the country at 1:1,400,000 scale (about 20m resolution).
From 1996 to end 2000, UMCEG (Ocean Energy) held a contract area covering the whole of Rio Muni but with operatorship from 1998 being with joint venture partner BoMc. Early investigations included data compilation and regional reconnaissance work. Detailed sampling was undertaken in the Coro gold area, around nickel anomalies in the southwest and for heavy minerals in beach sands. Programmes included soil and sediment sampling using augers and development of a GIS database.
Beginning in 2001 Exploration Consultants Limited (now RPS Energy Limited) undertook a review of diamond exploration opportunities in the Nsork area of Rio Muni on behalf of the government and an investigation of columbo-tantalite occurrences in the Aconibe district for Afex International Inc.
In 2003 a Ministry review of silica sand reserves was completed as well as field and laboratory studies to assess limestone in southwest Rio Muni with a view to potential cement production.
In 2004, on behalf of the Romanones Reed Group LLC, Fugro flew a detailed gradient aeromagnetic and spectrometer survey as part of a reconnaissance gold exploration project in the Coro area of central Rio Muni.
On November 3rd  2006, a new Mining Law for Equatorial Guinea came into effect. Copies of the Law 9/ 2006 in Spanish (original - 2.1 mb  and English (translation - 136 kb) are available for download as PDF files.

MINERALS OPPORTUNITIES

Gold

The rivers of Rio Muni are worked by local artisans using simple panning and wooden sluice technologies. Previous commercial investigations have concentrated on the three main areas of artisanal workings - Coro, Aconibe, and Mongomo and there are several other known occurrences that have been worked. Historical records are incomplete, but at least 2300 kg (74,000 0z) of gold was produced from the Coro area alone in the mid-70's.
The alluvial gold is relatively coarse grained, occurring as either dendritic or rounded nuggets, mostly in the 350-180um size range, although larger nuggets up to 4mm x 8 mm are relatively common. The common occurrence of the gold with vein-quartz, clays, and lateritic minerals attests to the proximity and variable types of bedrock gold mineralisation which have yet to be delineated.

Diamonds 

Heavy-mineral sampling results have identified zinc-rich chromites in the Nsork area, similar to those found in the diamondiferous lamproite dyke swarm at Mitzic (Gabon), 50km to the southeast. Remote sensing and limited outcrop mapping show the dyke swarm trending into the southeastern corner of Rio Muni. Furthermore, exploration in Gabon for both gold and diamonds has identified trails of indicator minerals and diamond right up to the southern borders of Rio Muni. Detailed exploration work is required in the Nsork area to establish the primary sources of the diamonds.

Columbo-tantalite

Mineralisation has been defined in the Aconibe and Ayamiken areas by Nb and Ta soil anomalies and by the presence of heavy minerals commonly associated with Nb-Ta-bearing pegmatites. Neither area has been explored in great detail and thus they represent early stage exploration prospects for pegmatites and skarn systems associated with PanAfrican granitic intrusions. The Aconibe occurrence comprises discrete, laterally extensive pegmatites that are also overlain by eluvial and alluvial deposits yielding grades of 3.0 to 7.5kg/m3. Sample assays have demonstrated niobium-rich columbo-tantalite (62.36% Nb205) with subordinate tantalum (18.74% Ta205).

Other mineral potential 

Widespread lateritisation and indications of bauxitic laterite, with grades up to 58.3% Al203, and 2.1 % to 5.3% SiO2, indicate some potential for bauxite. Anomalous values of base metals, U, As, Ag, Mn and Mo have been detected in laterite above black shales in the Noya Series which is part of the West Congolian foreland basin. This has known base metal deposits immediately to the south in Gabon, and is also equivalent in age to the Katangan sequences of the Democratic Republic of Congo and Zambia. Basic intrusives have been mapped in southern Rio Muni, that may be a northern extension of the Kinguélé ultrabasics trend of northern Gabon, which contains known Ni-PGE mineralisation. Serpentinised ultramafics in central Rio Muni are as yet untested exploration prospects with some potential for base metals and platinoid elements.


Gold in Equatorial Guinea

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Oil and Natural Gas

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Oil &Gas Exploration - overview:
Equatorial Guinea is situated on the oil rich Gulf of Guinea and comprises the Rio Muni coastal enclave, the island of Bioko and the islands of Annobon, Corisco, Elobey Grande and Elobey Chico. The upstream oil industry is key to the economy of Equatorial Guinea and is growing rapidly with expanding foreign interest and investment. Equatorial Guinea’s economy has grown since it started exporting oil in 1995, with oil accounting for 60% of GDP and 90% of total exports. Equatorial Guinea’s natural gas production continues to increase.
According to the 2011 BP Statistical Energy Survey, Equatorial Guinea had proved oil reserves of 1.705 billion barrels at the end of 2010, equivalent to 17 years of current production and 0.12 % of the world's reserves. The survey states that Equatorial Guinea produced an average of 273.9 thousand barrels of crude oil per day in 2010, 0.34% of the world and a change of -10.8 % compared to 2009
The offshore area of Equatorial Guinea falls into two separate sections; the shelf around Bioko Island and the Shelf off Rio Muni, an enclave between Cameroon and Gabon. Both have good hydrocarbon potential.
Although oil was first discovered in the 1960’s, it was first produced offshore in 1991 from the Alba oilfied discovered by Mobil. Production of liquified natural gas (LNG) began in 1997, using wet gas from Alba field. In March 1995, Zafiro field was discovered in Block B with an eventual production rate of 100,000 bpd. Zafiro oilfield is Equatorial Guinea’s major oil producer. Additional discoveries were made on Block B, including Jade, Topacio, Amatista, Rubi and Serpentina. In 1999, a deepwater field, La Ceiba with estimated reserves as high as 300 to 500 million barrels was discovered by Triton Energy and Energy Africa in Block G of the Rio Muni Basin. In mid 2000, Chevron and Vanco Energy signed production sharing contracts for the deepwater Block L and Corisco Block respectively.
Equatorial Guinea’s possessions in the Gulf of Guinea provide it with complex maritime boundaries and territorial delineations. Since mid 1999 there have been strained regional relations over maritime boundaries. Particularly at issue is the Zafiro field in Block B, with Nigeria claiming that it is part of the same structure as the Ekanga oilfield which was discovered by Elf in Nigeria’s concession block OML 102, just 3.5 kilometres north of Block B.
Recently President Obiang unilaterally adopted an equidistant median line defining territorial boundaries as stipulated under the U.N. Convention on the Law of the Sea in March 1999; Cameroon, Sao Tome & Principe, and Nigeria accepted the decision as an improvement over oft-disputed traditional boundaries. Equatorial Guinea and Gabon have disputed the ownership of three islands in the Gulf of Guinea, including Mbagne Island, since the 1970s. In July 2004, the two countries reached an agreement allowing joint oil exploration in the disputed territories until a final resolution is worked out under U.N. mediation.
The Government’s Ministry of Mines and Hydrocarbons regulates the industry and is the licensing authority. Originally the state was represented in an operating company called Guinea-Espanola de Petreleos SA (GEPSA), a 50/50 joint venture between it and Spain’s Hispanica de Petroleos (Hispanoil, now Repsol). GEPSA was subsequently dissolved and there is now no fully owned national oil company in Equatorial Guinea.
The Zafiro field is Equatorial Guinea's largest oil producer, with output rising from an initial level of 7,000 bbl/d in August 1996 to approximately 280,000 bbl/d by 2004. Ceiba, Equatorial Guinea's second major producing oil field, is located just offshore of Rio Muni and is estimated to contain 300 million barrels of oil. Production at Ceiba rose dramatically during the 2-3 year period following improvements and upgrades to the facility. Alba, Equatorial Guinea's third significant field, was discovered in 1991. Original estimates of reserves at Alba were around 68 million barrels of oil equivalent (BOE), but later exploration increased estimates significantly to almost 1 billion BOE. Unlike the Zafiro or Ceiba fields, exploration and production at Alba has focused on natural gas, including condensates. Ceiba's discovery significantly increased interest in petroleum exploration of surrounding areas, with many new companies acquiring licenses in exploration blocks further offshore in the Rio Muni basin. International companies with interests in one or more exploration blocks include Chevron (U.S.), Vanco Energy (U.S.), Atlas Petroleum International (U.S.), Roc Oil (Australia), Petronas (Malaysia), Sasol Petroleum (South Africa), and Glencore (Switzerland). In October 2004, Noble Energy Equatorial Guinea, an Equatoguinean subsidiary of American Noble Energy, Inc. signed a contract to exploit a new oil field off the island of Bioko. Recently, Equatorial Guinea gave the Chinese National Offshore Oil Company (CNOOC) the rights to a new oil field, but Chinese exploration has to date been unsuccessful.
Equatorial Guinea's natural gas reserves are located offshore Bioko Island, primarily in the Alba and Zafiro oil and gas fields. Natural gas and condensate production in Equatorial Guinea expanded rapidly in the 5-year period following new investments by major stakeholders in the Alba natural gas field. Alba, the country's largest natural gas field, contains 1.3 trillion cubic feet (Tcf) of proven reserves, with probable reserves estimated at 4.4 Tcf or more. Marathon Oil, other investors, and the state-owned gas company, SONAGAS, joined together in a $1.5 billion deal to construct a liquefied natural gas (LNG) facility on Bioko Island. The world-class facility shipped its first product in May 2007. In early 2008 Marathon and the government announced tentative plans to construct and operate LNG trains 2 and 3, pending confirmation of feedstock gas from national and neighbouring gas fields.
Source: http://www.state.gov/r/pa/ei/bgn/7221.htm
EXPLORATION HISTORY

License blocks were first designated by the Spanish administration and offered for international tender in 1965 with awards going to groups operated by Mobil and Spanish Gulf Oil (Spangoc) but the exploration effort led to no commercial success. After independence in 1968, petroleum activity was much reduced and further significant exploration did not occur until after the 1979 change of Government. Hispanoil and the new Government formed a joint venture company, GEPSA, which discovered the Alba gas condensate accumulation in 1983. GEPSA deemed Alba to be non-commercial and their licenses lapsed. During the 1980's, Total and Elf operated groups that explored onshore and offshore Rio Muni where extensive seismic surveys were undertaken and four wells drilled without success.
The Alba acreage was relicensed in 1990 to US independent Walter International who commenced production in 1991 from two new wells. In 1995 Nomeco (subsequently CMS Oil and Gas) acquired Walter and progressively expanded onshore processing capacity to cope with increased production from additional Alba wells. The success of the Estrella-1 well (CMS, 2001), a gas condensate discovery 6 km north of the Alba Field, emphasised the large potential of the Alba Block. All CMS assets were acquired by Marathon Oil in January 2002 and Marathon has continued with investment and expansion of the Alba Field.
In 1992, United Meridian Corporation (UMC, subsequently Ocean Energy / Devon Energy) licensed Blocks A and B and in 1995 licensed Blocks C and D. UMC drilled the unsuccessful Dorado-1 well in Block A and the Delta-1 well in Block B in 1994. In 1995 Mobil farmed-in to Block B and drilled the Zafiro-1 discovery well of the 1.1 billion barrel Zafiro Field. Mobil drilled nine exploration wells in Block B outside of the Zafiro area, with discoveries at Azurita-1 (1997), Berilo-1 (1998), Turmelina-1 (1998) and Esmerelda (2005). Mobil aso farmed-in to Block C in 1999 and drilled the Ostra-1 exploration well, followed by the Oreja Marina-1 exploration well in 2001 and Estrella del Mar-1 in 2002.
During 2000, Ocean Energy relinquished Block A and operatorship of Block D was taken over by CMS (now Marathon). In 2004, Marathon drilled the Corona-1 discovery well in Block D which extended the Alba Field into Block D.
Triton Energy was awarded Rio Muni Blocks F & G in 1997, covering areas previously licensed to Elf and acquired seismic through 1997 and 1998. In late 1999 Triton made a significant discovery with the first well on its licences, Ceiba-1, which tested oil at 12,400 bopd and led to the first production in the Rio Muni basin in November 2000. As a result of the Ceiba discovery, an aggressive exploration programme was undertaken by Triton during 2000 - 2001 that continued after the acquisition of Triton by Amerada Hess in 2001. This exploration campaign resulted in 18 successful wells which proved up several hundred million barrels of oil in northern Block G which were developed as the 'Okume Complex'. The Okume Plan of Development was approved by the MMIE in 2003 and the field came onstream in 2006. Additionally the G-13 discovery was made in southern Block G in late 2002 which was appraised in 2003 but remains undeveloped.
Following a Deep Water Licensing Round in 1998-99, five exploration licenses were signed during 2000 with Atlas Petroleum (Blocks H, I and J), Vanco (Block K) and Chevron (Block L) as operators. Extensive 3D surveys were acquired in these licenses in 2001 and exploratory drilling commenced in early 2003 with the drilling of the unsuccessful L-1 well by Chevron. In 2000 RocOil farmed-in to the Atlas Block H and became Technical Operator. This was followed in 2004 by the farm-in of Pioneer and the drilling of the unsuccessful H-1 well. In 2011 White Rose farmed-in to Block H and took over as Technical operator from Roc Oil. The H-2 exploration well is planned for Q4 2012.
In 2004, Nexen farmed-in to Block K, assumed operatorship and drilled the K-1 well in late 2004 followed by the K-2 well in 2005. In 2005 Petrobras farmed in to Block L and drilled the unsuccessful L-2 exploration well and in 2006 both Chevron and Petrobras withdrew from Equatorial Guinea and Block L was relinquished.
During 2002 new exploration licenses were awarded to the Fruitex Group covering Block M in the western offshore Rio Muni and to a Petronas operated group for Block N covering Corisco Bay. Fruitex acquired 2D and 3D in Block M and in late 2003 Petronas drilled the N-1 well (with non-commercial oil) and the N-2 well in 2005.
In 2003, Devon Energy were awarded Block P in the Rio Muni Basin and in 2004 Noble Energy were awarded Block O and PetroSA Block Q, both in the Douala Basin, offshore Bioko Island. In 2004 Devon Energy drilled the unsuccessful P-1 well but in October 2005 the P-2 well was announced as an oil discovery and was subsequently successfully appraised. In 2008 GEPetrol became operator of Block P when they purchased the Devon Equatorial Guinea assets.
In October 2005 Noble Energy announced that the O-1 well in Block O was a gas condensate discovery, the first discovery in the Equatorial Guinea part of the Douala Basin. The O-1 discovery was appraised by the O-3 and I-4 wells in 2007 and declared a commercial discovery, the Alen Field. The Alen Field Plan of Development was approved in January 2011 and production is anticipated to commence in 2013. In February 2009 Noble Energy announced that the O-5 (Carmen) exploration well was an oil discovery, the first oil discovery in Block O. It is anticipated that this will be developed as a tie-in to the Alen facilities.
In 2004 Noble Energy farmed-in to Block I and took over as Technical Operator and in June 2007 announced that the I-1 exploration well was a gas condensate discovery. In October 2007 Noble announced that the I-2 appraisal well to the I-1 discovery, had encountered oil below the gas condensate found in the I-1 well and in June 2008 announced that the I-5 well had confirmed the downdip extent of the oil leg. In July 2009, the Ministry approved the Aseng Plan of Development and first oil from the Aseng Field was produced in November 2011. In November 2007 Noble announced that the I-3 (Yolanda) exploration well was a dry gas discovery and in July 2008 announced that the I-6 (Diega) exploration well was another oil discovery in Block I. In December 2006 Santa Isabel Petroleum Company Ltd, a subsidiary of the China National Petroleum Corporation (CNPC) farmed-in and took over operatorship of Block M. In 2011 Santa Isabel withdrew from Block M and Fruitex resumed as operator.
In May 2006 the Ministry announced that two new PSCs had been signed. Block R, offshore Bioko Island was awarded to Ophir Energy and Block S, offshore Rio Muni was awarded to the China National Offshore Oil Corporation (CNOOC).
In 2007 ExxonMobil drilled the Langosta-1 gas condensate discovery in Block C and in May 2009 Repsol Exploration Guinea SA became the operator of Block C, following the withdrawal of ExxonMobil and SK Coporation from the licence. In January 2009 Ophir Energy announced that the R-2 and R-3 exploration wells in Block R were gas discoveries and in October 2011 the Block R PSC was amended to include unlicensed acreage north-west of the original contract area. In return for the expansion of the acreage, Ophir has committed to accelerate exploration activity in the enlarged area through the drilling of 2 further commitment wells. These wells will form part of a proposed 3-4 well drilling programme which is planned to commence in 1H 2012.
In July 2009 a new PSC for Block X, in the Douala Basin, offshore Bioko Island was awarded to Starc Limited (operator) and Glencore Exploration (GE) Limited.
In early 2010 PetroSA drilled the Q-1 exploration well and in late 2010 acquired additional 3D seismic in Block Q. Also in January - April 2010 CNOOC drilled the unsuccessful S-1 and S-2 exploration wells in Block S.
In July 2010 two new PSCs were awarded to Gazprom Neft, Block T, offshore Bioko Island and Block U, offshore Rio Muni. Gazprom Neft will carry out geophysical and geological evaluation of the existing data and will drill at least one well in each block. Also in July 2010 new PSCs were awarded to Vanco Corisco Deep Ltd over Block K, offshore Rio Muni and Afex Global were awarded Block V, offshore Bioko Island. In September 2011 Glencore farmed-in to Block V and took over as operator.
In March 2011 a new PSC was awarded to Marathon Oil and SK Innovation Co., Ltd over Block D, offshore Bioko Island. In November 2011 Noble Energy announced that the Alen 1-G1 Pilot Well had encountered hydrocarbons in the Carla Prospect, Block O, Offshore Bioko Island, Equatorial Guinea. The Alen 1-G1 Pilot, designed as a gas injector well in the Alen Field Development, was deepened as a pilot hole to target the Carla Prospect which underlies the Alen Field, and encountered approximately 9.9 meters of net oil pay in the objective interval. The operator of Block O, Noble Energy, estimates that the discovered gross resources range between 35 and 100 million barrel oil equivalent of which 80 percent is liquids. Recent appraisal work at Diega, a 2008 discovery in Block I, has confirmed a gross resource range of 45 - 110 MMBoe with 60 percent liquids. Noble Energy anticipates developing both Carla and Diega through the infrastructure at Aseng. Both discoveries are expected to contribute production in 2015.

Equatorial Guinea has experienced rapid economic growth due to the discovery of large offshore oil reserves, and has become Sub-Saharan Africa’s third largest oil exporter after Nigeria and Angola. According to the World Bank, oil revenues increased in value from $3 million in 1993 to $190 million in 2000 to $3.3 billion in 2006. From 2002 to 2006 the country experienced an average real annual GDP growth of 15.8 percent. Oil exports currently represent over 90 percent of total export earnings. However, a slowdown in oil production has caused GDP growth to decelerate to 6.8 percent in 2007.
According to the Oil and Gas Journal, Equatorial Guinea had estimated proved oil reserves of 1.1 billion barrels as of January 2007. The majority of these reserves are located offshore in the oil-rich Gulf of Guinea. Since the 1995 discovery of the Zafiro field, Equatorial Guinea's oil production has increased dramatically. In 1995, oil production was 5,000 barrels per day (bbl/d), which increased to 385,970 b/d in 2006.
The Ministry of Mines, Industry and Energy is the overall regulatory body for the petroleum industry in Equatorial Guinea. The Equatoguinean government created a national oil company (GEPetrol) that became operational in 2002. GEPetrol’s primary focus is to manage the interest stakes of the Equatoguinean government in various production sharing contracts (PSAs) and joint ventures (JVs) with foreign oil companies. The company can also participate in oil exploration and production activities outside Equatorial Guinea.

  • Oil production: 420,000 bbl/day (2005 est.)
  • Oil proved reserves: 563.5 million bbl (1 January 2002)
  • Natural gas production: 100 million cu m (2004 est.)
  • Natural gas proved reserves: 36.81 billion cu m (1 January 2005 est.)
  • In 1995, ExxonMobil and Ocean Energy discovered the Zafiro field, which is located northwest of Bioko Island. Zafiro was the first deepwater field to be brought on stream in West Africa and is currently the main producing field in Equatorial Guinea. Zafiro is currently operated by an ExxonMobil-led consortium that includes Devon Louisiana and GEPetrol. According to the Energy Intelligence Group (EIG) the field contains estimated recoverable reserves of over 400 million barrels, and is Equatorial Guinea's largest oil producer, with an output of 245,000 bbl/d for the first half of 2006.
    Zafiro, as of 2005, has been blended with Topacio and marketed as “New Zafiro”, a low-sulfur distillate rich crude oil. Zafiro was traditionally sold across the US, Europe and Asia-Pacific markets, but recently China has emerged as its single most important purchaser, buying over half its export volumes.
  • Alba, Equatorial Guinea's third largest field is located 12 miles north of Bioko Island. According to the EIG, Alba is a major condensate field containing an estimated 400 million barrels of liquids. The field currently produces between 65,000 and 75,000 bbl/d of condensates and 20,000 bbl/d of liquefied petroleum gas (LPG). Marathon Oil Corporation serves as operator of Alba field along with GEPetrol.
  • Additional production could come from( Amerada) Hess Corporation’s Northern Block G field, expected to come on stream at the end of 2007. According to EIG, initial production is expected to be around 60,000 bbl/d.
  • In 2005, the Equatoguinean government planned to begin a new licensing round for offshore acreage, including parts of Blocks F, G, H and L in the Rio Muni Basin. After several delays, the licensing round went ahead in September 2007. Blocks were awarded to India’s Oil and Natural Gas Corporation Ltd, the Nigerian National Petroleum Corporation, and other independent producers. Prior to the licensing round, PetroSA, the South African state oil company was allocated three blocks for the country’s role in preventing a coup attempt against the government of Equatorial Guinea in 2004.
  • Asian firms from China, India and the Philippines are especially interested in gaining exploration rights. In February 2006, the China National Offshore Oil Company (CNOOC) signed a production sharing agreement (PSA) for offshore acreage in Equatoguinean waters. Under the contract, CNOOC and GEPetrol will have the rights to explore the acreage over the next five years.
  • Tullow Oil holds interests in two production licences offshore Equatorial Guinea, covering the Ceiba field and the Okume Complex. An extension is currently being negotiated on a third licence, which covers exploration Block L, to allow completion of the required regional studies prior to commiting to a well in the next exploration period2006 average gross production from the Ceiba field (Tullow 14.25%) was 40,000 bopd. This was maintained by a successful infill and water injection programme to re-pressurise the reservoir. Infill drilling will continue in 2007 and production is expected to remain around 2006 levels throughout 2007. Production from the Hess operated Okume Complex development (Tullow 14.25%) commenced, ahead of schedule, on 14 December 2006. By early March 2007 the field was producing at 20,000 bopd from 5 wells. This figure will steadily increase during 2007 as more wells are brought on stream. Peak production of 60,000 bopd, is expected to be achieved in mid-2008. The project involves the integrated development of the Okume, Oveng, Ebano and Elon oil fields, collectively known as the Okume Complex. The development includes two tension leg platforms (TLPs), four fixed platforms, and the drilling of over 40 wells. Production from the fields is gathered at a central processing facility (CPF) located at the shallow water Elon field. A 24 km pipeline connects the CPF to the Sendje Ceiba FPSO vessel, which has a storage capacity of 2.1 million barrels, and currently handles production from the nearby Ceiba field.
Source: Tullow Oil
GEOLOGY OF THE RIO MUNI BASIN
The Rio Muni Basin forms part of the extensive West African margin basin system, formed during continental separation and creation of the South Atlantic Ocean through the Cretaceous and Tertiary. This basin system contains a thick wedge of Cretaceous to Tertiary sediments built over an early Cretaceous rifted terrane.
In the Northern Gabon Basin and extending into southern Rio Muni, the rift section comprises lacustrine and fluvio-deltaic faulted and tilted strata of Barremian and Neocomian age. In Gabon this section includes proven sandstone reservoirs, and the Kissenda and Melania lacustrine shales which are prolific source rock intervals. Overlying the syn-rift section is a thick section of Late Aptian salt and a well developed succession of Mid to Late Cretaceous and Early Tertiary marine limestone and sand-shale sequences. Movement of salt has formed a wide range of prospective traps including diapirs, turtle-backs, and rollover structures to growth faults on the margins of salt walls.
In northern Rio Muni, the syn-rift section comprises Late Barremian to Mid Aptian terrestrial clastics and lacustrine shales characterised by extensional rollover structures to mega-scale listric faults updip, and toe-thrust structures downdip. The syn-rift section is overlain by a “transitional” sequence of well-developed salt and good quality marine oil-prone source rock intervals. An Albian (Madiela) carbonate platform developed over the area plus a Cenomanian-Turonian sand-shale sequence which contains a major source interval. This post-salt sequence commonly forms extensional rafts detaching on an Albian-Aptian shale or salt. A well developed Senonian section onlaps the earlier rafted topography. The latest drift sequence is dominated by a thick wedge of Miocene to Recent clastics.
Modelling indicates that the “transitional” source intervals may be locally mature on the shelf and may have charged Albian to Turonian carbonates and clastics. The deep water equivalents are believed to have been generating hydrocarbons from Mid Tertiary times and provide the likely source to the deep water sandstones which provide the excellent reservoirs encountered at Ceiba.

GEOLOGY OF OFFSHORE BIOKO
Offshore Bioko contains an active petroleum system comprising reservoir sands that lie structurally above voluminous marine shales containing oil-prone source rocks. The most important of these are the marine shales of the basal Pliocene Qua-Iboe and the Miocene Akata (Isongo) Formations which contain mixed Type II and Type III .
A thick sequence of Tertiary to Quaternary sands and shales was deposited as a wedge of clastic sediments in the distal Niger Delta basin setting. Shelf edge sedimentation has led to deposition of delta slope and basinal clastics by a variety of gravity driven processes including gravity sliding, debris flow and turbidity currents. Progradation of the delta has been accompanied by shale diapirism and growth faulting with associated rollover structures, and a zone of compressional toe-thrusting has developed at the foot of the delta slope.
The reservoirs at the Zafiro field complex occur in debris flow and slump sandstones of the Qua-Iboe Formation, comprising large, channelised sandbodies deposited in deep water settings. The Alba field produces from a deep water sand in the Isongo Formation.
Simple four-way dip structural closures and toe-thrust structures are common within the Isongo Formation whereas the Qua Iboe Formation contains a number of structurally enhanced stratigraphic traps. Good seals for all traps are provided by the interbedded Qua-Iboe and Isongo shales.
Regional seismic lines show that Mid to Late Cretaceous strata extend far into the ultra-deep water and certainly beneath the present-day volcanic intrusives such as Bioko Island. This is evidenced by the oil seeps on the volcanic trend in Sao Tome and the occurrence of Turonian ammonites on Bioko. The presence of volcanics in this setting therefore need not preclude hydrocarbon occurrences in the vicinity of Bioko and the other islands in the chain, including Annobon.
Exploration is at an immature stage in offshore Bioko and holds considerable potential for future discoveries. The deep water areas to the south and west of Bioko hold potential, particularly within large fan-like mound features recognised on seismic data in front of the toe-thrust limit, which are as yet untested by drilling.

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Posted by Carel van der Merwe at 13.4.07