Michael Aryeetey, Lead Geoscientist at GNPC - Unlocking the ultradeepwater potential offshore ghana
Unlocking the HydrocarbonPotential of the Ultra DeepwaterBasins Offshore GhanaWorkshop – Ballroom 2June 4, 2013; 9:00amBy Michael N. A. AryeeteyLead Geoscientist, GNPC
Presentation Outline• Introduction – GNPC• Deepwater /Ultradeepwater Exploration Worldwide• Deepwater /Ultradeepwater Exploration-West African Margin• Sedimentary Basins in Ghana• Deep & Ultra Deepwater Data Coverage• Deepwater Exploration offshore Ghana• Deepwater Exploration – Tano Basin• Deepwater Exploration – Keta Basin• Current Exploration Opportunities• The Petroleum System• The Processes & Schedules• Conclusions
Ghana National Petroleum Corp: GNPC• National Oil Company established in 1983; and givenlegal backing by two main statutes i.e. PNDC Laws 64 and84• Vision: To be a leading global oil and gas company whoseoperations have a profound impact on the quality of life ofthe people of Ghana.• Mandate: 1. To accelerate the promotion of petroleum explorationactivities to ensure early commercial discovery andproduction 2. To undertake the appraisal of existing petroleumdiscoveries to ensure production to meet nationalrequirements3. To ensure that Ghana obtains the greatest possiblebenefits from the development of its petroleum resources4. To obtain the effective transfer to Ghana of appropriatetechnology relating to petroleum operations 5. To ensure the training of citizens of Ghana and the development of national capabilities in allaspects of petroleum operations and; 6. To ensure that petroleum operations are conducted insuch a manner as to prevent adverse effects on theenvironment, resources and people of Ghana.seismicDrilling RigOil TankerSkill TransferProduction Platform3
Deepwater Exploration Worldwide• Over the past 20 years, understanding of deep-water depositionalsystems has progressed rapidly, while major technological advanceshave pushed the frontier for exploration and development of deep-water fields further offshore• Reservoirs deposited in deep water occur worldwide in a variety oftectonic settings, but are particularly common in rift and passive-margin basins. • The total number of deep-water fields so far discovered throughoutthe world number between 400/5005
Deepwater Exploration & Production WorldwideSource: Pettingill (1999)7
Deepwater Exploration Successes Worldwide• Successful exploration in the Miocene of Nigeria, Angola and Brazil• Significant success in the Upper Cretaceous in Ghana, EquatorialGuinea, Liberia, Sierra Leone, Angola etc.• The Upper Cretaceous-Lower Paleocene successes in the North Sea• Growing excitement generated by the Agbami giant in Nigeria, La CeibaField in Rio Muni, Jubilee & TEN Fields in Ghana; more along the WestAfrican Margin8
Why is the West African deepwater so prolific?Simplicity of the play elements which include:1. Regional development of abundance of rich oil prone sourcerocks2. Frequent presence of thick clean sands3. Young structuring4. On-going hydrocarbon generation Oil is invariably generated wherever there is sufficientsedimentary loading for maturity This region now represents one of the most exciting frontierexploration provinces in the world!10
Prospectivity of the West African Margin11Country Discovery OperatorSierra Leone Mercuy AnadarkoJupiter AnadarkoCote d’IvoireEspoir CNR InternationalLion CNR InternationalBaobab CNR InternationalGhanaMahogany Tullow OilOdum KosmosEbony Tullow/InteroilMahagany Deep KosmosTweneboa Tullow OilEnyenra (Owo) Tullow OilTeak KosmosSankofa/GyeNyame ENI/VitolDzata Vanco/LukoilBanda KosmosParadise HessAkasa-1 KosmosNtomme TullowNigeria Udele-3 SinopecPegi ExxonMobilAgge-3B.T1 ConoilCameroun Sapele-1 BowlevenGabon Maroc-Nord (OMOC-N) Maurel & PromSE Etame-1 Valco EnergyAngolaCastanha Plus PetrolNzanza ENICinguvu ENIBegonia TotalCabaca South East ENIMpungi ENICanna-1 Total
Sedimentary Basins - GhanaBasin Age of Sediments Total SizeTano-Cape ThreePointsCretaceous 60,000 sq. km(up to 3,000mWD)Central (Saltpond) PaleozoicAccra-Keta Cretaceous/PaleozoicOnshore Voltaian Precambrian-Paleozoic103,600 sq. km12
Geological Setting13Basin development related to the opening and spreading of the Equatorial Atlantic Ocean anddivergence of the African and South American plates.The basins are wrench-modified with the deepwater part dominated by Upper Cretaceousslope and basin floor fans, channel systems and other stratigraphic traps; and LowerCretaceous tilted and rotated fault blocks (rift section).
Ultra-Deepwater Exploration offshore Ghana14GHANAOFFSHORE 2D & 3D SEISMIC COVERAGE
Current Opportunities – Tano Deep/Ultra DeepwaterDeep/Ultra DeepwaterTHE DEEPWATER TANO BASINCretaceous basin located in the transform margin of WestAfrica. Basin development as a result of rifting and drifting ofthe Atlantic margin. Thick Upper Cretaceous-Tertiary section overly a rift section.The drift section is dominated by slope and basin floor fans,channel systems and other stratigraphic traps.The main source rock are the Turonian-Cenomanian sectionand the Albian shales.The thick drift section provide enough overburden to maturethe source rock and the same time serve as seals for thestratigraphic play types.This is a PROLIFIC deepwater basin that plays host tonumerous oil, gas, and condensate discoveries; eg. Jubilee(Mahogany), Tweneboa, Enyenra, Ntomme, Akasa,Paradise, Sankofa and Dzata.
Ultra Deepwater Tano18• Located in the prolific offshore Tano basin,in close proximity to the Jubilee Field. • Water Depth: 2000 - 3,500 m • Blocks in Basin play host to severalsignificant oil, gas and condensatediscoveries including the Tweneboa-Enyenra-Ntomme (TEN) - Tullow; JubileeField-(Tullow & Co), Mahogany-Teak-Akasa(MTA) - Kosmos; Paradise (Hess); Dzata(Lukoil/Vanco); • High quality 2D and 3D seismic data• Proven Petroleum System • Numerous unexplored Cretaceous PlayTypes
Deepwater Exploration – Keta Basin20Basin 2DseismicDatakm3DSeismicDataSq kmDeepwaterWellsdrilledAccra KetaBasin12,963 2,737 2Tarpon Well (Devon)• The Tarpon well was drilled in 2003 to test a seriesof Miocene fans on the eastern flank of the KetaArch • The well proved excellent Miocene reservoir, (246ft. net sand, av. 31% porosity), had trace amountsof hydrocarbons based on fluid inclusion data.• The primary reason for failure was the lack of arobust migration pathway from the UpperCretaceous hydrocarbon system into the Tertiarysection.Cuda Well (Afren)• Afren drilled the Cuda exploratory well in December2008 to a depth of 12,425 feet. • The contractor had to abandon the operation afterencountering excessive high pressure which posedgreat danger to life and property. • Thus, they could not reach the obligated target anddepthBasin Play Type Drilling DensityAccra Keta(deepwater)Stratigraphic 1 well/2000 sqkm
Current Opportunities – Ultra Deep Keta BasinDeep/Ultra DeepwaterFavorable Conditions•The Volta River creates a unique depositional system along the transformmargin of West Africa in Eastern Ghana that is similar to the Rio Muni Basinin Equatorial Guinea. •A tremendous volume of Upper Cretaceous sands were deposited andexcellent reservoir quality Eocene and Miocene sands were encountered inthe two shelfal wells.•Large volumes of Upper Cretaceous sands were deposited in deep waterfans across the growing structures on the Keta Arch. •There is enough overburden to mature the rich Turonian source; It is in the oilgeneration window.• The Volta River provides 10000 ft thickness Mid-Miocene to Pliocenesediments, that caused late phase of oil generation and migration beginningaround 5 million years ago through to today. •The hydrocarbon migration on the Keta Arch is further supported bynumerous hydrocarbon flags in the shallow section.•Oil and gas seeps and chemosynthetic communities were observed in pistoncores. A large persistent oil slick is identified on satellite images of variousvintages.
Accra-Keta Basin22DiplineStrike LinePINCH-OUT OF DRIFTSEDIMENTSROTATED FAULT BLOCKS – RIFTSEDIMENTS
ChallengesIt relate to all areas of operations including but not limitedto:• Seismic acquisition, • Drilling operations,• Completion operations, • Subsea operations, production operations,• Logistics support;• High Pressures (>10,000psi) & Temperatures (>200°C): HPHT• Deep and tight Reservoirs (<10mD)• Flow Assurance Issues
Others Have Braced The Storm• This challenge has seen an exploration well being drilled in over10,000 ft [3048m] of water and another being drilled in 3,100m inIndia• A subsea production well in the GoM being completed in marginallyless than 10,000ft [3048m] of water. • It is anticipated that being able to commercially develop resources insuch water depths will be fundamental to the continued long termsuccess of ultra deepwater exploration in the world’s major producingbasins. • From a worldwide perspective deepwater developments will accountfor approximately 25% of offshore oil production by 2015, comparedto just 9% at present.25
The Processes & Schedules26Dataroomaccess andsubmission ofproposal toGNPCGNPCEvaluation of allproposalsGNPC invitationto andnegotiations withpreferred partnerGNPC andPartner meetsMOE to discussPAPA approval andratificationJOINT VENTURE MODELG&G DataReview @GNPCApplicationsubmission toMOE with US$10,000ApplicationEvaluation byMOE & GNPC/PCExpression ofInterest to MOE& GNPCRecommendationby GNPC Board toMOE:Decline /Invitation forNegotiationsNegotiationTeamConstituted byMinisterNegotiatedDraft PAinitialed &submitted toMinisterMOE submitsInitialedPA to Cabinetfor ApprovalGNPC Meets SelectCommittee on Energyfrom Parliament for anyclarificationAfter Approval, thento Parliament forconsideration, andratification.PA Ratified;CompanycommencesoperationsNORMAL APPLICATIONPROCESS
GNPC’s Strategy• The strategy for attaining this vision incorporates apreferred alliance model (JOC/JV) with large to mediumsize independent companies• With a Partner who will commit to developing independentoperating capability of GNPC in the medium to long termand/or transfer of operatorship• It will also involve participation in equity investmentthrough innovative risk sharing in alignment with theobjectives of the Corporation.27
Conclusions• The industry is in the busiest period in its recent historyand as we continue to pursue prospects in deeper waterdepths and more challenging reservoirs • The need for technology development and equipmentqualification to meet the corresponding technicalchallenges for project development are becoming muchgreater.