Mr. Don Riaroh Director E&P Ministry of Energy Kenya

1. Petroleum Geology and Exploration Opportunities in Kenya11th Africa Conference for Oil and Gas Kenyatta International Conference Centre, Nairobi, - Kenya, (23rd – 25th May, 2007) Mr. Don Riaroh Director E&P Ministry of Energy Kenya NOT AN OFFICIAL UNCTAD RECORD

2. Contents • 1. Introduction • 2. Past Exploration Activity • 3. Why Past Petroleum Exploration Activity Failed • 4. Petroleum Geology & Exploration Activity • 5. Conclusion 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

3. Introduction • The first Exploration Licence issued to d’Arcy in 1937 in Lamu Embayment near Mombasa in Kenya. • Active Oil exploration in Kenya commenced in 1954 when Oil Exploration License (OEL1) was granted to B. P Shell Development Company to operate in Lamu Embayment. • Initial Exploration (1950’s – 1980’s) concentrated in the Lamu Embayment. Interest later expressed in other areas, Anza 1975-1990, Tertiary Rift 1990, offshore (I) 1978-1985, offshore (II) 2003-present 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

4. Introduction Sedimentary Basins of Kenya • Kenya has four major sedimentary Basins with approximate total area of 400,000 sq. km. These are: • Anza Basin ~ 82,000 sq km • Lamu Basin ~ 170,000 sq. km • Mandera Basin ~ 44,000 sq km • Tertiary Rift ~ 105,000 sq km 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

5. Past Exploration Activity 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

6. Past Exploration Activity No. of Wells = 31 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

7. Past Exploration Activity Seismic Coverage Map 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

8. Past Exploration Activity Total Seismic Coverage = 85,617 km 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

9. Past Exploration Activity Past Air-Mag Surveys 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

10. Past Exploration Activity Total Air-Mag Coverage = 148,099 km 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

11. Why Past Exploration Efforts Failed • Many wells drilled were shallow stratigraphic tests, which did not fully evaluate the prospects /targets e.g (Walu-1, Pandangua-1 and Meri-1, in 1959- 60, and Mararani-1 in 1961) • Many wells were drilled using poor quality seismic data eg Walu-2 (1963) and Wal Merer-1 (1966) • Many wells were poorly sited and or drilled on poorly defined structures • Some wells were drilled without geological and geophysical justification e.g Ria Kalui Well • Premature abandonment eg Simba-1 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

12. Why Past Exploration Effort Failed Many wells were drilled using poor quality seismic data eg Walu-2 (1963) and Wal Merer-1 (1966) Poor quality seismic data 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

13. Why Past Exploration Effort Failed Many wells were drilled on poorly defined structures Most of the Anza Wells do not show full closure Time Structure Map - Top Cretaceous 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

14. Why Past Exploration Effort Failed Poorly sited well Time Structure Map - Top Cretaceous 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

15. Why Past Exploration Effort Failed Kaisut Well located off the Crest 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

16. Why Past Exploration Effort Failed No defined Trap 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

17. CENTRAL AFRICAN RIFT SYSTEM 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

18. Petroleum Geology and Exploration Opportunities • Anza Graben • The Anza Graben is part of the Central Africa Fault system • trends northwest- southeast and extends across much of eastern and northern Kenya. • The Basin consists of three sub-basins: the South Anza, North Anza, and North Anza Extension. • The total surface area of the entire Anza Basin is approximately 94,220 sq km. • Much of the South Anza Basin is separated from the Mandera Basin by the extensive Lagh Bogal fault and from the Lamu Embayment by the Muchesa Highborder fault. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

19. Petroleum Geology and Exploration Opportunities • Anza Graben Contd.. • Contains Late Jurassic to Mid-Cretaceous fluvial-Lacustrine sediments analogous to the Abu-Gabra Rift Basin where oil production has been established. The Anza wells, however, may never have penetrated deeply enough to test the equivalent Neocomian to Lower Albian section which comprises the source and reservoir units of the Unity and Heglig fields of Sudan. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

20. Petroleum Geology and Exploration Opportunities Anza Graben Contd.. • Reservoirs – • Target reservoirs occur throughout the stratigraphic section. Reservoir objectives in the South Anza Basin include continental deposits of the Karroo; Tertiary fluvial, deltaic, and occasional lacustrine sandstones; and Lower Jurassic carbonates. Continental fluvial and lacustrine sandstones (Cretaceous through Tertiary) comprise the potential reservoir units of the North Anza Basin. In addition, Neocomian Nubian continental sandstones are postulated to occur in the North Anza Basin Extension. • Seals – • Most reservoirs in the South Anza Basin are overlain by regional, transgressive marine shales. In the northern portions of the Anza Basin, evaporites (Jurassic), as well as interbedded shales and volcanics (Cretaceous through Tertiary), should provide very effective seals for the reservoirs in these areas. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

21. Petroleum Geology and Exploration Opportunities Anza Graben Contd.. • Source Rocks – • The most favorable source rocks throughout the entire Anza Basin are Neocomian through Lower Albian shales. Similar potential exists within the Lower Tertiary Paleogene. • Trapping Configurations – • Structural traps have been observed in sections ranging from Karroo through Tertiary. Tilted fault blocks, horsts, and large rollover structures (related to listric faults) are common. There is also potential for untested, wrench-related structures in the South Anza Basin. In addition, stratigraphic traps may exist in the southern basinal areas where interbedded sequences of lacustrine sandstones and shales provide a very effective reservoir, source, and seal. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

22. Petroleum Geology and Exploration Opportunities Seismic Section Across Anza 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

23. Petroleum Geology and Exploration Opportunities Lamu Embayment • This is Kenya's largest basin with an area of 170,000 sq. km • encompasses depocenters located in both onshore and offshore southeast Kenya • Although the Lamu Embayment has a long history of onshore exploration, recent efforts have been limited. The last well drilled was the Petro-Canada KenCan Well (1986). • Although production has not been established in the Lamu Embayment, hydrocarbon potential has been indicated by cuttings, fluorescence and shows of gas in wells penetrating Cretaceous through Tertiary sections. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

24. Petroleum Geology and Exploration Opportunities Evolution of Lamu Embayment Lamu Embayment • Continental sag, Karoo rifting ≥ 400km of continental deposits • Minor marine incursions • Break-up Gondwanaland & drifting of Madagascar in upper Jurrassic giving rise to Major marine transgression and Deposition of deep/distal marine sediments • Drifting of Madagascar, India & Antarctica continued until Aptian times creating the Davy Fracture Zone • Marine sedimentation continued along E. Africa Coast • Albian, Aptian limestones are observed in Hargaso – 1, Wal-Merer – 1 wells. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

25. Petroleum Geology and Exploration Opportunities Lamu Embayment Evolution Contd.. • Tertiary sedimentation controlled by the Davy Fracture Zone (DFZ) • The DFZ Divides offshore Lamu into two parts. • Northern section reduced sedimentation showing gravity sliding and mass movement structures • Southern section which show extensional basins which have undergone extension 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

26. Petroleum Geology and Exploration Opportunities Off-Shore Lamu Embayment Contd.. • Source • Hydrocarbon seeps in Pemba Island • Late Cretaceous black shales DSDP 241 • Onshore evidence exists for the presence of potential source rocks in Lower Tertiary marine shales. Maturity of the known shale units may be suggested by oil and gas shows present in the Kipini and Dodori wells. In addition, significant quantities of gas were measured in the Pate Well while drilling through Lower Eocene sandstones. • Other possible source rocks include units within the rift sequence of the Early Jurassic and pre-rift sequences of the Karroo. Jurassic rift sediments, buried to depths of 6,OOOm before the Late Cretaceous uplift, may have generated hydrocarbons which then migrated into Neocomian sand- stones. The possibility of source rocks occurring in marine shales of the Karroo must also be considered. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

27. Petroleum Geology and Exploration Opportunities Off-Shore Lamu Embayment Contd.. • Reservoirs – • Drilling and outcrop studies have confirmed the presence of potential reservoirs which range in age from the Permian to the Neogene. Karroo continental sequences (as observed in outcrop) include Mazeras sandstones, Carbonates such as the Jurassic Kambe Limestone (oolitic), Cretaceous Freretown Limestone, and Tertiary carbonate build-ups. The best reservoir potential likely remains in Tertiary progradational sandstones. • Reservoir • Simba-1, Pomboo-1- encountered upper crateceous – paleocene turbidite sands • Kofia -1, Kipini wells Eocene-Upper cretaceous Blockly argillaceous and calcareous sandstone (Φ 15 to 25%) • Seal – Pomboo has encountered thick shale sequences - Other seal facies could include evaporite sequences 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

28. Petroleum Geology and Exploration Opportunities Off-Shore Lamu Embayment Contd.. • Trapping Configurations – • Four way structural traps – • Simba, Pomboo,Tumbusi etc formed by sediment flow flow • Fault bounded structural closures along the Davy-Walu high • Prevalent trapping configurations include block-faulted anticlinal structures with associated antithetic faults. These structures are related to tension and compaction on the continental margin. • Seismic sections reveal that radially arranged fault traps over the crests of salt structures are common along the near-shore areas of the coast. • Potential leads for stratigraphic trapping have been observed where pinch-outs of the Tertiary sandstones onto the Cretaceous, or the Cretaceous onto the Jurassic, have occurred (on the flanks of the Garissa High, for example). 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

29. Petroleum Geology and Exploration Opportunities Seismic Section Across Lamu 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

30. Petroleum Geology and Exploration Opportunities Prospect in off-shore Lamu 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

31. Petroleum Geology & Exploration Opportunities Mandera Basin • The Mandera Basin is a broad basin which extends into Kenya, Ethiopia, and Somalia. The western flank of the Mandera Basin is located in northeast Kenya and covers approximately 51,920 sq km 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

32. Petroleum Geology and Exploration Opportunities Mandera Basin • The Basin is filled with up to 8,0OO -10,000m of Karroo & post-Karroo fluvial-continental, lacustrine, and marine sediments. • Carboniferous rifting initiated the development of the Mandera Basin and the Lamu Embayment • From the Middle to Late Jurassic, the Mandera Basin developed as a slowly subsiding platform basin. • The Kenyan portion of the Mandera Basin is relatively unexplored. Only two stratigraphic wells Elgal I & II have been drilled (1987) in the basin. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

33. Petroleum Geology and Exploration Opportunities Evolution of the Mandera Basin 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

34. Petroleum Geology and Exploration Opportunities Geology of the Mandera Basin 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

35. Petroleum Geology and Exploration Opportunities Stratigraphy of the Mandera-Ogaden Basin 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

36. Petroleum Geology and Exploration Opportunities Mandera Basin Contd.. • Source Rocks • The presence of the Tarbaj Hill oil seep (possibly charged from a mature Jurassic marine sequence within the basin), as well as oil shows in the Burmah Hol-1 Well of the Somali Mandera Basin, strongly suggest untapped hydrocarbon potential in this area. • Analysis of the Tarbaj Hill oil seep indicates the presence of mature marine source rock. The source for this oil is interpreted to be either the rift sequence of the Karroo (equivalent of the Maji-ya-Chumvi shales of the Mombasa area) or Lower Jurassic marine shales (located in the deeper, interior part of the basin) 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

37. Petroleum Geology and Exploration Opportunities • Mandera Basin contd.. • Permo- Triassic • Elgal shales – whose equivalent are Bokh Shale formation, that sourced Calub Reservoir in Ethiopia. • Triassic/Low Jurassic • Tarbaj Oil Seep, in Mansa Guda Triassic Formation points to marine source rocks. Related to transgressive Shales that were deposited just below the Didimku limestone interval. • In Ethiopia their equivalent are the Lower Hamanlei that sourced the Adigrat reservoir in Calub/Genale /Galadi wells where heavy to medium oil has been tested. • Jurassic • Deeper sediments could give encouraging results. • The Rhamu shales are equivalent to Uarandab shales in Ethiopia 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

38. Petroleum Geology and Exploration Opportunities Mandera Basin Contd.. • Reservoirs • Karoo clastic formations (grits, sandstones) • Triassic- Lower Jurassic • Coarse grained stream deposits of Mansa Guda sandstones, porosities ranging from 8% to 14%. • Middle to Upper Jurassic • These are the Upper Murri and Rukesa grainstones with porosities between 10 to 20%, their equivalent in Ethiopia are the Hamanlei with porosities ranging from 8 to 10% • Seals • Seals are present at many levels • Elgal shales in Lower Karoo, • Base Liasic shales below Diidimtu limestones • Evaporites in Hamanlei. • Rukesa , Hereri and Rhamu shales Jurrassic 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

39. Petroleum Geology and Exploration Opportunities Mandera Basin Contd.. • Traps • Most play concepts are associated with structural leads e.g Sengif structure, • Golberole Hill fault zone • El-Wak structural lead • Structures related to tilted blocks. • Anticlinal features. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

40. Petroleum Geology and Exploration Opportunities Tertiary Rift Basins • Kenyan Rift is part of the East African system • The main basins of the Kenya Rift are the Turkana, Lokichar (Loperot), Suguta-Magadi, South Kerio, and Nyanza troughs, which cover a total surface area of approximately 105,000 sq km. • Kenya Rift contain sufficient sedimentary fill to form potential mature sources for hydrocarbons. • The northern part of the Kenya Rift, comprising the Suguta, Turkana, and South Kerio troughs, has had most petroleum exploration activity. • Two wells, Loperot-1, Eliye Springs were drilled in the Basin 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

41. Petroleum Geology and Exploration Opportunities Eastern African Basins 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

42. Petroleum Geology and Exploration Opportunities Tertiary Rift Contd.. • Numerous productive analogs of the types of reservoirs expected in the Kenya Rift Basins; include lacustrine sandstones such as those Albertine Graben in Uganda. • The oldest potential reservoirs are the probable Late Jurassic to Mid-Cretaceous fluvial-lacustrine sandstones occurring in the Turkana area. These sediments likely were deposited during the pre-rift to early rift development of the Cretaceous Anza-Abu Gabra rift-type graben, which was crossed by the younger (Late Cretaceous through Recent) north- south trending Turkana Trough. Elsewhere in the western Kenya Rift Basins, Neogene sequences were most likely deposited directly on metamorphic basement.Porous and permeable fluvial-lacustrine sandstones comprise the reservoirs in Neogene Rift Basins (such as the Nyanza and South Kerio troughs). These sandstone units are typically intercalated with siltstones and shales, which may act as both source rock and seal. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

43. Petroleum Geology and Exploration Opportunities Tertiary Rift Contd.. • Seals – • Potential seals exist in the fine- grained lacustrine sediments and compact volcanic sequences. These impermeable units provide intraformational cap rocks for lacustrine reservoirs. • Source Rocks – • Miocene syn-rift sedimentary deposits, particularly the Ngorora Formation (Poi Shale Member), provide excellent lacustrine source rocks (ToC 14%). Despite their young age, these organic-rich units could have undergone favorable maturation because of the high geothernlal gradients present in the Kenya Rift. • Trapping Configurations – • The tectonic style of the Kenya Rift is characterized by block faulting in brittle material, rollover structures in more plastic deposits (Plio- Pleistocene of Turkana). These structures provide good potential for the entrapment of hydrocarbons. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

44. Petroleum Geology and Exploration Opportunities Seismic Section Lokichar-Kerio X-section 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

45. Petroleum Geology and Exploration Opportunities Lobster Structural Leads 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

46. Conclusions • The failure to discover hydrocarbons may therefore be attributed to the selection of the well locations: poor definition of the structures, little knowledge of local conditions, possible facies variations within the reservoirs, relative non mature source- rocks in the Tertiary. • Potential for hydrocarbon entrapment exists in Jurassic carbonate reservoirs charged by a mature, marine sequence in the Jurassic of the Mandera Basin. • Untested potential remains in the Anza through, to the Lotikipi Basins. Probable reservoirs include Lower Cretaceous (Neocomian through Albian) fluvial-lacustrine sediments with intra- formational source, reservoir, and seal potential. The analog for this potential is the productive Abu Gabra Rift Basin of Sudan. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

47. Conclusions Contd.. • There are many remaining opportunities for leads and prospects within the trend of near-shore structures of the Lamu Embayment where crestal, radially arranged fault blocks and favourable trapping configurations have been observed on seismic data. These structures are associated with good quality Tertiary reservoir sandstones. This play concept has never been tested in Kenya. • Stratigraphic trapping configurations also exist within the Lamu Embayment, where amplitude anomalies and pinchouts are commonly observed on seismic data. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

48. Conclusions Contd.. • Recent investigations have led to the up-grading of the South Kerio and Nyanza troughs of the western Kenya Rift Basin to prospective Neogene depocenters with favorable tectonic styles for hydrocarbon entrapment. Miocene, synrift sedimentary deposits, such as the Ngorora Formation, provide excellent lacustrine petroleum source rocks which are likely to be mature because of the high geothermal gradients present in the Kenya Rift. • Welcome to Kenya and we look forward to holding discussions with you on the acreages. 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA

49. Thank you for your Attention !!! 11th UNCTAD Africa Oil & Gas Conference, Nairobi, KENYA