East Africa Transform Margin The View from Tanzania and Madagascar Richard Higgins and Mark Sofield 10 th PESGB/HGS Conference on African E & P, London, September 7-8, 2011 Acknowledgements Legal Notice: No representation or warranty, express or implied, is or will be made in relation to the accuracy or completeness of the information in this presentation and no responsibility or liability is or will be accepted by Ophir Energy Plc, it s joint venture partners or any of its respective subsidiaries, affiliates and associated companies (or by any of their respective officers, employees or agents) in relation to it. 1
Agenda Location & Recent Activity Regional Tectonic Elements Influence on Petroleum System Elements Summary MOZAMBIQUE TANZANIA 2
Recent Activity East Africa Multiple 2D and 3D Seismic surveys acquired since 2005 Drilling campaigns conducted in Tanzania (Ophir/BG) and Mozambique (Anadarko et al.) in 2010/2011 Pweza Gas Discovery Chewa Gas Discovery Chaza Gas Discovery Windjammer Gas Discovery Barquentine Gas Discovery Lagosta Gas Discovery Seven gas discoveries Various farmin/farm outs in Tanzania and Kenya Licence signatures in Kenya Tubarão Gas Discovery Ironclad Oil Shows 3
Recent Discoveries Tanzania Strong relationship between seismic amplitude anomalies and gas-bearing reservoirs. Nearby targets with similar seismic characteristics now substantially de-risked. Further 3D seismic surveys have been acquired and are currently being processed. 4
Regional Tectonics Karroo continental rifting Late Carboniferous to Early Jurassic Gondwanaland break-up Initial opening ~180Ma (NW-SE) N-S opening from 160Ma to 120 Ma Development of passive margin successor basins East African Tertiary Doming 5
Tanzania - Gravity MASAI BASEMENT SPUR EP B4 B3 B1 Seagap Fault Zone Davie Fracture Zone Significant change in gravity signature across the Davie Fracture Zone (DFZ), separating continental and oceanic crust. Continental crust dominated by N-S trending anomalies that appear to step across NE-SW trending lineaments. NE-SW lineaments interpreted to represent Early Jurassic rift faults N-S anomalies possibly represent Cretaceous structures generated during Jurassic to Aptian, coincident with movement along the DFZ. N-S structures reactivated during Oligocene to Recent. 6
Seagap Fault Zone Triassic/Jurassic Rift Faulting Generation of N-S Seagap Fault Zone during Jurassic to Aptian? Reactivation of rift faults? Oligocene onset of reactivation (transtensional in above example) Pliocene reactivation (generates transpressional anticline in above example) 7
Seagap Fault Zone Transtension Transpression 8
Seagap Fault Zone SEMBLANCE A Riedel? A B Restraining Bend B C C D Releasing Bend D Modified from Mikenorton, Wikipedia, 2009 9
Tanzania - Onshore From Nicholas et al., (2007) From Nicholas et al., (2007) 10
Structural Control on Reservoir Input S N East Pande 11
Reservoir Quaternary Holocene Pleistocene Quaternary and Tertiary Tertiary Mesozoic Tertiary and Cretaceous Cretaceous Lower Cretaceous Cretaceous and Jurassic Jurassic Lower Jurassic Jurassic and Triassic Triassic Lower Triassic Mesozoic and Paleozoic Cretaceous through Carboniferous Jurassic through Carboniferous Paleozoic Permian Triassic and Permian Permian-Carboniferous Carboniferous Carboniferous and Devonian Devonian Upper and Middle Devonian Devonian and Silurian Silurian Silurian-Ordivician Ordivician Ordivician-Cambrian Cambrian Precambrian Paleozoic-Precambrian Proterozoic Quaternary extrusive and intrusive Tertiary extrusive and intrusivei Mesozoic extrusive and intrusive Mesozoic-Paleozoic extrusive and intrusive Paleozoic extrusive and intrusive Kimberlite Subsurface salt dome Open Water Bathymetry 0 to 200 200 to 1000 1000 to 2000 2000 to 3000 > 3000 Fault-controlled sediment input Long-lived sediment input from quartz-rich provenance 12
Madagascar - Gravity NE-SW rift faults NW-SE transfer zones Deep structural control on sediment input and fault linkage 13
An East African Deepwater Cretaceous Source Rock? 249 Thin Aptian Shales TOCs up to 9% AFRICA Early Aptian source rocks in Outenqua Basin MB Duvalia Formation (Berriasian to Aptian shallow to deep marine facies) in Southern Morandava Basin potential for an Excellent quality Lower Cret. source rock TOCs average 3.74%, max 26.3%, HI Ave 167, Max 403. Africa NV ANTARCTICA Greater India Alb-Cen-Tur in Northern Morandava Basin potential for oil and gas source rock. TOC 0.8 to 3.4%, HI max 240. 330+511 Barremian-Aptian organic rich shales up to 35m thick TOCs 3 to 16% 692 Valanginian organic rich sediments 45m thick. TOCs up to 18% 693 Aptian organic rich sediments 68m thick. TOCs up to 4% Antarctica India Serinam-1 North Morondava Basin Light oil/wet gas source rock pot. in 15m Lwr Cret (Haut-Barrem). TOC 1.7 to 9.3%, HI max 248. APTIAN RECONSTRUCTION APTIAN RECONSTRUCTION DSDP 330+511 Barremian-Aptian organic rich shales up to 35m thick TOCs 3 to 16% Aptian source rocks in Outeniqua Basin, South Africa. DSDP 249 Thin Aptian shales with TOCs up to 9% DSDP 693 Aptian organic rich sediments 68m thick TOCs up to 4% 14
An East African Deepwater Cretaceous Source Rock? Winganyongo & Ruaruke Lower Cretaceous Samples measured TOCs of 18% TANZANIA Mocimboa-1 Apt-Alb Slope fan deposition increasing TOC (>1%) with depth, with organic (type III) properties in Albian shales at the base of the well Songo Songo Lower Cretaceous (contamination?) SS 5 TOCs up to 11% SS7 TOC up to 5% SS8 TOC up to 1.57% Semi-restricted circulation? RTI Mid-Ocean Ridge Open Circulation Lower Cretaceous is considered to have gas-prone potential near-shore, but could the deepwater be oil-prone? Marginal ridges along the continental side of the (shear) margin perhaps provides local restricted circulation & anoxic conditions 15
Summary Recent discoveries to the west of the DFZ herald the start of an exciting period of hydrocarbon exploration offshore East Africa. Tanzanian acreage appears have been significantly influenced by strike slip tectonics associated with the DFZ and Tertiary reactivation. Deepwater Cretaceous source rock in East Africa? 2 nd phase of 3D seismic acquired offshore Tanzania (Blocks 1, 3 and 4) in Q1 2011, with a further 3D survey planned for East Pande in Q4 2011. Drilling planned to recommence offshore Tanzania during late 2011 / early 2012.