Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

By Michael E. Brownfield

M ED ATLANTIC ITE RRAN OCEAN EAN SEA

INDIAN OCEAN

Mozambique Coastal SOUTH ATLANTIC OCEAN

INDIAN OCEAN

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Chapter 10 of Geologic Assessment of Undiscovered Hydrocarbon Resources of Sub-Saharan Africa Compiled by Michael E. Brownfield

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_cover.ai Digital Data Series 69–GG

U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Director

U.S. Geological Survey, Reston, Virginia: 2016

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Suggested citation: Brownfield, M.E., 2016, Assessment of undiscovered oil and gas resources of the Mozambique Coastal Province, East Africa, in Brownfield, M.E., compiler, Geologic assessment of undiscovered hydrocarbon resources of Sub-Saharan Africa: U.S. Geological Survey Digital Data Series 69–GG, chap.10, 13 p., http://dx.doi.org/10.3133/ds69GG.

ISSN 2327-638X (online) iii

Contents

Abstract...... 1 Introduction...... 1 Tectonic History and Geology of Mozambique Coastal Province, East Africa...... 4 Petroleum Occurrence in Mozambique Coastal Province, East Africa...... 4 Source Rocks...... 4 Reservoirs, Traps, and Seals...... 7 Exploration...... 9 Geologic Model...... 11 Resource Summary...... 11 For Additional Information...... 12 Acknowledgments...... 12 References...... 12

Figures

1. Map showing Mozambique Coastal Province, Mesozoic-Cenozoic Reservoirs Assessment Unit, Mozambique Channel area, and the Ruvuma Delta along the central coast of East Africa...... 2 2. Map showing generalized geology of East Africa...... 3 3. Map showing reconstruction of the early breakup of Gondwana during the Early Jurassic...... 5 4. Generalized stratigraphic columns of Coastal Mozambique, Mozambique Channel, and Coastal Tanzania, Coastal Morondava Basin, and the Seychelles...... 6 5. Schematic cross section of the Rovuma River delta, northern Mozambique...... 7 6. Stratigraphic column for the onshore and projected offshore parts of the Rovuma Basin, northern Mozambique...... 8 7. Cross section across the Mozambique Channel and the Morondava Basin showing the top of the oil and gas windows...... 9 8. Schematic cross section of the Zambezi Delta, Mozambique...... 10 9. Events chart for the Mesozoic-Cenozoic Petroleum System (734301) and the Mesozoic-Cenozoic Reservoirs Assessment Unit (73430101)...... 11

Table

1. Mozambique Coastal Province assessment results for undiscovered, technically recoverable oil, gas, and natural gas liquids...... 12 iv

Abbreviations Used in This Report

km2 square kilometer AU assessment unit TOC total organic carbon TPS total petroleum system USGS U.S. Geological Survey Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

By Michael E. Brownfield

Abstract Generation of hydrocarbons from drift and post-rift sources began in the Late Cretaceous and, in parts of the offshore, The main objective of the U.S. Geological Survey’s continues today. Hydrocarbons migrated into Cretaceous and National and Global Petroleum Assessment Project is to assess Paleogene reservoirs and traps. Traps are mostly structural the potential for undiscovered, technically recoverable oil and within the syn-rift section and are both structural and natural gas resources of the United States and the world. As stratigraphic in the post-rift rock units. The primary seals are part of this project, the U.S. Geological Survey completed an Mesozoic and Cenozoic mudstone and shale. Rifted passive assessment of the Mozambique Province in 2011, an area of margin analog was used for assessment sizes and numbers approximately 648,650 square kilometers. The Mozambique because of similar source, reservoirs, and traps. Province contains rift, rift-sag, passive-margin, and drift rocks The U.S. Geological Survey estimated mean volumes of Paleozoic to Holocene age. This assessment was based of undiscovered, technically recoverable conventional oil on data from oil and gas exploration wells and published and gas resources for the Mesozoic-Cenozoic Reservoirs geologic reports. Assessment Unit in the Mozambique Coastal Province. The The Mozambique Province is a priority province for mean volumes are estimated at 11,682 million barrels of oil, the World Petroleum Assessment and was assessed in 2011 182,349 billion cubic feet of gas, and 5,645 million barrels of because of increased exploratory activity and increased natural gas liquids. The estimated mean size of the largest oil interest in its future oil and gas resource potential. The field that is expected to be discovered is 1,041 million barrels assessment was geology based and used the total petroleum of oil and the estimated mean size of the expected largest gas system concept. The geologic elements of a total petroleum field is 7,976 billion cubic feet of gas. For this assessment, system consist of hydrocarbon source rocks (source-rock a minimum undiscovered field size of 5 million barrels of maturation and hydrocarbon generation and migration), oil equivalent was used. No attempt was made to estimate reservoir rocks (quality and distribution), and traps for economically recoverable reserves. hydrocarbon accumulation. Using these geologic criteria, the U.S. Geological Survey defined the Mesozoic-Cenozoic Composite Total Petroleum System with one assessment unit, the Mesozoic-Cenozoic Reservoirs Assessment Unit, an area Introduction of approximately 464,420 square kilometers. At the time of the assessment, the Mozambique Coastal Province contained The main objective of the U.S. Geological Survey’s only two gas accumulations exceeding the minimum size of (USGS) National and Global Petroleum Assessment Project is 30 billion cubic feet of gas; the province is considered to be to assess the potential for undiscovered, technically recover- underexplored on the basis of its exploration history. able oil and natural gas resources of the United States and the Oil and gas were generated from Permian to Paleogene world (U.S. Geological Survey World Conventional Resources source rocks. Jurassic Karoo-age lacustrine and continental Assessment Team, 2012). As part of this program, the USGS rocks source rocks average 4.0 to 5.0 weight percent total completed an assessment of the Mozambique Coastal Province organic carbon. Lower to Middle Jurassic restricted marine in 2011 (fig. 1), an area of approximately 648,650 square rocks contain as much as 9 weight percent organic carbon, and kilometers (km2). The Mozambique Province contains rift, Cretaceous Type II source rocks contain as much as 12 weight rift-sag, passive-margin, and drift rocks of Paleozoic to percent organic carbon. Hydrocarbon generation of syn-rift Holocene age. This assessment was based on data from oil and Karoo-age sources began in the Middle Jurassic, whereas the gas exploration wells, discovered and producing fields (IHS generation from Middle Jurassic to Early Cretaceous syn-rift Energy, 2009), and published geologic reports. Generalized sources began in the Late Jurassic to Early Cretaceous. geology of east Africa is shown in figure 2. 2 Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

30°E 34°E 38°E 42°E 46°E 50°E 54°E 58°E 62°E 66°E 70°E

KENYA 2°S RWANDA

BURUNDI SEYCHELLES

6°S TANZANIA

Rovuma Delta 10°S ZAMBIA COMOROS MOZAMBIQUE Mayotte 14°S MALAWI INDIAN OCEAN

18°S MADAGASCAR ZIMBABWE MAURITIUS

Réunion 22°S

SWAZILAND 26°S SOUTH AFRICA Mozambique Coastal 30°S 7343 LESOTHO

34°S

Base from U.S. Geological Survey digital data, 2002 0 150 300 KILOMETERS World Geodetic System 1984 (WGS 84) Prime Meridian, Greenwich, 0° 0 150 300 MILES EXPLANATION AFRICA Mozambique Coastal Province boundary Mesozoic-Cenozoic Reservoirs Assessment Unit boundary Gas field

Mozambique INDEX MAP Coastal 7343 Figure 1. Locations of the Mozambique Coastal Province, Mesozoic-Cenozoic Reservoirs Assessment Unit, Mozambique Channel area, and the Ruvuma Delta along the central coast of East Africa. (Stratigraphic columns for the Mozambique Channel and Rovuma Delta are shown in figures 4 and 6.)

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_figure01.ai Introduction 3

Ogaden Aswa Shear Zone Basin MOGADISHU

Continent-oceanic boundary (COB) Congo Basin

Cupa Fault Zone Mombasa Somali Oceanic Basin TANZANIA

Dar es Salaam Mandawa Basin Rovuma Delta

Majunga INDIAN OCEAN Basin

MOZAMBIQUE

Tsimiroro Field Davie Fracture Zone Beira

1,000

Mozambique Channel Mozambique MADAGASCAR Basin

Kalahari Basin MAPUTO Continent-oceanic boundary Morondava (COB) Basin Karroo Basin 0 200 400 600 KILOMETERS

0 200 400 600 MILES EXPLANATION

Tertiary—Volcanic province Continental crust—Palo fill Post Early Jurassic—Passive Contact margin basin Fault or fault zone—Dashed where approximate. Arrows show relative Permian-Triassic–Early motion Jurassic—Karoo-age rock Graben—Teeth on downthrown side Phanerozoic—Intracratonic Bathymetric contour, 1,000 meter basin line—Location approximate Undifferentiated—Precambrian basement Figure 2. Generalized geology of East Africa. Modified from Ophir Energy Company (2011). 4 Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

The Mozambique Province, which was a priority carbonate platform that was later covered by Upper Jurassic province for the World Petroleum Assessment, was assessed to Cretaceous marine deposits (figs. 4, 5). During the in 2011 because of increased energy exploration activity mid-Cretaceous the passive margin basin again became the and increased interest in its future oil and gas resource site for deposition of open-marine sediments. potential. The assessment was geology based and used the A stratigraphic column for the offshore and onshore total petroleum system concept. The geologic elements of parts of the Rovuma Basin and Delta along the northern a total petroleum system include hydrocarbon source rocks part of Mozambique is shown in figure 6. Since 2006 and (source-rock maturation and hydrocarbon generation and the 2011 assessment, several new hydrocarbon discoveries migration), reservoir rocks (quality and distribution), and have been found in the offshore part of the delta (Law, 2001; traps for hydrocarbon accumulation. Using these geologic IHS Energy, 2009; IHS Energy, 2012). Three generalized criteria, the USGS defined the Mesozoic-Cenozoic Composite seismic cross sections drawn from onshore to offshore are Total Petroleum System (TPS) with one assessment unit, shown in figures 5, 7, 8. These seismic profiles have imaged the Mesozoic-Cenozoic Reservoirs Assessment Unit potential source rock units and prospects in the offshore (AU) (fig. 1), an area of approximately 464,420 km2. The parts of northern Mozambique (Law, 2001; Ophir Energy total petroleum system was defined to include Mesozoic Company, 2011). to Paleogene lacustrine and marine source rocks and conventional reservoirs. Petroleum Occurrence in Mozambique Tectonic History and Geology Coastal Province, East Africa of Mozambique Coastal Province, Source Rocks East Africa The Mesozoic-Cenozoic Composite Total Petroleum The Mozambique Coastal Province is directly related to System was defined to include Mesozoic to Paleocene the breakup of Gondwana (fig. 3) in the late Paleozoic and source rocks and conventional reservoirs (fig. 4). The Mesozoic (Coster and others, 1989; Reeves and others, 2002; Permian to Triassic section contains fluvial and lacustrine Rusk, Bertagne & Associates, 2003). The province developed source rocks averaging 5 to 6 weight percent total organic in four phases: (1) a pre-rift stage that started during the carbon (TOC); some samples have as much as 17.4 weight Carboniferous during which a mantle plume caused uplift, percent TOC (Envoi—Energy Venture Opportunities extension, microplate formation, rifting, and volcanism; International, 2011). The Lower to Middle Jurassic contains (2) a syn-rift phase that started during the Permo-Triassic restricted marine Type II kerogen source rocks, marginal and continued into the Jurassic, which formed grabens and marine and deltaic Types II and III kerogen source rocks, half-grabens and the deposition of possible lacustrine and and Type I lacustrine source rock (Cope, 2000; Rusk, continental source rocks; (3) a syn-rift–drift phase that began Bertagne & Associates, 2003). The offshore part of Ruvuma in the Middle Jurassic and continued into the Paleogene, Delta contains Early to Middle Jurassic restricted marine depositing sediments of marine clastic rocks and carbonate Type II source rocks with TOC contents as much as 12 weight and, during periods of restricted-marine conditions, depositing sediments of marine source rocks; and (4) a passive-margin percent (Cope, 2000). Late Jurassic to Early Cretaceous phase that began in the late Paleogene and continues to the marlstone contains Type II and Type III kerogen with as present (Envoi—Energy Venture Opportunities International, much as 5 weight percent TOC (Envoi—Energy Venture 2011). The stratigraphic section present in Mozambique Opportunities International, 2011). Ophir Energy Company Coastal Province is generally the same as the section present (2007) reports that Aptian shale with TOC contents as much in the coastal Morandava Basin, coastal Tanzania, and the as 9 weight percent. Upper Cretaceous marine sources Seychelles (figs. 2, 4) (Rusk, Bertagne & Associates, 2003). contain Type II and Type III kerogen with TOC contents The opening of the Indian Ocean began in the as much as 7.4 weight percent and Eocene sources contain Permian and continued into the Jurassic during the syn-rift Type II and Type III kerogen with TOC contents as much as stage (Reeves and others, 2002). In the Middle Jurassic, 12.1 weight percent (Cope, 2000). These source rocks have Madagascar, India, and north Mozambique separated been found in the Ruvuma Delta in northern Mozambique and from Africa (fig. 3) and formed a passive margin and a southern Tanzania. Petroleum Occurrence in Mozambique Coastal Province, East Africa 5

HORN OF AFRICA

Anza Rift KENYA

Saurastra Cambay Rift

INDIA

TANZANIA SEYCHELLES Narmada-Son MADAGASCAR

INDIA Mikume Rift

Selous Basin

SRI LANKA NORTH

MOZAMBIQUE

EAST ANTARCTICA

0 100 200 KILOMETERS

0 100 200 MILES

EXPLANATION

Precambrian crustal fragment

Rift-related rock Line of latitude or longitude— Oriented as on modern map Figure 3. Reconstruction of the early breakup of Gondwana during the Early Jurassic (200 Ma). Modified from Reeves and others (2002). 6 Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

Age Coastal Mozambique Channel Coastal Tectonic Tectonic Mozambique and Coastal Tanzania Morandava Basin events Seychelles events W Lithology E Envir. Lithology W Lithology E Envir. East Africa W Lithology E Envir. Seychelles Fluvial Deltaic to Deltaic cont.

Neogene Deltaic Shallow Marine marine R Drift TERTIARY R Paleogene breakup Rift Seychelles-India Marine

R Upper Marginal sag and passive margin Shallow marine and open

and marginal marine R Marginal sag and drift CRETACEOUS Restricted marine, open to continental Lower Shallow marine Marine Upper and drift Madagascar- Madagascar-

R Seychelles-India ? Seychelles-India Rift, marginal sag breakup from Africa breakup from Africa M Rift and marginal sag marine, and open marine Restricted marine, shallow JURASSIC Zones of reservoir potential ? R Lower lagoonal to continental Rifting and marginal sag Shallow marine Upper TRIASSIC M ? R

L ? ? and uplift

U ? Continental with minor marginal marine Recurrent rifting and uplift

? ? Recurrent rifting L

PERMIAN R marginal marine Continental with minor marginal marine Continental with minor Upper

Middle- ? IFEROUS CARBON-

BRIAN Basement PRECAM-

EXPLANATION

Sandstone Limestone Reservoir rock, East Africa R Potential reservoir Oil field Sandstone and conglomerate Salt Contact—Dashed where location approximate Gas field Shale Igneous rock—Extrusive Unconformity Sandy shale Igneous rock—Oceanic crust Extent uncertain Source rock Calcareous shaley marlstone Basement

Figure 4. Generalized stratigraphic columns of Coastal Mozambique, Mozambique Channel and Coastal Tanzania, Coastal Morondava Basin, and the Seychelles along the east coast of Africa (fig. 1). W, west; E, east; Envir., environment; cont., continental; L, Lower; M, Middle; U, Upper. Modified from Rusk, Bertagne & Associates (2003) and PetroSeychelles (2013).

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_figure04.ai Petroleum Occurrence in Mozambique Coastal Province, East Africa 7

Rovuma onshore Rovuma offshore

WEST EAST

Mecupa Caravel Ironclad Windjammer

Tertiary

INDIAN OCEAN

Cretaceous

Jurassic

NOT TO SCALE EXPLANATION

Sandstone reservoir rock—Turbidite sandstone unit, deep water fan, and growth-fault-related sand Carbonate

Basement Contact Fault—Growth fault, normal fault, and thrust fault Fault Caravel Drill hole and identifier—Approximate depth to target depth Figure 5. Schematic cross section of the Rovuma River delta, northern Mozambique. Modified from Law (2011). Not to scale.

Oil and gas generation most likely began in the Early & Associates, 2003; Law, 2011). Triassic to Middle Jurassic Cretaceous for the Upper Jurassic syn-rift sources in the syn-rift rocks contain possible alluvial fans, fan deltas, fluvial province (Coster and others, 1989). Oil and gas generation deltas, and lacustrine sandstones reservoirs. The Late Jurassic began in the Late Cretaceous for the Barremian to Aptian post-rift rocks contain reef and platform carbonate rocks that post-rift sources and in the offshore parts of the province the are potential reservoirs. The post-rift Cretaceous rocks contain Late Cretaceous post-rift sources began oil and gas generation regressive and transgressive marine sandstone, slope-turbidite began in the early Paleogene and is most likely continu- sandstone and basin-floor fan sandstone reservoirs (Coster and ing today (Coster and others, 1989; Envoi—Energy Venture others, 1989). Upper Cretaceous and Cenozoic passive-margin Opportunities International, 2011). Oil- and gas-generation rocks contain possible carbonate reservoirs and Maastrichtian windows are shown in figure 7 for the Mozambique and Paleocene turbidite and basin-floor fan reservoirs (Cope, Channel and the Morondava Basin (Envoi—Energy Venture 2000). Volcanic rocks found within the Karoo age rocks and Opportunities International, 2011). Cretaceous section may have degraded some of the reservoirs. The Mesozoic-Cenozoic Reservoirs Assessment Unit (fig. 1) contains sandstone reservoirs that mostly are Reservoirs, Traps, and Seals associated with growth-fault-related structures such as rotated fault blocks within the continental shelf, deep water fans, \\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_figure05.aiThe Mozambique Coastal Province and the Mesozoic- turbidite sandstone units, and slope truncations along the Cenozoic Reservoirs Assessment Unit (fig. 1) contain present-day shelf and paleoshelf edge (Cope, 2000; Rusk, Mesozoic and Cenozoic clastic reservoirs (Coster and others, Bertagne & Associates, 2003; Law, 2011). For example, the 1989; Nairn and others, 1991; Cope, 2000; Rusk, Bertagne Rovuma River delta (fig. 5) contains turbidite sandstone units, 8 Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

Period Epoch Stage West Onshore Offshore East Quaternary Pleistocene Calabrian Piacenzian Pliocene Zanclian ? Messinian Chinda Tortonian Formation Mikindani Formation Rovuma Delta Complex Miocene Serravallian Langhian Neogene Burdigalian Aquitanian Chattian Oligocene Rupelian

Cenozoic Priabonian Bartonian Quissanga Formation Eocene Lutetian

Paleogene Ypresian Thanetian Paleocene Selandian Alto Jingone Formation Danian Maastrichtian

Campanian Late Mifume Formation Santonian Coniacian Turonian Cenomanian

Albian Macomia Formation Cretaceous Aptian

Early Barremian

Mesozoic Hauterivian Pemba Formation Valanginian Berriasian Tithonian Late Kimmeridgian Oxfordian Callovian Bathonian

Jurassic Middle Bajocian Aalenian

EXPLANATION

Sandstone Continental Marine shale, siltstone, Contact and sandstone clastic rock Unconformity Conglomerate Marl Present coastline Paralic clastic rock Calcareous sandstone

Marine sandstone Shelf carbonate

Figure 6. Stratigraphic column for the onshore and projected offshore parts of the Rovuma Basin, northern Mozambique. Middle and Lower Jurassic units shown in figure 4, such as the Lower Jurassic salt, are not shown. Modified from Key and others (2008).

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_figure06.ai Exploration 9

Île Juan de Nova Exclusive Economic Zone FRENCH SOUTHERN AND MOZAMBIQUE ANTARCTIC LANDS MADAGASCAR Ironclad Mnazi Discovery Bay Field (Offset to (Offset to North) Windjammer Tsimiroro WEST-NORTHWEST South) Discovery Heavy Oil EAST-SOUTHEAST (Offset to Manambolo Field Bemolanga X North) Juan de Gas Field Tar Sands X' KILOMETERS Nova Island SEA LEVEL Mozambique Channel 2 Top of Oil Window 4 Top of Gas Window 6

8 Davie Fracture Zone Morondava Basin 10

EXPLANATION Rovuma Delta Tertiary Contact MALAWI Fault Cenozoic Ironclad X Discovery Oil field and Majunga Basin Upper Cretaceous identifier X'

Lower Cretaceous MOZAMBIQUE Mnazi Bay Field Gas field and Mozambique Channel Jurassic MADAGASCAR identifier INDIAN Morondava Basin OCEAN Triassic to Permian Line of section Shallow and Basement rock deepwater prospect Volcanic INDEX MAP

Figure 7. Cross section across the Mozambique Channel and the Morondava Basin (line of section on index map) showing the top of the oil- and gas-generation windows. Cross section is approximately 420 kilometers long, not to scale. Modified after Envoi—Energy Venture Opportunities International (2011).

deep-water fan, and growth-fault-related sandstone reservoirs found in Karoo-age grabens and Mesozoic half-grabens, (Law, 2011). A seismic profile reported by Walford and others faulted drape anticlines, and inversion-related anticlines (2005) interpreted the Late Cretaceous and Cenozoic section (Cope, 2000; Rusk, Bertagne & Associates, 2003). showing the Domo Sandstone, a potential reservoir and clinoform packages, channeling, slumping, and growth faults in the offshore part of the Zambezi Delta (fig. 8). Triassic to Jurassic syn-rift rocks contains structural traps Exploration related to graben and half grabens. Lower Cretaceous post-rift rocks (drift and passive-margin) contain stratigraphic traps At the time of the 2011 assessment, the Mozambique Province contained five gas fields and no oil fields \\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_figure07.aisuch as transgressive and regressive sandstones and structural traps including salt structures, drape anticlines, and flower (IHS Energy, 2009) and is considered to be underexplored structures (Rusk, Bertagne & Associates, 2003; Law, 2011). on the basis of its limited exploration activity. Recent Upper Cretaceous and Paleogene post-rift rocks (drift and hydrocarbon shows are limited to the Cretaceous-Tertiary passive-margin) contain both structural and stratigraphic traps offshore drift and passive-margin section (Law, 2011). in growth-fault-related structures, rotated fault blocks within Hydrocarbon shows in exploration wells on the the continental shelf, deep-water fans, turbidite units, and slope continental shelf and upper slope provide evidence for the truncations along the present day shelf and paleoshelf edge. existence of an active petroleum system containing Mesozoic The primary reservoir seals are Mesozoic and Cenozoic source rocks and for the migration of the hydrocarbons into drift and marginal-marine mudstone and shale (Nairn and Cretaceous and Cenozoic reservoirs, most likely since the others, 1991; Cope, 2000). Secondary fault-related seals are Late Cretaceous. 10 Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

TWO WAY A A' TIME IN INDIAN SECONDS Well A Well B OCEAN 0 Seafloor To p To Pli 1 M p M oce id ioc ne dle M ene T ioce op Ol ne Top Eocene igocene 2 Top C Domo Sandstone retac slumping eous 3 channeling

4

5

0 5 10 KILOMETERS Zambezi River 0 5 10 MILES

EXPLANATION MOZAMBIQUE

Tertiary A INDIAN OCEAN Cretaceous Beira A' Jurassic Line of section Seismic reflector Contact Fault INDEX MAP

Well A Well and identifier

Figure 8. Schematic cross section of the Zambezi Delta, Mozambique. Modified from Walford and others (2005).

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Geologic Model PETROLEUM SYSTEM EVENTS The geologic model developed for the assessment of conventional oil and gas in the Mozambique Coastal Province and the Coastal Plain and Offshore Assessment Unit is as follows: ACCUMULATION 1. Oil and gas was generated from Permian to Jurassic

Karoo-age lacustrine and continental rocks (rift stage). MIGRATION- The lacustrine rocks contain TOC values averaging 4.0 to 5.0 weight percent. Early to Middle and Jurassic restricted ROCK UNITS RESERVOIR ROCKS

OVERBURDEN ROCKS PRESERVATION Age in million years (Ma) SOURCE ROCKS SEAL ROCKS TRAP FORMATION marine rocks contain as much as 9 weight percent TOC, GENERATION- 0 and Cretaceous marine rocks contain Type II kerogen Plio with as much as 12 weight percent TOC. Generation of Neogene Deltaic Mio hydrocarbons in syn-rift Karoo-age source rocks most 23 likely began in the Middle Jurassic, whereas generation Olig Deltaic of hydrocarbons in Middle Jurassic to Early Cretaceous syn-rift source rocks began in the Late Jurassic to Early Paleogene Eoc Cretaceous. Generation of early post-rift sources most 50 likely began in the Late Cretaceous. The drift and post-rift Pal 65 source rocks most likely began generating hydrocarbons in the Late Cretaceous. Hydrocarbon generation most L likely continues today in the offshore parts of the

assessment unit. Cretaceous Open and marginal marine 100 2. Generated hydrocarbons migrated into mostly Cretaceous and Paleogene sandstone reservoirs. E 3. Hydrocarbon traps are structural within the syn-rift rock units and are both structural and stratigraphic in the post- rift rock units. 146 Marine 4. The primary reservoir seals are Mesozoic and Cenozoic 150 L mudstone and shale. 5. The rifted passive margin analog (Charpentier and M open marine

Jurassic Restricted and others, 2007) was used for assessment sizes and numbers because of similar source, reservoirs, and traps. E

An events chart (fig. 9) for the Mesozoic-Cenozoic 200 200 Continental Composite TPS and the Mesozoic-Cenozoic Reservoirs AU summarizes the age of the source, seal, and reservoir rocks L and the timing of trap development, generation, and migration. Triassic

M Rift Resource Summary E 250 251 L Permian At the time of this 2011 assessment, the Mozambique E Coastal Province contained only five gas accumulations exceeding the minimum size of 30 billion cubic feet of gas; Figure 9. Events chart for the Mesozoic-Cenozoic Total Petroleum this province is considered to be underexplored on the basis System (734301) and the Mesozoic-Cenozoic Reservoirs Assessment of its level of exploration activity. Using a geology-based Unit (73430101) in the Mozambique Coastal Province, South Africa. assessment, the USGS estimated mean volumes of undiscov- Gray, rock units present; yellow, age range of reservoir rocks; green, ered, technically recoverable conventional oil and gas age ranges of source and overburden rocks, timing of trap formation, resources for the Mesozoic-Cenozoic Reservoirs Assessment and generation, migration, and preservation of hydrocarbons; wavy Unit in the Mozambique Coastal Province (table 1). The line, unconformity. Divisions of geologic time conform to dates in mean volumes are estimated at 11,682 million barrels of oil, U.S. Geological Survey Geologic Names Committee (2010). Ma, 182,349 billion cubic feet of gas, and 5,645 million barrels of thousands of years ago; Plio, Pliocene; Mio, Miocene; Olig, Oligocene; natural gas liquids. The estimated mean size of the largest oil Eoc, Eocene; Pal, Paleocene; L, Late; E, Early; M, Middle; ?, uncertain.

\\IGSKAHCMVSFS002\Pubs_Common\Jeff\den13_cmrm00_0129_ds_brownfield\dds_69_gg_ch10_figures\ch10_figures\ch10_figure09.ai 12 Assessment of Undiscovered Oil and Gas Resources of the Mozambique Coastal Province, East Africa

Table 1. Mozambique Coastal Province assessment results for undiscovered, technically recoverable oil, gas, and natural gas liquids.

[Largest expected mean field size, in million barrels of oil and billion cubic feet of gas; MMBO, million barrels of oil; BCFG, billion cubic feet of gas; MMBNGL, million barrels of natural gas liquids. Results shown are fully risked estimates. For gas accumulations, all liquids are included as natural gas liquids (NGL). Undiscovered gas resources are the sum of nonassociated and associated gas. F95 represents a 95-percent chance of at least the amount tabulated; other fractiles are defined similarly. Fractiles are additive under assumption of perfect positive correlation. AU, assessment unit; AU probability is the chance of at least one accumulation of minimum size within the AU. TPS, total petroleum system. Gray shading indicates not applicable] Largest Total undiscovered resources Total Petroleum Systems (TPS) Field expected Oil (MMBO) Gas (BCFG) NGL (MMBNGL) and Assessment Units (AU) type mean F95 F50 F5 Mean F95 F50 F5 Mean F95 F50 F5 Mean field size Mozambique Coastal-Mesozoic-Cenozoic Composite TPS Oil 1,041 6,268 11,174 18,857 11,682 8,423 15,615 27,238 16,425 225 421 744 444 Mesozoic-Cenozoic Reservoirs AU Gas 7,976 93,486 158,654 263,301 165,924 2,915 4,978 8,270 5,201 Total Conventional Resources 6,268 11,174 18,857 11,682 101,909 174,269 290,539 182,349 3,140 5,399 9,014 5,645 field that is expected to be discovered is 1,041 million barrels Coster, P.W., Lawrence, S.R., and Fortes, G., 1989, of oil and the estimated mean size of the expected largest gas Mozambique—A new geological framework for hydro- field is 7,976 billion cubic feet of gas. For this assessment, carbons exploration: Journal of Petroleum Geology v. 12, a minimum undiscovered field size of 5 million barrels of no. 2, p. 205–230. oil equivalent was used. No attempt was made to estimate Envoi—Energy Venture Opportunities International, 2011, economically recoverable reserves. Mozambique Channel (offshore S.E. Africa), Juan de Nova Est Permit, Morondava Basin: Envoi Limited, London, http://envoi.co.uk/wp-content/uploads/2012/11/P191 For Additional Information WessexSEAfricaJuanDeNovaSynopsis.pdf. Accessed March 20, 2013. Assessment results are available at the USGS IHS Energy, 2009, International petroleum exploration and Central Energy Resources Science Center website: production database [current through December 2009]: http://energy.cr.usgs.gov/oilgas/noga/ or contact Michael E. Available from IHS Energy, 15 Inverness Way East, Brownfield, the assessing geologist [email protected]( ). Englewood, Colo. 80112 USA. IHS Energy, 2012, International petroleum exploration and production database [current through December 2009]: Acknowledgments Available from IHS Energy, 15 Inverness Way East, Englewood, Colo. The author wishes to thank Mary-Margaret Coates, Key, R.M., Smith, R.A., Smelror, M., Saether, O.M., Jennifer Eoff, Christopher Schenk, and David Scott for their Thorsnes, T., Powell, J.H., Njange, F., and Andamela, E.B., suggestions, comments, and editorial reviews, which greatly 2008, Revised lithostratigraphy of the Mesozoic-Cenozoic improved the manuscript. The author thanks Wayne Husband succession of the onshore Rovuma Basin, northern coastal for his numerous hours drafting many of the figures used Mozambique: South African Journal of Geology, v. 111, in this manuscript, and Chris Anderson, who supplied the no. 1, p. 89–108. Geographic Information System files for this assessment. Law, Carol, 2011, Northern Mozambique—True “wild- cat” exploration in east Africa: American Association of Petroleum Geologists Search and Discovery article References 110157(2011), 39 p. Nairn, A.E.M., Lerche, I., and Iliffe, J., 1991, Geology, basin Charpentier, R.R., Klett, T.R., and Attanasi, E.D., 2007, analysis, and hydrocarbon potential of Mozambique and Database for assessment unit-scale analogs (exclusive of the the Mozambique Channel: Earth-Science Reviews, v. 30, United States) Version 1.0: U.S. Geological Survey Open- no. 1–2, p. 81–124. File Report 2007–1404, 36 p., CD–ROM. PetroSeychelles, 2013, The Seychelles licensing initia- Cope, M., 2000, Tanzania’s Mafia deepwater basin indicates tives: NAPE, February 5–8, Houston, Texas, 46 p., potential on new seismic data: Oil and Gas Journal, v. 98, http://www.internationalpavilion.com/NAPE%202013%20 issue 33, 6 p., http://www.ogj.com/articles/print/volume-98/ Presentations/Seychelles.pdf. issue-33/exploration-development/tanzanias-mafia- Ophir Energy Company, 2007, Hydrocarbon Prospectively deepwater-basin-indicates-potential-on-new-seismic- of Deepwater Southern Tanzania—East African Petroleum data.html. Last accessed February 28, 2013. Conference: Arusha, Tanzania, March 7–9, 2007, 26 p. References 13

Ophir Energy Company, 2011, Exploration in Tanzania and U.S. Geological Survey Geologic Names Committee, 2010, Madagascar—Evolution Securities East Africa Conference: Divisions of geologic time: U.S. Geological Survey Fact London, January 13, 2011, 27 p. Sheet 2010−3059, 2 p. Reeves, C.V., Sahu, B.K., and de Wit, M., 2002, A re-examina- U.S. Geological Survey World Conventional Resources tion of the paleo-position of Africa’s eastern neighbours in Assessment Team, 2012, An estimate of undiscovered Gondwana: Journal of African Earth Sciences, v. 34, no. 1, conventional oil and gas resources of the world, 2012: p. 101–108. U.S. Geological Survey Fact Sheet 2012–3042, 6 p. Available at http://pubs.usgs.gov/fs/2012/3042/ Rusk, Bertagne & Associates, 2003, Petroleum geology and geophysics of the Mozambique Channel, executive sum- Walford, H.L., White, N.J., and Sydow, J.C., 2005, Solid sedi- mary: 20 p., http://www.petrocommunicators.com/moz/ ment load history of the Zambezi Delta: Earth and Planetary index.htm. Last accessed March 6, 2012. Science Letters, v. 238, no. 1–2, p. 49–63.

M ED ATLANTIC ITE RRAN OCEAN EAN SEA

INDIAN OCEAN

Mozambique Coastal SOUTH ATLANTIC OCEAN

INDIAN OCEAN

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