• Participation in the under-explored pre-salt play within the oil prone margins of the Cretaceous Dentale Palaeo-Trough immediately outboard of the proven Etame Field and Dussafu PSC discoveries

• Large new prospects defined in three pre- and post-salt plays unlocked by latest CCG BroadSeis 3D PSDM seismic

• Combined mean resource potential estimated to be in excess of 1+ billion bbls recoverable

• Globally competitive Licence terms negotiated prior to the introduction of revised fiscal regime in 2014

• Material 40+% interest available for a contribution to planned drilling commitment

Project Synopsis: P234

Offshore Gabon South Gabon Basin

Tchicuate Block (G13)

October 2016

P234 Marathon (Gabon)

Opportunity for early participation in the drilling phase of the unexplored, but highly prospective, Tchicuate (G13) Block situated on the oil prone margin of the Dentale Palaeo-Trough. Large 3D PSDM defined prospects are estimated to contain a combined 1,200 MMboe mean recoverable resource within the three plays now mapped immediately outboard of the proven shelf fairway.

Marathon Oil Corporation

Introduction: Envoi has been commissioned by Marathon Oil Corporation (‘Marathon’) to assist in its search for a partner to join in the drilling phase of its 1,120 km2, 100% owned and operated Tchicuate Licence in the South Gabon Basin, offshore Gabon. The Block is prospectively located for the best development of the pre-salt reservoir potential on the more oil prone flanks of the Dentale Palaeo-trough, immediately outboard of the Dussafu oil discoveries and producing Etame Field fairway. The Tchicuate Licence also benefits from favourable contract terms ensuring that significant returns can be generated from the large potential identified. Marathon wishes to find a partner to join in the preparation and drilling of the exploration well planned for early 2018. The Tchicuate area exhibits stacked pay potential across three different pre-salt and post-salt plays that can be tested with one wellbore. New 3D PSDM data over the licence has unlocked the potential within the pre-salt Gamba and Dentale plays. These plays have already been proven regionally by numerous discoveries made over the last 30 years in the onshore and offshore parts of the Southern Gabon Basin. These include the discoveries immediately inbound of the Tchicuate Licence, where a number of pre-salt fields have been found on the shelf, including the Etame Field complex (which includes Etame itself plus the Tchibala, Ebouri and Avouma fields, which are reported to contain a combined estimated 139 MMboe), the Walt Whitman-1 Gamba discovery (ca

5 MMboe) and the more recent Ruche and Tortue discoveries which will be developed together. Additionally, Marathon has identified potential in the post-salt Madiela play that is analogous to the Sendji and Pinda carbonate raft plays in neighbouring Congo and Angola further to the south. Marathon’s revised potential resource inventory of all three plays is now estimated to have a total combined mean resource potential of 1.2 billion boe and an upside in excess of 2 billion boe. This resource potential significantly exceeds the minimum for commercial standalone development in the moderately deep water depths (800 - 1,500m). Exploration History: Oil and gas has been explored for in Gabon since the 1920s, when oil seeps were first identified. The first exploration well was drilled around 1934, with the first commercial production established onshore in the Ozouri field by Elf in 1956. Gabon has progressively become an established oil producer along with the other West African passive margin producing countries. Gabon now relies upon hydrocarbons for around half of its GDP and up to 80% of its export revenues. Gabon is established as one of West Africa’s proven – producing E&P destinations. It is currently Africa’s 7th largest oil producer with some 240,000 bbls daily oil production from 71 fields and proved oil reserves of

P234 Marathon (Gabon) over 3 billion barrels. In 1997, Gabon’s daily oil production peaked at around 370,000 bbl/d but fell by almost 25% over the next six years as onshore fields depleted and low oil prices stalled new exploration and development. Recently, new discoveries in deeper water have been made as renewed exploration has been successful and is evidence of the large untapped hydrocarbon potential that remains in Gabon. Prior to these recent discoveries, most of the exploration has been onshore or offshore on the shelf in the shallower water less than 200 metres deep. The Tchicuate licence is situated in the South Gabon Basin, one of the series of prolific hydrocarbon basins adjoining the west coast of Africa. The deeper water pre-salt section in southern Gabon remains under- explored but, unlike many other deeper water plays, Gabon’s proven provenance has already been confirmed by the 2 large discoveries made northwest of the Tchicuate Block in the more gas-prone, central part of the Dentale Palaeo-Trough. These comprise the Diaman-1 discovery, in which Marathon is also a partner, and the Leopard-1 discovery in the adjacent acreage. Diaman-1 was Gabon’s first deepwater pre-salt discovery, drilled 2013 by Total in its Diaba Block. This discovery, some 120 km from the coast in 1,754 metres of water, is over 60 km seaward of any previous discovery and encountered over 50 metres of net hydrocarbon pay. As a result it has opened up the whole new unexplored region of the deeper offshore. Marathon, as a partner in the Diaba Block, have applied their resulting knowledge to add to the development of a regional understanding of the play and now recognise that Tchicuate is located in the oil prone part of this highly prospective play trend to the south. Significantly, two other deeper water well tests of the Dentale Trough’s pre-salt play in the region encountered hydrocarbons. These include the Sputnik-1 discovery, drilled by Perenco in 2014, which is reported to have encountered an uncommercial gas accumulation and the N’Komi-1 well, drilled by Shell in 2014, which is thought to have encountered a residual gas column within a breached trap. Significantly, the two discoveries and the two other wells prove that 100% of the deeper water pre-salt closures tested offshore Gabon were at one time charged with hydrocarbons. In the shallower waters to the northeast of Tchicuate, the pre-salt play was first confirmed by drilling in the late 1970s, with additional discoveries in the 80s and 90s including the Etame field. Put on production in 2001, the Etame field complex has cumulatively produced over 90 MMboe from pre-salt Gamba and

Dentale sands. Immediately east of Marathon’s Tchicuate Licence, Harvest added two - albeit minor - oil discoveries within their Dussafu Block to the existing Moubenga Dentale and Walt Whitman Gamba discoveries with their Ruche-1 and Tortue-1 wells between 2011 and 2012. These encountered gross 30+m and 60 m hydrocarbon columns respectively in the combined Gamba and stacked Dentale formations. Although a joint development of the combined resources of these small fields remains a future possibility, these shelf discoveries have proven the Gamba and Dentale sand play potential on the shelf where they were deposited in a lacustrine fluvial environment. They are, however, now known to thicken westwards where they accumulated over the Atlantic hinge and onto the flanks of the Dentale palaeo-trough that developed during the lower Cretaceous (Barremian-Aptian) times and where the Tchicuate Block is located today. The closest well to the Tchicuate block, the Aulica Marine-1 (ALM-1) well drilled by Shell in 1978 targeting the post salt Madiela play, encountered hydrocarbon shows at the top of the Madiela. Significantly, basin modelling has since demonstrated that the oil shows encountered were generated by lower Cretaceous, pre-salt source rocks - a clear indicator that these will be mature for oil in the Tchicuate Block immediately to the west. The post-salt syn-rift Madiela Formation produces in the Tchatamba field in northern Gabon (MRO discovery) and in the Madiela equivalent Senji Formation in Congo where over 1.4 Bboe recoverable have been discovered in Yombo, N’Kossa and many other fields to the south east. Particularly relevant to progressing exploration of South Gabon’s deeper water acreage, including Tchicuate, has been the acquisition by CGG of a new, large, regional multi-client 3D seismic survey offshore which was acquired in 2015. Marathon carved out an area specifically over the Tchicuate block for independent PSDM processing and delivery of the final data was accepted in in May 2016 ahead of the survey’s multi-client general release in late 2016. The data has been fully interpreted with additional analysis underway with a view to selecting the best drilling locations. Licence History: The Tchicuate area was formerly part of the Anton Marin permit between 1997 and 2009. Total drilled the Jeanette (JNT-1) well to the west, outside of the current licence area, targeting a post-salt structure. After relinquishment, the blocks were reorganised and Marathon formally expressed interest in the blocks in 2011. Later, in the 2013 Gabon Licensing Round, Marathon was the successful bidder

P234 Marathon (Gabon) on the block and beat competition from four other bidders. The G13 Block was subsequently awarded to Marathon in August 2014 for a 6 year term divided into 4 year and 2 year exploration phases and renamed Tchicuate. Regional Evolution: The Gabon Basin originated when the early Cretaceous break-up of Gondwana resulted in a series of extensional basins between what is now West Africa and Brazil. The initial freshwater rift floor environment with fluvial and lacustrine deposits evolved into brackish and then restricted marine environments as the rifting progressed. The thick stratigraphy that resulted is preserved in the present day Dentale Palaeo-trough below a regional salt. Open marine transgressions occurred with the early Atlantic opening and resulted in shelf and slope deposition as the continental margin fully developed. The present day passive margin stratigraphy contains the full progression of the early pre-salt rift, syn-rift and post-salt marine carbonate and siliciclastic sections that contain the stacked play potential.

The Gabon Basin is today divided into the North and South sub-basins, separated by the SW-NE trending transverse N’Komi Fault Zone (Ref: Montage). The resulting stratigraphy in the Gabon Basin today can be sub-divided into pre-salt and post-salt

sequences, where Neocomian-Aptian continental rift deposits are separated from an overlying Albian and younger marine drift sequence by a thick succession of Aptian evaporites. The regional salt presence allows a distinction between the large faulted margin structural traps of the pre-salt formations and the shelf and slope reservoirs of the post-salt. Below the salt, stacked syn-rift fluvial / deltaic sands of the Dentale are unconformably overlain by the regional sands of the Gamba, both of which are significant reservoirs within the Gabon Basin.

Above the evaporites the Madiela Formation, consisting of shallow marine/inner platform-to-platform carbonate facies, developed as individual carbonate shoals with basal clastics which, due to extension and halokinesis of the underlying salt, formed individual raft and turtle structures. Periodic windows in the salt or weld allow the migration of pre-salt hydrocarbons into the Madiela rafts. Top seal is provided by the shale-rich Azile and Cap Lopez formations.

Petroleum Geology & Play Potential: Gabon’s petroleum geology and associated plays can be separated into primary pre-salt (pre- and syn-rift) play potential and secondary post-salt (post-rift) play potential. By comparison with the onshore parts of sub-Saharan West Africa, offshore Southern Gabon - and particularly the shelf edge and deeper water - has seen relatively little exploration. Closer to shore, in addition to Vaalco’s Etame cluster of pre-salt fields (Gamba and Dentale reservoirs), oil production occurs from older syn-rift sediments in the Perenco M’Bya / M’Wengui fields and from the post-salt Madiela equivalent Senji Formation in the Yombo fields to the southeast, offshore Congo.

Pre-Salt: Earliest rift sediments include Vandji/basal sandstones (Grès de Base) which have reservoir potential both onshore and offshore that exhibit up to 25% porosity and 100 mD permeability. This play has been successfully explored onshore and shallow water

P234 Marathon (Gabon) in both Gabon and Congo but is generally not a target, due to depth of burial in deeper water Gabon. Organic-rich lacustrine shales of the Neocomian-age Kissenda and younger Barremian age Melania formations overlie the Grès de Base and together are the main source rocks in Gabon. The Melania is considered a world class source rock and the ‘hot shale’ interval is a particularly rich organic source with TOCs up to 10wt%. Marathon’s main play focus in the Tchicuate Block is the rift related pre-salt Dentale Formation. The Barremian-Aptian Dentale Formation overlies the Melania and consists of inter-bedded sandstones and shales within a lacustrine fluvial deltaic setting. As demonstrated by nearby updip discoveries, the Dentale has stacked reservoir potential with up to 28% porosity and 1D permeability. An erosional period followed the deposition of the Dentale Formation and can be identified in wells and seismic by the presence of the AP2 unconformity. The AP2 unconformity separates the Dentale Formation below from the Aptian aged Gamba sandstones above. The Gamba Formation is interpreted to have been deposited initially in a lacustrine fluvial-deltaic environment that later transitioned to a mixed (paralic) environment. The Gamba sandstones are regionally extensive and exhibit relatively high porosities and permeabilities (up to 30% porosity and 5 Darcy permeability). Historically, the Gamba formation has been the primary reservoir target with Gabon. The pre-salt section is completed with the deposition of the Vembo Formation shales blanketing the region. These shales are thought to represent the full marine incursion into area and the transition from a paralic to a marine environment. Salt: As the Aptian progressed, the Vembo and Gamba Formations were overlain by thick Ezanga salt deposits which act as a regional seal across the pre-salt rift reservoirs. These evaporites, up to 500 metres in thickness, were in turn overlain by carbonates and shales of the Albian age Madiela Formation. Syn-sedimentary gravity driven deformation began at the end of the Aptian as the carbonate platform was deposited over the salt. This indicates that differential subsidence had created a dip of the strata below the salt, instigating movement along the salt decollement. The lateral and vertical transition between the salt and the Madiela Formation, with its varying thickness and facies changes, has been a major challenge in seismic imaging in the basin.

Post Salt: The post-rift infill and drift continued as the passive margin developed from the late Cretaceous to the present day. Fields offshore Congo, immediately south east of the Tchicuate Licence, including Masseko (18 MMbor), Loango (209 MMbor) and Yombo (115 MMbor), are understood to consist of shallow marine carbonates and high energy margin carbonate shoals in the base lower Cretaceous Cap Lopez / Upper Madiela formations. Recent regional work suggests that these reservoirs extend north into the offshore part of southern Gabon and remain key secondary shallower play objectives in the Marathon acreage due to the nearby production. Traps may be enhanced by a stratigraphic component to closures as seen in Yombo; however, being shallow, there is a risk that any oil in this play may be biodegraded as evidenced by some of the 18-22º API oils encountered in the Congo fields. Hydrocarbon Potential: The Tchicuate block lies just west of the Atlantic Hinge on the upper flanks of the Dentale Palaeo-Trough. This area is interpreted as more oil prone, based on Marathon’s regional basin structure, source and maturity modelling. This contrasts with the deeper, more gas prone area in the central parts of the Dentale Trough to the northwest. Here, modelling suggests that the pre-salt play sediments matured early when the oil generated is likely to have migrated before adequate traps and seals were in place. By the time the reservoirs were sealed, the source was deeper and mature for gas and condensate as confirmed by the recent Shell

P234 Marathon (Gabon) Leopard-1 and Total Diaman-1 discoveries. Marathon’s work suggests that the Tchicuate block remain mature for oil present day. Seismic: Since acquiring the Licence and commencing operatorship in 2014, Marathon has carried out a comprehensive G&G programme, including the acquisition of CCG’s new regional 25,000 km2 broadband 3D multi-client survey, over the Tchicuate Block. This survey was specifically designed to penetrate and image the complex carbonate and salt structures and was acquired with 10km minimum offsets and frequencies as low as 2.5 Hz. Historically, the presence of salt and the lateral transition to carbonates have caused problems in depth conversion. These issues have also been largely solved by modern acquisition and PSDM processing techniques. This has significantly improved imaging of both the pre- and post-salt sections and enabled a greater geological understanding of the pre-salt structure, significantly reducing prospect risk. Harvest Natural Resources is understood to have utilised these modern techniques in their Dussafu block, immediately east of Tchicuate, which enabled more accurate sub-salt mapping of the Gamba and Dentale objectives and was instrumental defining closures, subsequently confirmed by the successful discoveries made in 2011 in the Ruche-1 (DRM-1) well and the Tortue-1 (DTM-1) well in 2013.

Prospectivity: The results from Marathon’s new 3D PSDM seismic interpretation over their Tchicuate Block has much more accurately confirmed the presence of several large prospects originally defined as leads on old 2D seismic data. The new prospects mapped are mostly 3-way dip closed structures with stacked pre-salt Gamba and Dentale play potential. Intra-formational shales are expected likely to independently seal the reservoir targets in the Dentale, although the pre-salt is mostly sealed regionally by the Ezanga salt formation. Secondary prospectivity is also being mapped in the Albian post salt Madiela play in the Tchicuate Block.

A new stratigraphic Gamba pinch out play concept has also been defined by the new 3D data. While the Gamba Formation has generally been present in pre-salt wells across Gabon, the seismic shows a clear pinchout of the interval below the base of the Ezanga Formation indicating the potential for a stratigraphic trapping of the Gamba. Estimated combined Pmean resource potential for the pre-salt Dentale interval prospects in the newly defined NW, NE and Central areas alone is some 600+ MMboe recoverable with an estimated resource upside in excess of 1.4 Billion boe recoverable.

Discovery of hydrocarbons in the new Gamba pinchout play could add an estimated 200+ MMboe Pmean and upside in excess of 490+ MMboe recoverable to the primary pre-salt play potential, as could the secondary post salt Madiela play prospectivity in the Tchicuate Block which is estimated capable of an additional Pmean 390+ MMboe recoverable.

P234 Marathon (Gabon)

Disclaimer: The information in this memorandum is for guidance only. Neither Envoi Limited (Envoi), or its client(s) (Client) nor any director, officer or employee of Envoi or its Client(s) accepts responsibility for, or makes any representation or warranty, express or implied, with respect to the accuracy or completeness of the information, estimates and opinions contained in this document. This document does not constitute an offer, and neither this document nor the information, estimates and opinions contained in it shall form the basis of any contract. Companies wishing to acquire an interest in the project will be expected to make their own review of all documents and form their own judgments entirely.

© Envoi Limited 2016

Data availability: Marathon now possesses considerable data over its Tchicuate Licence including regional gravity, well data, legacy 2D seismic data sets and the most recent CGG multi-client 3D broadband survey data over its acreage, acquired in 2015 as part of a big new 25,000 km2 regional survey. This was PSDM processed for Marathon’s acreage in early 2016, so has been made available ahead of the remainder of the survey area expected in Q3, 2016. PSDM processing of the new 3D data has significantly improved the imaging of both the pre- and post-salt sections. This enabled far more accurate interpretation of particularly the pre-salt structure, significantly improved the ability to define the best target locations and thus reduced the prospect and drilling risks. Fiscal Terms: The Gabonese fiscal terms are based on a tax, royalty formula, with full cost recovery. The Gabon State can assume a 20% interest in the block upon first production, albeit with cost recovery available under the fiscal terms. In addition, the State owned GOC has a right to acquire up to a 15% interest through the exploration phase or acquire post-exploration for up to a 10% interest based on an independently determined market price (but not both). Importantly, Marathon entered into the Tchicuate PSC (benefiting from their more favourable terms) prior to the new fiscal regime introduced in the O&G law in late 2014. As a result, scoping economics based on development scenarios, including an FPSO subsea tie back, suggest that even a modest discovery could be commercial with Tchicuate’s older licence terms, which also ensure very big upside potential if even only part of the combined newly defined estimated Tchicuate Block resource potential is confirmed by drilling. Work Programme & Obligations: The Tchicuate Block was originally awarded to Marathon in August 2014. All G&G work obligations for the initial 4 year period have been fulfilled with just the one well commitment outstanding before 2018. A well, which would require a semi-sub rig capable of operating in water depths between 800 m and up to 1,750 m, and targeting the primary plays between 2,500 and 3,000 meters (~ 8,200 – 10,000ft equiv.) below the seabed, is now estimated likely to be drilled at much more favourable cost due to rapidly declining demand in the current rig market. Marathon can declare commerciality and ring-fence any discovery made under an Exploitation Area that lasts up to 20 years from first production.

Offer: Marathon would like to find a suitable drilling partner to earn a material working interest of up to 40% based on negotiated participation in the planned drilling programme and contributions to past costs. Further Information: Access to the key data on this opportunity can be made available online after execution of a Confidentiality Agreement (CA). Serious parties will be invited for a presentation and full data review in Marathon’s offices in Houston. All expressions of interest and requests for more information, including a copy of the CA, should be made through Envoi. Contact: Mike Lakin Envoi Limited Old Stables House 1d Manor Road West Ealing London W13 0LH

T: +44 (0)20 8566 1310 E: deliver@envoi.co.uk I: www.envoi.co.uk AN ACROBAT VERSION OF THIS SYNOPSIS IS ALSO AVAILABLE FOR REVIEW ON THE ‘ACTIVE PROJECTS’ PAGE OF ENVOI’S WEBSITE

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