discovery is to eventually tie back the Mavinga field to our Cameia project. Although we estimate
formal sanction of the Cameia project by year-end 2015 and first production from the Cameia project
in 2018 (subject to obtaining adequate financing and the approval of a revised integrated field
development plan by Sonangol and the Angola Ministry of Petroleum) those estimates and timelines do
not include any potential tie-back development to or production from our Mavinga discovery. We are
currently unable to estimate when the Mavinga discovery might be sanctioned or when we might
achieve first production. We are the operator of and have a 40% working interest in the Mavinga
discovery. Our partner in Mavinga is Sonangol P&P, with a 60% working interest.
Diaman Discovery (Diaba Block).
On August 19, 2013, we announced that the Diaman #1B
exploration well was drilled to a total depth of 18,323 feet (5,585 meters), and encountered
approximately 160 to 180 feet (50 to 55 meters) of net hydrocarbons in the objective pre-salt
formations on the Diaba Block offshore Gabon. The Diaman #1B exploration well successfully
confirmed the existence of a working petroleum system, a salt seal, and high-quality sandstone
reservoirs. We and our partners are continuing to analyze additional 3-D seismic data we acquired over
the Diaba block in 2014. The operator currently expects to resume exploration drilling on the Diaba
block offshore Gabon in 2016. Diaman is in the very early stages of the project development life-cycle
and will require substantial additional evaluation and analysis, including appraisal drilling, prior to
proceeding with any development plan. We have a 21.25% non-operated working interest in the
Diaman discovery. Our partners in the Diaman discovery include Total Gabon, as operator (42.5%
working interest), Marathon Petroleum Corporation (21.25% working interest), and the Republic of
Gabon (15% working interest).
Continued Exploration
U.S. Gulf of Mexico
We currently have several below-salt exploration prospects in the deepwater U.S. Gulf of Mexico.
Although we plan to utilize the Rowan Reliance, our only operated rig in the U.S. Gulf of Mexico,
primarily for appraisal and development work, we will continue to mature our operated below-salt
prospect inventory through seismic acquisition and evaluation and well permitting activities for future
exploration drilling. We plan to drill one to two exploration wells per year in the U.S. Gulf of Mexico,
although the order and timing of our exploration drilling is dependent on several factors and may vary
over time. Specifically, we plan to focus on maturing our Rocky Mountain Miocene prospect as well as
our South Platte, Baffin Bay, Fraser, and Williams Fork prospects, which are Inboard Lower Tertiary
prospects in close proximity to our North Platte #1 discovery. Furthermore, we may elect to participate
as a non-operator in the Goodfellow #1 exploration well, which will target Inboard Lower Tertiary
horizons. Currently we have a 21.2% working interest in the Goodfellow prospect and our partners
include ENI U.S. Operating Co. Inc. (25.7%), Samson Offshore, LLC (25.7%), and Total (27.4%).
Prior to spudding the Goodfellow #1 exploration well, the composition and working interests of the
Goodfellow partnership may change. See ‘‘Risk Factors—Risks Relating to Our Business—Our drilling
and development plans are scheduled out over several years, making them susceptible to uncertainties
that could materially alter their occurrence or timing.’’
West Africa
We also currently have several pre-salt exploration prospects offshore West Africa. Although we
plan to utilize the SSV Petroserv Catarina, our only operated rig offshore West Africa, primarily on the
appraisal and development of our existing discoveries, we plan to continue maturing up to 20 follow-on
oil-focused exploration prospects on Blocks 20 and 21 offshore Angola. We plan to continue our
exploration efforts offshore West Africa, although the order and timing of any exploration drilling is
dependent on several factors and may vary over time. See ‘‘Risk Factors—Risks Relating to Our
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