News Release Details

KOSMOS ENERGY ANNOUNCES SUCCESSFUL COMPLETION OF
TORTUE DRILL STEM TEST

DALLAS, Texas, August 23, 2017 - Kosmos Energy (NYSE: KOS) announced today that it has successfully completed the drill stem test (DST) of the Tortue-1 well, demonstrating that the Tortue field is a world-class resource and confirming key development parameters including well deliverability, reservoir connectivity, and fluid composition.

The Tortue-1 well flowed at a sustained, equipment-constrained rate of approximately 60 million cubic feet per day (MMcf/d) during the main, extended flow period, with minimal pressure drawdown, providing confidence in well designs that are each capable of producing approximately 200 MMcf/d. The DST results confirmed a connected volume per well consistent with the current development scheme, which together with the high well rate is expected to result in a low number of development wells compared to equivalent schemes. Initial analysis of fluid samples collected during the test indicate Tortue gas is well suited for liquefaction given low levels of liquids and minimal impurities. Data acquired from the DST will be used to further optimize field development and to refine process design parameters critical to the front end engineering and design (FEED) process anticipated to begin later this year.

"The positive results from the DST confirm that the Tortue field is a world-class resource and validates the assumptions that underpin our development concept" said Andrew G. Inglis, chairman and chief executive officer.  "The combination of high well rates, large connected volume per well together with a gas well-suited for liquefaction is why we believe Tortue is one of the lowest cost pre-FID greenfield LNG projects. The Kosmos BP partnership remains aligned on delivering a final investment decision for the project in 2018 and first gas in 2021."

The Tortue-1 well is located in water depths of approximately 2,700 meters offshore Mauritania.  The DST was conducted by the Atwood Achiever drillship, which has now mobilized to the Hippocampe prospect in Block C-8 offshore Mauritania to begin exploration drilling operations.

Kosmos is exploration operator of Block C-8 with a 28% participating interest. BP is named operator with a 62% participating interest, and Societe Mauritanienne des Hydrocarbures et de Patrimoine Minier ("SMHPM") has a 10% participating interest.

About Kosmos Energy

Kosmos is a leading independent oil and gas exploration and production company focused on frontier and emerging areas along the Atlantic Margin. Our assets include existing production and development projects offshore Ghana, large discoveries offshore Mauritania and Senegal, as well as exploration licenses with significant hydrocarbon potential offshore Suriname, Sao Tome and Principe, Morocco and Western Sahara. As an ethical and transparent company, Kosmos is committed to doing things the right way. The Company's Business Principles articulate our commitment to transparency, ethics, human rights, safety and the environment. Read more about this commitment in the Kosmos 2016 Corporate Responsibility Report. Kosmos is listed on the New York Stock Exchange and is traded under the ticker symbol KOS. For additional information, visit www.kosmosenergy.com.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements, other than statements of historical facts, included in this press release that address activities, events or developments that Kosmos expects, believes or anticipates will or may occur in the future are forward-looking statements. Kosmos' estimates and forward-looking statements are mainly based on its current expectations and estimates of future events and trends, which affect or may affect its businesses and operations. Although Kosmos believes that these estimates and forward-looking statements are based upon reasonable assumptions, they are subject to several risks and uncertainties and are made in light of information currently available to Kosmos. When used in this press release, the words "anticipate," "believe," "intend," "expect," "plan," "will" or other similar words are intended to identify forward-looking statements. Such statements are subject to a number of assumptions, risks and uncertainties, many of which are beyond the control of Kosmos, which may cause actual results to differ materially from those implied or expressed by the forward-looking statements. Further information on such assumptions, risks and uncertainties is available in Kosmos' Securities and Exchange Commission ("SEC") filings.  Kosmos undertakes no obligation and does not intend to update or correct these forward-looking statements to reflect events or circumstances occurring after the date of this press release, except as required by applicable law. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release. All forward-looking statements are qualified in their entirety by this cautionary statement.

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CONTACT:

Investor Relations

Neal Shah

+1-214-445-9628

nshah@kosmosenergy.com

Rhys Williams

+1-214-445-9693

rwilliams@kosmosenergy.com

Media Relations

Thomas Golembeski

+1-214-445-9674

tgolembeski@kosmosenergy.com