b'KOSMOS ENERGY LTD.Supplemental Oil and Gas Data (Unaudited)Net proved oil and gas reserve estimates presented were prepared by Ryder Scott Company, L.P.(RSC) for the years ended December 31, 2018, 2017 and 2016. RSC are independent petroleumengineers located in Houston, Texas. RSC has prepared the reserve estimates presented herein andmeet the requirements regarding qualifications, independence, objectivity and confidentiality set forthin the Standards Pertaining to the Estimating and Auditing of Oil and Gas Reserves Informationpromulgated by the Society of Petroleum Engineers. We maintain an internal staff of petroleumengineers and geoscience professionals who work closely with our independent reserve engineers toensure the integrity, accuracy and timeliness of data furnished to independent reserve engineers fortheir reserves estimation process.Net Proved Developed and Undeveloped ReservesThe following table is a summary of net proved developed and undeveloped oil and gas reserves toKosmos interest in the Jubilee and TEN fields in Ghana, the U.S. Gulf of Mexico (commencingSeptember 14, 2018, the DGE acquisition date), and our equity method investment offshore EquatorialGuinea.Equity MethodInvestmentEquatorialKosmos Entities GuineaOil Gas Total Oil Gas Total Total(MMBbl) (Bcf) (MMBoe) (MMBbl) (Bcf) (MMBoe) (MMBoe)Net proved developed and undevelopedreserves at December 31, 2015(1) . . . . 74 14 7676Production . . . . . . . . . . . . . . . . . . (7) (1) (7)(7)Revision in estimate(2) . . . . . . . . . . 7 2 88Net proved developed and undevelopedreserves at December 31, 2016(1) . . . . 74 15 7777Extensions and discoveries . . . . . . . . 111Production . . . . . . . . . . . . . . . . . . (11) (1) (11) (1)(1) (12)Revision in estimate(3) . . . . . . . . . . 18 35 2424Purchases of minerals-in-place(4) . . . .20 13 21 21Net proved developed and undevelopedreserves at December 31, 2017(1) . . . . 82 49 89 19 13 21 110Extensions and discoveries . . . . . . . . Production . . . . . . . . . . . . . . . . . . (13) (3) (14) (5)(5) (19)Revision in estimate(5) . . . . . . . . . . 11 (1) 11 10 1 10 21Purchases of minerals-in-place(6) . . . . 47 40 5454Net proved developed and undevelopedreserves at December 31, 2018(1) . . . . 127 85 141 24 14 26 167Proved developed reserves(1)December 31, 2016 . . . . . . . . . . . . . 64 13 6666December 31, 2017 . . . . . . . . . . . . . 59 38 65 18 13 20 85December 31, 2018 . . . . . . . . . . . . . 81 57 91 23 14 25 116Proved undeveloped reserves(1)December 31, 2016 . . . . . . . . . . . . . 10 2 1111December 31, 2017 . . . . . . . . . . . . . 23 11 24 11 25December 31, 2018 . . . . . . . . . . . . . 45 28 50 11 51(1) The sum of proved developed reserves and proved undeveloped reserves may not add to net proved developedand undeveloped reserves as a result of rounding.(2) The increase in proved reserves is a result of an 8 MMBbl increase associated with positive revisions to the TENfields as a result of the completion of seven wells along with the initiation of TEN production partially offset by1 MMBbl of negative revisions to the Jubilee Field due to decreased pricing.152'