b'the exploration phase, which ends in September 2021. There is one additional period consisting of twoyears and carries a one well drilling obligation. In the event of commercial success, the duration of thecontract will be 30 years from the effective date or 25 years from governmental approval of a plan ofdevelopment, whichever is longer.Cote dIvoire Exploration AgreementsIn December 2017, we entered into petroleum contracts covering Blocks CI-526, CI-602, CI-603,CI-707 and CI-708 with the Government of Cote dIvoire, and we are the operator. The Cote dIvoirenational oil company, PETROCI Holding (PETROCI), currently has a 10% carried interest. Thepetroleum contracts cover approximately 17,000 square kilometers, with a first exploration period ofthree years with two possible extensions of three years each. The next exploration phases are subject tofulfillment of specific work programs. The first exploration period work program includes a 12,000square kilometer 3D seismic acquisition across the five blocks.Namibia Exploration AgreementsIn September 2018, we acquired a 45% non-operated participating interest in PEL 39 offshoreNamibia. Based on the terms of the agreement we will carry Shells share of the costs of a planned 3Dseismic program subject to a cap. The Namibian national oil company, National Petroleum Corporationof Namibia (NAMCOR), currently has a 10% carried participating interest during the explorationperiod. The carry of NAMCORs 10% participation interest may continue through first commercialproduction but must be reimbursed through production. The petroleum contract covers approximately12,300 square kilometers, with an initial exploration period and two renewals periods. The block iscurrently in the first renewal period, which has been extended and expires in August 2019. A secondrenewal period of two years is available at our election, subject to fulfilling specific work obligations.The first renewal period work program has been completed.Sales and MarketingAs provided under the Jubilee UUOA and the WCTP and DT petroleum contracts, we areentitled to lift and sell our share of the Jubilee and TEN production as are the other Jubilee Unit andTEN partners. We have entered into an agreement with an oil marketing agent to market our share ofthe Jubilee and TEN fields oil, and we approve the terms of each sale proposed by such agent. We donot anticipate entering into any long term sales agreements at this time.In December 2017, we signed the TAG GSA and we began exporting TEN associated gas to shorein the fourth quarter of 2018. The TAG GSA provides for an inflation-adjusted sales price of $0.50 permmbtu.As provided under the Production Sharing Contract for Block G, we are entitled to lift and sellour share of the Ceiba Field production as are the other Ceiba Field partners. We have entered into anagreement with an oil marketing agent to market our share of the Ceiba Field oil, and we approve theterms of each sale proposed by such agent. We do not anticipate entering into any long term salesagreements at this time.In the U.S. Gulf of Mexico, we sell crude oil to purchasers typically through monthly contracts,with the sale taking place at multiple points offshore, depending on the particular property. Natural gasis sold to purchasers through monthly contracts, with the sale taking place either offshore or at anonshore gas processing plant after the removal of NGLs. We actively market our crude oil and naturalgas to purchasers, and sales prices for purchased oil and natural gas volumes are negotiated withpurchasers and are based on certain published indices. Since most of the oil and natural gas contractsare month-to-month, there are very few dedications of production to any one purchaser. We sell theNGLs entrained in the natural gas that we produce. The arrangements to sell these products first36'