operatorship. In order to complete our obligations under the petroleum contract, we will continue to fund the remainder of the current seismic program. Agadir Basin The Essaouira Offshore block is located in the Agadir Basin. A working petroleum system has been established in the onshore area of the Agadir Basin based on onshore and shallow offshore wells. Existing well data and geological and geochemical studies have demonstrated the presence of Cretaceous source rocks in the acreage. Onshore production suggests that possible Jurassic source rocks are also present in the offshore Agadir Basin. In June 2017, we completed a 3D seismic survey of approximately 3,000 square kilometers over the Essaouira Offshore Block. Additional geological studies are expected to be conducted beginning in the first quarter of 2018. The current phase of the Essaouira Offshore petroleum contract expires in November 2018. Cote d’Ivoire In December 2017, as part of our Alliance with BP, we entered into petroleum contracts as operator for five Offshore Blocks, CI-526, CI-602, CI-603, CI-707 and CI-708, which are located in a cenomanian-turonian petroleum system and range in water depth from 1,500 to 15,000 feet. The area is located approximately 150 kilometers west of our TEN discoveries in Ghana. We believe the area has multiple Cretaceous source rocks with Cenomanian through Maastrichtian reservoir sands providing exploration targets. We plan to acquire approximately 12,000 square kilometers of 3D seismic data over the blocks during 2018 to evaluate the prospectivity. Portugal In January 2017, we provided to our co-venturers a notice of withdrawal from the Ameijoa, Camarao, Mexilhao and Ostra Blocks offshore Portugal. BP Alliance During the second quarter of 2017, we formed the Alliance. This Alliance broadens the relationship that previously covered new venture opportunities in Mauritania, Senegal and The Gambia to create an Atlantic Margin explorer-developer partnership. The Alliance leverages our regional exploration knowledge and capability together with BP’s deepwater development expertise to execute a selective, joint frontier and emerging basin exploration strategy in the Atlantic Margin. Our Reserves The following table sets forth summary information about our estimated proved reserves as of December 31, 2017. See ‘‘Item 8. Financial Statements and Supplementary Data—Supplemental Oil and Gas Data (Unaudited)’’ for additional information. Our estimated proved reserves as of December 31, 2017, were associated with our Jubilee and the TEN fields in Ghana as well as our share of our equity method investment in the Ceiba Field and Okume Complex in Equatorial Guinea. Our estimated proved reserves as of December 31, 2016 and 2015 were associated with our Jubilee and TEN fields in Ghana. 23