Sebelumnya, kata dia, pada April 2006 MedcoEnergi dan mitra kerja Premier dan Japex Block A Ltd., anak perusahaan Japan Petroleum Exploration Co. Ltd. bersama-sama disebut Japex telah mengambilalih 100 persen saham Mobil Block A MBAL dari ExxonMobil Block A Investment Limited yang juga merupakan pemegang 50 persen hak kepemilikan di KPS Blok A.
In April 2006 MedcoEnergi as well as its partners Premier and Japan Petrolleum Exploration Co. Ltd. Japex took over 100 percent ownership of Mobil Block A MBAL from ExxonMobil Block A Investment Ltd that controlled 50 percent of the working interest of Block A.