Exploration in the Ceará basin, on the south-western part of the Equatorial Margin of Brazil, commenced in the early 1970s. Several moderate size fields such as Xaréu, Curimã, Atum, and Espada fields, with URR volume of around 200 MM BOE, were discovered on the shelf and are producing to this day. Exploration in the deep water part of the basin has been sparse (only 5 wells in water depth greater than 1000 m to date) with some success but, most importantly, de-risked the working petroleum system. With significant part of the deep water acreage licensed to operators in the 11th bid round in 2013, the basin is now embarking on a new exciting phase of exploration.

Ceará basin sedimentary fill is divided into three mega-sequences: syn-rift, transitional and drift. The basin is blessed with world-class source rocks of Aptian to Turonian age developed within all three main megasequences.

The Transitional megasequence contains both the source rocks and the reservoirs. This play was tested by the Pecem discovery in 2012 by Petrobras on the flank of a large structural high. Reservoir quality and connectivity remain the main uncertainty for this play. Other plays include a structural play with reservoirs in the syn-rift sandstones (Mundaú formation), and the Upper Cretaceous turbidite slope channel/canyons. In addition, in the outboard blocks onlap wedge plays in the Transitional early lower part of the drift megasequence have been identified. These plays could be analogous to the successfully tested plays on the conjugate margin in West Africa.

Premier Oil plc (Premier) and partner CEPSA have won two exploration licenses (Blocks CE-M-717 and CE-M-665) in the 11th bid round and are now the dominant acreage holders in Ceará basin. The Premier JV has reprocessed two existing 3D surveys resulting in an improved definition of both the syn-rift and drift section and imaging of new prospects and leads. A multi-client 3D survey using broadband technology is planned for 2015 which is expected to result in a superior seismic image in time for impacting the exploration drilling programme in 2017.

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