AKPO: A Giant Deep Offshore Development

Summary All deep water offshore projects are challenging. They are large developments, difficult to implement and often beyond the limits of proven technologies at their inception. AKPO field is located in block Offshore Mining License (OML) 130,200 km offshore Nigeria in 1400 m of water. At plateau production, AKPO will produce and export 175,000 B/D of condensate and will export, at startup, 320 MMscf/D of gas to Bonny NLNG plant, onshore Nigeria. AKPO reservoirs characteristics have greatly influenced the development scheme while still making it technically and economically viable. AKPO reservoirs consist in a 620-million-recoverable-barrels accumulation of a critical fluid made of very light oils up to 53°API and classified as condensate, with well head shut-in pressures up to 400 bars, fluid temperature up to 116°C at wellhead, and very high gas liquid ratio (GLR). AKPO is not only a giant condensate field, but also a gas field with 1 Tcf planned gas export. With such particular reservoir conditions, the AKPO development scheme is very challenging and maximizes the use of proven and generic technologies whenever possible. The development is taking place at a time when the supplier market is very buoyant. This, in turn, has created additional challenges with respect to the availability of skilled resources and obtaining quality products on time. The paper addresses the challenges of AKPO development and in particular some of the key technical issues. A unique hybrid condensate production/gas export development scheme which maximizes hydrocarbon recovery Reservoir management requiring massive pressure maintenance facilities, extensive use of intelligent and selective completions, and subsea multiphase flow measurements A development drilling strategy and well architecture. A subsea layout compromise, aiming at maximum reliability and availability. Extensive qualification and testing program of equipment to meet with the reservoir conditions. An FPSO concept pushed to the limit to handle high volume of high-pressure (HP) fluids together with a very large gas inventory. The securing of resources in terms of dry dock slot, marine spread and deep offshore drilling units in a buoyant market. TOTAL, with 24% interest, is the operator on OML 130 on behalf of Petrobras of Brazil, Sapetro of Nigeria, China National Offshore Oil Corporation of China (CNOOC), and Nigerian National Petroleum Corporation (NNPC) of Nigeria. AKPO achieved Project sanction on 25 April, 2005, when OML 130 was awarded by the Nigerian authorities. AKPO is currently under development with drilling and construction underway, with first production planned before the end of 2008.