Drilling Akpo: 22 Wells Required, 22 Wells Delivered For Production Start Up and Plateau
Authors: Ludot Benoit , Delattre Eric 
Published: July 2010

Akpo field is located in block OML 130, 200 km offshore Nigeria in 1400 m water depth. At plateau production, Akpo produces 175,000 bbls/day of condensate and exports 320 mmscfd of gas to Bonny NLNG plant. It is the first Deep Offshore development for TOTAL in Nigeria, soon to be followed by Usan in OPL 222 and Egina in OML 130

TOTAL, with 24% interest, is the Operator on OML 130 on behalf of Petrobras of Brazil, Sapetro of Nigeria, CNOOC of China and NNPC of Nigeria.

Akpo reservoirs consist in a 620 million barrels recoverable reserves of a critical fluid made of very light oil up to 53° API and classified as condensate, with wellhead shut-in pressures up to 400 bars, wellhead temperatures up to 116 °C and very high GLR (Gas Liquid Ratio).

Reservoir management requires massive pressure maintenance facilities and extensive use of intelligent and selective completions.

Akpo achieved first production on 4th March, 2009, ahead of schedule, and completed the ramp-up of all the facilities within only 3.5 months from the initial start-up date.

The paper addresses the well construction of AKPO development from the project preparation to the production start up and in particular presentsThe leading edge deep offshore well architectures designed to meet the production objectives in such high pressure and temperature conditions.The drilling plan implemented to meet the aggressive target of 22 wells to be delivered for the production plateau.The operation support and organization put in place for the first deep offshore development drilling campaign of Total in Nigeria.The achievements, the operational difficulties and how they have been addressed, and finally the lessons learned from the first 22 well drilling phase.

AKPO DEVELOPMENT

Akpo plateau production is 175,000 bpd of condensates and 550 mmscfd of produced gas, with 320 mmscfd exported to Bonny NLNG plant, 220 mmscfd re-injected and the remainder used as fuel gas. Akpo is therefore a giant condensate field with estimated 620 Mbbls reserves, but also a gas field with 1Tcf planned export gas.

Akpo is a standalone development based on a spread moored Floating Production Storage and Offloading (FPSO) with a storage capacity of 2 million barrels of condensate. The stabilized condensate is exported via offloading lines and a deep water buoy located 2 km away from the FPSO.

A total of 44 subsea wells (22 producers, 20 water injectors, and 2 gas injectors) will be drilled in dispersed and clustered subsea architecture.

In total, there are 110 km of subsea flowlines connected to the surface production facilities by 14 steel catenary risers. The subsea network comprises 4 production loops, 1 gas injection line, 4 water injection lines, 1 gas export line. It is connected from 10 manifolds installed on the seabed. The water injection wells are connected using " In Line tee?? pieces in various locations along the water injection flowlines.

Akpo achieved Project sanction on 25th April, 2005 when OML 130 was awarded by the Nigerian authorities. Akpo first gas production occurred on 4th March 2009. The production plateau of 17500 bpd was reached in September 09.