Challenges of Developing World-Class High Rate, High Ultimate Recovery Wells in Deepwater Turbidites — The Bonga Example
Solomon O. Inikori1, Berton Coxe1, and Jaap W. Van Der Bok2
1Bonga Development Team, Shell International E & P, Inc, Houston, TX
2OML118 Bonga Development, Shell Nigeria E & P, Company, Lagos, Nigeria
Bonga field in deepwater Nigeria represents classic deepwater turbidite reservoirs with varying degree of amalgamation. The Bonga reservoirs lie on the western flank of the shale induced Bonga Main structure. The reservoirs are Lower Upper Miocene in age, and are interpreted as stratigraphically / structurally trapped mud rich unconfined turbidite systems in a mid-lower slope setting. The reservoirs are composed of fine-grained amalgamated channel sands derived from the shelf margin to the northeast and they consist of series of amalgamated channel complexes with varying degrees of compartmentalization. This presented significant uncertainties in connected volumes, well placements and connectivity between water injector/producer well pairs. Yet another challenge in the development of these deepwater turbidite reservoirs is the need for sustainable high oil rate wells with adequate pressure maintenance. Several research studies conducted recommended that water injection wells be designed for fractured injection in order to sustain the required high rates as opposed to matrix injection. This paper presents an overview of the depositional settings of these vertically stacked reservoirs and the development concepts leading to some of industry’s sustained high rate and high ultimate recovery wells.
Also presented is an overview of the challenges of developing these complex channel deposits as well as the new approach to modeling of high rate wells in deepwater turbidites.
After over 2 years of production, average oil production rates of vertical/deviated wells still range between 15,000 to 22,000 bopd and that of horizontal wells range between 25,000 to 35,000 bopd with estimated Ultimate recovery (EUR) range from 20 to 100 mmstb. World-class water injection rates of between 40,000 to 70,000 bbls per day per well have been sustained since first oil.
AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery