Abstract: The Deep Water ERD Challenge
Mason, Colin J. - BP Exploration Operating Co. Ltd.; Wes Black - BP Exploration Inc.
British Petroleum has continuously been at the forefront of Extended Reach Drilling (ERD), with its onshore development at the Wytch Farm oil field in Southern England and in water depths of up to 1,300 feet at the Pompano field in the Gulf of Mexico.
Ultra-deep water fields have the potential to provide a large proportion of the world?s future offshore production. It is therefore widely recognised that successful ultra-deep water exploration and subsequent cost effective field developments are essential for long term profitability. Drilling and completion costs are fundamental to overall field economics and the ability to use ERD to access deep water reserves from just one or two locations could have an immense impact on overall profitability. Some of the advantages of using deep water ERD include a reduction in high capital expense items; for example, fewer subsea tiebacks; reduced risk to the environment and a substantial decrease in future offshore well intervention costs.
Currently there is a general lack of experience in drilling highly deviated wells in ultra-deep water environments. Consequently the use and applicability of ERD techniques at these extreme depths is not at all well understood. The requirement for very long risers and the occurrence of formations that make directional work difficult results in a unique set of drilling challenges. The water depth, kick off point at which directional work can commence and the vertical depth over which all directional work must be completed are key parameters in determining zones of operability for ERD. Formation pore pressures, low fracture gradients and likely wellbore stability problems all impose additional drilling constraints. Careful mud selection and sound drilling practices will be vital in achieving good hole cleaning whilst maintaining pressures within the required operating window. However, despite these constraints there is every indication that ERD techniques could be successfully applied in ultra-deep water to access reserves within a significant drilling radius.
This poster session focuses on the feasibility of using ERD to access reserves in water depths ranging from 5,000 to 10,000 feet. Drilling constraints and areas for future technological improvements are illustrated with realistic examples. Critical design issues for ultra-deep water ERD will also be highlighted - these include drillpipe selection, wellbore profile design, hydraulic and hole cleaning requirements and the impact of riser design on drilling using SPAR and Semi-Submersible configurations.
Ultra-deep water ERD operations will also be contrasted with land based and shallower water environments. This will provide an insight into how drilling challenges change with water depth. For example at Wytch Farm, where the oil producing reservoir is located at 5,500ft TVD, a well with a departure in excess of 10km (33,000ft) was recently drilled. At the Pompano field in the Gulf of Mexico, with a water depth of 1,300ft and reservoir depth of 10,000ft TVD, wells reaching nearly 20,000ft departure have also been drilled.
At this time, experience with ultra-deep water ERD is limited. However, if techniques, innovation and learning from recent landmark wells can be successfully applied at greater water depths, implications for future drilling activities and field production will be very significant.
AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil