The adoption rate of optical sensing technology for in-well permanent monitoring has accelerated dramatically since first introduced more than 10 years ago and a number of optical sensor types, including pressure, temperature, distributed temperature, seismic, and flowmeters have been commercialized. Although optical sensing technology has a demonstrated track record and gained industry acceptance, large-scale, field-wide commercial deployment has been slow.
This paper describes a recent example of field-wide optical sensing deployment with a planned scope of 27 wells. Multiple in-well sensors were installed in the newly developed Buzzard Field, operated by Nexen Petroleum U.K. Limited in the North Sea. This paper explores the initial results after the first 13 well completions. An assessment of the major project phases from definition, planning, and system selection to project execution, site integration testing, installation, and early life operation of the optical technology is included. A number of lessons in equipment and system design, execution, and data management have been learned and are also discussed in the paper. Whilst field development is ongoing, the initial success rates show that satisfactory performance has been obtained in all key areas including data availability, delivery, and post-processing.
This case study demonstrates that innovative optical sensing technology and downhole flow measurement is ready for large-scale adoption with minimal risk. This is an important and timely finding as the industry is introducing optical monitoring into large subsea fields.
Acknowledgements
The authors gratefully acknowledge Nexen Petroleum U.K. Limited and Weatherford Intl. as well as the Buzzard Field partners PetroCanada Energy North Sea, BG Group, and Edinburgh Oil & Gas Limited, for permission to publish this work. They would also like to acknowledge the efforts of coworkers in Nexen Petroleum U.K. Limited and Weatherford Intl. in the planning, installation, commissioning, and performance evaluation stages. This paper has been jointly prepared by Nexen Petroleum U.K. Limited and Weatherford Intl. for presentation at the SPE Intelligent Energy Conference Amsterdam, 25–27 February 2008. Neither the authors nor their employers shall be liable for any reliance on its contents.
Background
Since the introduction of fiber-optic based reservoir monitoring systems in 1993 the adoption rate has increased dramatically. Today, most of the common electronic based technology measurements for in-well permanent reservoir monitoring have a commercially available optical equivalent, such as pressure & temperature, and seismic sensors. In fact, optical monitoring has not only equaled but added further functionality to the previously available monitoring toolset through Distributed Temperature Sensing (DTS) and non-intrusive single- and multiphase flowmeters. Currently, the only area that the optical sensing has not penetrated into is the subsea application.
Functionally, optical sensing offers a viable alternative to traditional methods of in-well permanent monitoring. However, it has not yet made significant leaps in volume deployment in comparison with these traditional methods. In 2004, this situation changed when Nexen Petroleum U.K. Limited (formerly EnCana) and its partners PetroCanada Energy North Sea, BG Group and Edinburgh Oil and Gas, awarded the Permanent Downhole Monitoring System (PDMS) contract covering the Buzzard field. It was a technologically bold decision to go for an all optical in-well reservoir monitoring system for the Buzzard field development.
