For more than a decade, BP has been deploying a growing range of 4-D seismic technologies, and applying these to a variety of reservoir situations. This paper reviews the "macro" view of BP's 4-D experience and offers insights into possible emerging future trends, giving a wider context to complement other IPTC papers on specific 4-D technologies.
BP has experience in about 80 operated and 30 non-operated surveys* around the world, concentrated in the North Sea and Gulf-of-Mexico (GOM). Reservoir types surveyed include clastic, carbonate and fractured under different recovery schemes, including depletion, secondary water-floods and tertiary EOR schemes. The main historical "mode" of 4-D data acquisition for BP has been with marine surface-tow streamer operations, acquired every 2–5 years. However, by the time of this presentation, BP will have installed and be operating its third permanent ocean bottom cable (OBC) seismic monitoring system.
The bulk of successful track-record to date has been in oil reservoirs under water-flood, using streamer data. Significant value has been generated through improved targeting of infill and development wells, and increasingly through improved reservoir management and reducing drilling hazards. Permanent seabed cable systems are now providing high quality wide-azimuth 3D seismic images and 'on demand' reservoir surveillance to meet the development challenges of the most complex reservoirs. Other emerging technologies include land 4-D, permanent in-well 4-D VSPs, passive seismic monitoring, and development of quantitative integration of 4-D data into reservoir models.
With 4-D now being increasingly accepted as a valuable and maturing reservoir management tool, and with many fields and projects around the world moving into the production phase, a global expansion in 4-D activity, certainly within BP, is now emerging. This will require careful deployment of the most appropriate technologies from an ever-expanding 4-D toolkit, as considered in this paper.
Over the course of the last 10–15 years, BP has helped lead the testing, development and widespread deployment of 4-D seismic technologies that are now used around a significant proportion of its worldwide asset portfolio (Figure 1). From initial investigations in the early-mid-1990's using legacy repeat 3-D surveys to investigate the possibility of detecting 4-D effects over established oil-fields, 4-D application is now considered routine in many areas with proven business value, and very often a fully integral part of field management. Early testing and deployment was dominated by the North Sea "4-D laboratory", rapidly followed by the deepwater Gulf of Mexico and now an ever-increasing expansion towards more global application to both existing (e.g. Alaska) and new and emerging production (e.g. Azerbaijan, Angola). Technologies have developed and diversified from simple marine streamer operations to now include high-spec overlapping and steerable streamers, permanent ocean bottom cable (OBC) systems, of which BP now has the world's first three systems, and the early testing of permanent in-well VSP monitoring. Processing, interpretation and integration technologies continue to evolve to ensure maximum value from the acquired data.
However, despite the major strides in the maturity and acceptance of the 4-D monitoring method, some big challenges and questions remain. Why is 4-D not used on many more fields and on different types of reservoir? Why hasn't every operator and region decided to use 4-D technology yet? What are the appropriate technologies to use? What will be the future role of 4-D monitoring in ever more efficient field exploitation and in the drive towards ultimate recovery?