This paper reflects back on the major trends, successes and lessons learnt of BP's 4-D deployment over the last 20 years, and offers insights into the main considerations for developing 4-D strategy in emerging areas.
Since the early 1990's, BP has been developing and deploying 4-D technologies across a range of different environments and reservoir situations. Up to the end of 2007, over 115 surveys have been acquired*, about 85 operated and 30 non-operated. This experience base represents a significant proportion of industry 4-D history, and when analysed, can offer valuable insights into developing future 4-D strategy and tactics for new fields and basins. 4-D has most commonly been used in oilfields under water-flood due to the ease of monitoring large saturation and pressure changes and the increased complexity of reservoir management, which gives the opportunity for large commercial impact. Monitoring of gas field depletion has added clear value in appropriate situations, but is much less common due to the generally simpler reservoir management issues and smaller infill programs. The dominant acquisition technology deployed has been towed streamer surveys every 25 years, but BP has now also installed the world's first three permanent ocean bottom cable (OBC) monitoring systems to deliver high-quality and frequent 3-D and 4-D data.
4-D application is continuing to expand globally, and BP itself is currently expanding 4-D application from the historical core areas of the North Sea and Gulf-of-Mexico into regions of new and existing production, such as deepwater Angola, and Alaska respectively. Development of 4-D strategies for new areas and basins requires an assessment of both technical and commercial applicability.