Simultaneous Shooting, Today and Tomorrow

Since 2006 in North Africa and the Middle East, BP has faced the problem of having to evaluate and meet drilling commitments in several very large onshore exploration licences within the relatively short timeframes set by the terms of exploration license agreements. Historically, time and cost considerations would have precluded the use of 3D and large exploration areas would have been evaluated using 2D data. Our goal was to acquire simultaneous seismic source data as good as or better than conventional data while reducing the cost and time of the operation. Moving from conventional to simultaneous source acquisition has required significant changes to the way we think about seismic acquisition. For example, our usual approach of discontinuous recording of shots separated in time needs to be replaced with continuous recording with careful scheduling and recording of the location and times of all shots (Howe, et al. 2008). Reduced field effort is offset by increased processing effort and computational costs, and new processing approaches and mathematical techniques, especially those of sparse inversion and compressive sensing, will become more important in dealing with simultaneous source data. Between 2008 and 2012, BP acquired around 25,000 square kilometers of high fold wide azimuth 3D in the desert regions of North Africa and the Middle East. In every case, simultaneous source technology resulted in better data at less cost. Furthermore, less time in the field has meant a significant reduction in HSE exposure. Whilst the bulk of these wide azimuth onshore data had fold in the 500-1500 range, high channel-count crews and simultaneous source techniques now make it possible to acquire super-dense 3D data with regular ‘carpets’ of sources and receivers on a 50m*50m grid (or less). This approach resulting in 20,000 fold data, has been tested over a small focussed area for field development purposes (Howe, et al. 2009). Onshore success naturally suggests the potential for application offshore. Certain challenges need to be overcome before simultaneous source acquisition becomes more than a simple compromise between cost and quality. These new methods of acquisition have and will continue to require modifications to traditional methods of acquiring and processing seismic data.