The decline of conventional seismic acquisition and the rise of specialized acquisition: this is compressive sensing Christof Stork* & David Brookes, ION Geophysical Summary Many seismic acquisition surveys today have some form of customization and specialization to reduce cost, address operational issues, or efficiently resolve a difficult geologic objective. This trend has been clearly aided in the recent past by the following: 1) Acquisition systems are more flexible and provide capability to specialize, 2) Geologic and reservoir objectives are getting more demanding and diverse, and 3) Geophysicists have more experience and expertise with acquisition opportunities. This trend of specialized acquisition will probably accelerate in the future because of: 4) Better processing tools that allow for very irregular and non-uniform acquisition, & 5) New processing tools that benefit from specialized acquisition, and 6) Better risk management tools by companies to accept unconventional acquisition. The recent discussions on “compressive sensing” shares strong parallels with specialized acquisition. Both perspectives try to find the best acquisition compromise between cost, geologic resolution, noise, and operational restrictions. Both perspectives rely on using advanced processing for successful imaging with unconventional acquisition. Modifying seismic acquisition based on the performance of new processing tools adds risk and should be done cautiously for this expensive process. But, there is a lot to be gained from finding the best acquisition compromise. Not only can costs be significantly lower, but key geologic & reservoir objectives can be resolved. The new processing methods significantly alter the considerations for the best compromise. Better risk management consideration by companies and some new aggressive risk analysis tools will aid the adoption of these specialized, unconventional acquisition & processing approaches. Introduction Conventional acquisition is often designed using criteria of a regular acquisition pattern and minimizing near offset holes to improve shallow imaging. These criteria greatly simplify processing and reduce potential acquisition artifacts that may not be fixable in processing. Moreover, since the new processing methods are more sensitive to noise, considering noise is crucial and should play a large role in acquisition design. It is surprising that acquisition does not vary more around the world given that geologic objectives, seismic noise, and operational constraints vary dramatically around the world. We define conventional approaches as land cross-spreads and marine NAZ/WAZ surveys. These conventional patterns may be modified, but the basic pattern is the basis of many acquisition surveys around the world. Lifting the criteria of a regular acquisition pattern and minimizing near offset holes allows for much, much greater acquisition flexibility. This flexibility can be used to reduce costs, improve azimuth/offset coverage, improve converted wave illumination, optimize complex structure illumination, or reduce noise. These can each be big things. Examples of using this acquisition flexibility to specialize seismic surveys are: 1) Irregular OBC layout to optimize illumination sub-salt; 2) Circular shooting to increase azimuth and offset coverage for sub-salt; 3) Simultaneous or fast dithered sources 4) Using distributed 2D digital arrays on land to damp surface noise; 5) Acquiring converted waves for improved reservoir inversion; and 6) Enabling interferometric acquisition during non- shooting time. The new processing methods that allow for the additional acquisition flexibility are: a) Improved interpolation and regularization methods b) FWI for determination of near surface velocities c) Several types of iterative methods that eliminate the impact of acquisition irregularity d) Flexible multiple prediction and removal methods A key challenge with specialized acquisition is addressing the risk. Because of their cost, time of planning/acquisition/processing, and senior management involvement, acquisition surveys should have low risk. The desire for low risk encourages using proven conventional survey designs. However, by using aggressive risk analysis tools, the risk for specialized surveys can be greatly reduced. Page 4386 SEG Denver 2014 Annual Meeting DOI http://dx.doi.org/10.1190/segam2014-0870.1 © 2014 SEG Main Menu T