ION's Reverse Time Migration Expedites Delivery of Subsurface Images

ION Geophysical Corporation announced that its GX Technology (GXT) Imaging Solutions group has made significant improvements in their reverse time migration (RTM) technique. GXT has extended RTM for use in the rapidly growing segment of complex azimuth marine acquisition and has simultaneously reduced the turnaround time to deliver RTM-derived subsurface images to its oil & gas company customers.

Nick Bernitsas, Senior Vice President of ION's GXT Imaging Solutions group, commented, "Almost every oil & gas company agrees that RTM is the depth migration technique that is capable of delivering seismic images of the highest quality and integrity, especially in structurally complex areas or when imaging reservoir targets that are located beneath salt. Historically, oil & gas companies were forced to make a tradeoff between the improved image quality that RTM can provide and the increased cycle time associated with utilizing an RTM-based approach.

With the proprietary enhancements GXT has made to RTM implementation, we have eliminated that tradeoff. Now, our clients can obtain RTM-derived images in the same amount of time it would take to depth migrate the data using other commonly accepted methods, such as wave-equation migration (WEM). This enhances the value of the RTM imaging technique and, we believe, allows our customers to increasingly utilize GXT RTM for their most critical, time-constrained seismic imaging projects, including surveys that were acquired using complex azimuth geometries."

Mr. Scott Heck, Senior Vice President of E&P Technology at Hess Corporation, added, "Hess is committed to the application of appropriate state-of-the art technologies. Given the geologic challenges that we face in the deep water Gulf of Mexico subsalt environment, Hess was pleased to serve as GXT's first commercial customer when they launched RTM in 2005. The technique has proven to be valuable, and the recent improvement that GXT implemented will increase the value of the product by reducing turnaround time. I am excited about what this might mean for Hess' exploration and development programs in the Gulf of Mexico, West Africa and Brazil, among other areas."

RTM works by running the seismic wave equation forward in time for the source and backwards in time for the receiver. RTM overcomes the compromising assumptions of other depth migration methods by properly propagating acoustic wave fields through the most complex velocity regimes, including sub-salt, for structures having dips in excess of 90 degrees, and in the presence of reflection boundaries that may generate internal multiples.

Although RTM is not a new concept, its application has been limited by the ability to execute the RTM algorithms cost effectively and in a timely manner. GXT has overcome these constraints and has completed nearly 30 RTM projects for clients around the globe, including in the Gulf of Mexico, West Africa, and the North Sea. In addition, GXT has implemented RTM for wide-azimuth (WAZ) acquisition geometries, on full-wave (multicomponent) imaging projects, in the presence of anisotropy, and as part of vertical seismic profiles (VSPs).