USA: CGGVeritas Conducts GoM Survey with Newly Introduced StagSeisTM
CGGVeritas is launching StagSeisTM, a “next-generation” solution for subsalt imaging, and is currently employing this technique to acquire its IBALT 5,150km2 full-azimuth survey in the Keathley Canyon area of the Gulf of Mexico.
StagSeis is designed to reduce exploration and production risk by providing innovative illumination for the best seismic images in the most challenging areas, where conventional wide-azimuth acquisition fails to image targets below complex overburdens. It employs a patented, staggered multi-vessel design acquisition configuration producing ultra-long offsets (up to 20km) and full-azimuth coverage (up to 10km) for improved illumination. It is BroadSeisTM-compatible, adding enhanced frequency bandwidth, which will further improve deep imaging. Our wide-azimuth processing expertise and state-of-the-art subsalt imaging technology ensure the best possible resolution of the subsurface using this new acquisition design.
StagSeis has been developed in response to the challenges facing our clients in complex areas such as the Gulf of Mexico, requiring longer offsets, full azimuth and broad bandwidths (especially low frequencies) to provide better illumination, multiple attenuation and signal-to-noise ratio, as well as improved velocity modeling. It can be used in areas where large-scale full-azimuth acquisition is desirable, e.g. subsalt and sub-basalt, etc., and is especially suited to large-scale multi-client surveys to reduce costs for individual oil companies. In addition, the solution can also be adapted for shallower targets where ultra-long offsets are not required, but where full-azimuth data is beneficial, making the method suitable for use in many areas worldwide.
Being fully compatible with BroadSeis variable-depth streamer acquisition, StagSeis can provide in excess of six octaves of signal, adding enhanced low frequencies to further improve deep imaging and to provide more quantitative inversion results. BroadSeis proprietary deghosting is fully 3D and applied in image space, so it avoids 2D assumptions which may compromise results in areas of complex structure; for full-azimuth surveys CGGVeritas will be able to capitalize on its recent success at acquiring and processing wide-azimuth BroadSeis surveys with excellent results. The broad bandwidths achieved using BroadSeis have already been shown to provide clearer and easier interpretation from high-resolution imaging of sharp wavelets without sidelobes as well as easier identification of sedimentary packages and stratigraphic details.
Due to its innovative staggered vessel configuration, StagSeis can provide full-azimuth coverage and the longest available offsets using a linear tow in two orthogonal passes. The linear tow provides many advantages, as it means that the fold, offset and azimuth distribution are regular and consistent from bin to bin, providing a stable stack response. The field data are available immediately after acquisition and are fully compatible with conventional wide-azimuth processing techniques for faster turnaround times, as well as being easily scalable for high-density field development surveys and repeatable for 4D. We expect to see initial results from a priority area of the current Gulf of Mexico StagSeis survey this Fall. The full acquisition is expected to be completed in early 2013, with the Fast Trax data volume being available three to five months after the final shot and the final TTI RTM results available before the end of 2013. We anticipate that this survey, known as IBALT, will be only the first phase in a multi-client StagSeis program in the Gulf of Mexico that CGGVeritas will conduct over the next few years.
The combination of full azimuths, long offsets and broad bandwidths translates into better subsalt imaging by illuminating shadow zones and steep dips, improving noise and multiple attenuation and providing more accurate velocity models to provide the best possible images below complex overburdens, at the same time as extremely high-resolution shallow data for drilling hazard identification and accurate velocity model building. The ultra-long offsets and low frequencies are the perfect combination for Full Waveform Inversion, making StagSeis the ideal complex imaging solution.
Matthew Bognar, Senior Vice President, Multi-Client & New Ventures, CGGVeritas, said: “IBALT represents a new frontier, not only for CGGVeritas but for our clients as well. Our StagSeis solution is a direct result of interaction with our clients; the message was clear – they want long offsets, full azimuth, and broadband frequencies. After studying the challenge carefully with our clients, we are now extremely pleased to be able to offer an advanced technology that addresses our clients’ needs through our IBALT survey. We are delighted with our progress on the IBALT survey, having acquired over half the survey in a significantly shorter time than originally anticipated. We have begun processing and eagerly await results of both the Fast Trax and fully processed products.”
Press Release , November 05, 2012