Spectrum has announced impressive results from the processing of the 28,000km Gulf of Mexico seismic survey using Wave Equation Migration (WEM) techniques to reveal sub-salt geology.
The 2D survey was processed at Spectrum's newly refurbished Houston data processing and imaging facility using both Kirchhoff and Wave Equation depth migration processing. Andy Cuttell, head of Spectrum's worldwide
Data Processing operations, explained their approach, "We first processed the seismic using Kirchhoff eikonal Pre-Stack Depth Migration (PSDM), which produced reliable data and revealed detail about the complex geology in the Gulf of Mexico. We then considered applying Wave quation Migration and this has paid off by revealing clearer sub-salt definition."
WEM takes into account the multiple arrivals of seismic waves in the subsurface, overcoming the limitations of standard Kirchhoff PSDM which takes into account only the first arrival of seismic waves. Compared to normal Kirchhoff migrations, the Wave Equation method increases the focusing of seismic images in areas with complex velocity models and excels in imaging below geology that is traditionally difficult to penetrate with seismic signals, such as salt formations.
Spectrum's Guillaume Richard commented, "Both Kirchhoff and WEM processing hold value to the petroleum geoscientist, because they help reveal different geological features. However, the workflow is quite different because the input for WEM consists of shot gathers. Using both techniques Spectrum has been able to learn important information on the sub-salt structure from this Eastern Gulf of Mexico data."
Impressed with the results from this survey, the Houston team also tested the WEM technique on Spectrum's "Big Wave" Phase 1 Multi Client project and concluded that it showed clear potential to improve the imaging of the Florida escarpment and the base of salt definition.