The exploration targets beneath thick layers of salt are examples of complex geological environments that require the use of innovative imaging methodologies which can bring improvements in image quality and hence better definition of subsurface layers. Reverse Time Migration is a PSDM method that propagates the source wave field forward and the recorded wave field backwards in time, using the two-way hyperbolic wave equation. Its main advantage over one-way wave equation techniques is that it has virtually no dip limitation and handles all complex waveform multipathing.
RTM is recognized as the best technique for imaging salt tectonics environments and layers with high slopes. Traditional methods for forward modeling, involving finite differences in space and time are extremely time consuming, which requires the use of supercomputers, particularly with 3D data.
To address the computational cost of RTM and provide a solution, which is viable before the industry’s demand, the computational geophysics research group of PETREC has been working in partnership with NACAD, the high-performance computing group of COPPE, for over 12 years.
- Travel Time, Convolutional and basic cross-correlation imaging conditions
- High level I/O in order to store forward wave fields
- Low memory requirement
- Optimized back propagated wave field calculation
- High order and optimized finite difference operators
- Optimized computational grids
- Optimized for high performance computing environment
- Isotropic and Anisotropic (VTI & TTI), 2D and 3D solutions
- Highly efficient absorbing boundaries (CPML)
- Shot parallelization and domain decomposition high level techniques
- Easily integrated with several seismic processing platforms.