Fraunhofer Institute for Industrial Mathematics ITWM
Fraunhofer Institute for Industrial Mathematics ITWM
RTM
© ITWM
RTM

RTM for elastic anisotropic Earth's subsurface:

RTM (reverse time migration) is a wave equation based migration method that is applicable even in case of very complicated subsurface structures.

© ITWM

Seismic Depth Migration RTM

Seismic depth migration algorithms calculate images of the Earth's subsurface from the measured and pre-processed seismic reflection data. These images deliver important pieces of information to the geoscientist for discovering oil and gas reservoirs. The method of reverse time migration (RTM) stands out by high imaging quality even in case of high geological complexity. Solving the wave equation (rather than high-frequency approximations to this equation) realistically simulates the propgation of waves through the subsurface and allows the exact imaging of structures with strongly contrasting seismic velocities as they occur, e.g, for salt bodies.

We recommend to apply RTM in addition to GRT for combining high structural imageing quality with true amplitudes imaged at target horizons.

RTM Single Shot Scalability
© ITWM
RTM Single Shot Scalability
Asynchronous Constraint Execution
© ITWM
RTM is integrated in our ACE (Asynchronous Constraint Execution) Framework.

By using proprietary HPC tools we obtain a massively parallel and robust implementation of RTM that combines the necessary degree of accuracy with ultimate efficiency. Our particulary designed random perturbation boundary conditions make the software free of any I/O of intermediate results that would typically be of multi-TeraByte scale for each of the 10000s of shots. This I/O is quite often a major reason why other implementations fail in computing large scale problems. We use fully optimized finite difference stencils of various order for solving the wave equation for isotropic, VTI, and TTI velocity models. Our RTM is integrated into ACE (Asynchronous Constraint Execution) framework.
 

High parallel efficiency due to ACE:

Due to fine-granular decomposition of the migration output volume and the dynamic assignment of partial jobs of the total migration job to the cores of the compute cluster we achieve an extremely high parallel efficiency and, thus, nearly perfect scalibilty of the migration even for such extreme cases as running a single shot migration on many thousands of computes cores. The allocation of compute resources
to the complete migration job can be done dynamically, i.e. compute nodes can be added or removed during runtime of the migration - this flexibility is highly desirable in production environments.

Adaptive stacking of single shot migration results optimizes the signal/noise ratio. We offer RTM in 3D, but also have an optimized 2D version. Our RTM can also run in forward modelling mode. For this application, the random pertubation boundary condition is replaced by absorbing boundary condition and the user can specify source-receiver layout with a high degree of flexibility.

Related Links: