Reverse Time Migration






Really Fast Results with AxRTM


Reverse Time Migration (RTM) is an advanced migration method for seismic depth imaging. The strength of RTM stems from the fact that it fully respects the two-way acoustic wave equation, thus improving imaging in areas where complex geology violates the assumptions made in Kirchhoff or one-way wave equation migrations. Until recently, RTM’s widespread use was severely hindered by the enormous computing resources required to process the data. This computational bottleneck is now cleared with Acceleware’s AxRTM™ solution.

AxRTM provides the core numerical functionality of Reverse Time Migration as a library that can be integrated into an existing seismic processing framework. AxRTM has a modular architecture supporting a variety of integrator-specific functionality, and currently supports both optimized multi-core CPU and NVIDIA GPU hardware.

Cost Effective RTM Angle Gathers

In complex geology, traditional RTM offset-domain common image gathers (ODCIG) suffer from artifacts due to multiple paths of wave propagation around complicated structures. The CIGs indexed by subsurface reflection angle suffer much less from migration artifacts for complicated structures, however early implementations of RTM angle gathers have been cost prohibitive. AxRTM’s efficient implementation of true-amplitude ADCIG (in 2D or 3D simulations) can now be used for migration velocity model updating and amplitude versus angle (AVA) analysis. AxRTM’s angle gathers provide a powerful and cost effective tool for validating and improving earth models in complex geology such as beneath salt bodies or gas clouds or in fractured zones.

Features and Specifications

Below lists major components of the AxRTM library. The architecture of AxRTM is designed to allow for the addition of geophysical functionality in a modular fashion. This allows an Integrator who has their own RTM expertise to incorporate their proprietary methods above and/or into the API.

Wavefield Propagation
  • Optimized CPU and GPU
  • High order finite-difference solver
  • Isotropic acoustic
  • Anisotropic
    • VTI (Vertical Transverse Isotropy)
    • TTI (Tilted Transverse Isotropy)
    • Standard and Enhanced Stability formulations for VTI and TTI
  • Dispersion-minimizing finite-difference stencil
  • Grid optimizations reduce memory and compute time

Imaging Condition

  • Basic cross-correlation
  • Noise-reducing imaging condition
  • Laplacian imaging condition
  • High frequency ICC imaging condition

Source Wavefield Access for Correlation

  • High performance and low storage requirements, without loss of fidelity
  • No high throughput storage technology required; local SATA works well even with accelerated AxRTM
  • Multiple storage methods allow balancing of compute and IO
Workflow Integration
  • C-API for maximum flexible product integration
  • Compute hardware abstraction provides “geophysical development focus”

Boundary Conditions

  • Sponge (Israeli-Orszag)
  • CPML - Convolutional Perfectly Matched Layer
  • Perfectly reflective
  • Taper

Domain Decomposition

  • Support optimized for latest multi-core, multi- socket Intel and AMD processors
  • Support for multiple GPUs on a single compute node (maximum of 4 GPUs recommended)
  • Support for single shot computed by multiple CPU or GPU nodes using MPI or TCP sockets
  • Efficient scaling across multiple devices and nodes

Illumination Calculation

  • (Optional) source illumination calculation performed during the forward pass
  • Illumination information can be used for amplitude scaling of the migrated image volume

Currently supported hardware is Intel/AMD multi-core CPU and NVIDIA GPUs. Support for future computational hardware was part of the fundamental design of the AxRTM library, meaning that adopting a new hardware platform in the future will not require any changes to the overlying RTM application.


The Importance of Anisotropic Reverse Time Migration

Move the mouse over the picture to show how isotropic imaging of this anisotropic dataset fails to image the salt flanks and mis-positions the sub-salt sediments. In the TTI image, the salt flanks are clearly defined and the sediments imaged right up to the salt boundary.


Domain Decomposition

For large RTM volumes, AxRTM decomposes the domain across multiple compute nodes. Acceleware fully supports the spanning of a single migration volume across both multiple GPUs/CPUs on a single compute node, as well as multiple compute nodes (Figure 1).

Figure 1: Compute nodes are dynamically grouped into Shot Groups to work on very large migration volumes.


Buy - Ready to Run

Purchase your production ready RTM application including the AxRTM library from our distribution partners: Paradigm Geophysical, Tsunami Development, Open Geophysical or GeoTomo. These proven end-to-end solutions are ready to run today.

Customized RTM Solution

Using the AxRTM library as the computational engine Acceleware can build and integrate an RTM solution to meet your needs. This provides a tailored solution that integrates seamlessly with your existing processing workflow. Please contact an Acceleware representative for more information.

Acceleware RTM Layer Model