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Thursday, March 5 • 11:25 - 11:45
Fine-grained Seismic Algorithms: “RiDG: A Portable High-Performance Simulation Tool for Seismic Imaging,” Axel Modave and David Medina, Rice University; Amik St-Cyr, Shell; Tim Warburton, Rice University

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Improving both the accuracy and computational performance of simulation tools for seismic imaging is a major challenge for the Oil and Gas industry. The current generation of compute clusters consist of many-core CPU and optionally massively parallel graphics processing units or side-car accelerators to provide a performance boost. However, acceleratoraided clusters require specialized algorithms and simulation tools to make full use of the hardware (e.g. [1, 4, 7]).

RiDG is the result of a collaboration between research teams at Rice University and Shell. It was conceived as a high-performance tool for seismic migration that can be run on several hardware architectures. It includes reverse time migration (RTM) capabilities, and multiple wave models on both heterogeneous and anisotropic media.

The model solver is based on a nodal discontinuous Galerkin time-domain (DGTD) method with high-order basis functions. The weak element-to-element coupling of DGTD methods makes it a suitable scheme for efficient computations on modern hardware architectures [2, 3]. Unstructured meshes and multi-rate time-stepping efficiently deal with multi-scale solutions [2, 6]. We adopted the MPI+X approach for distributed programming together with OCCA [5], a unified framework to make use of major multi-threading languages (e.g. OpenMP, OpenCL and CUDA), offering a flexible approach to handling the multi-threading X. The load balancing of our implementation reduces both device–host data movement and MPI node-to-node communication.

While RTM procedure generally requires massive data storage with slow I/O, the thin halo regions inherent in DGTD discretizations eliminate the need to frequently checkpoint volumetric field data. Low storage requirements for DGTD boundary data allows halo trace data to be stored in memory rather than relying on disk based check-pointing. Similarly MPI communications in the reverse time phase can be reduced by retaining outgoing boundary trace data from the forward time calculation and replaying them during the reverse time calculation.

In this talk, we present the main features of the schemes used in RiDG, as well as choices taken for an efficient, accelerated, parallel implementation. Numerical results are proposed to evaluate and illustrate the computational performance for forward simulations and reverse time migration calculations.

avatar for Amik St-Cyr

Amik St-Cyr

Senior researcher, Shell
Amik St-Cyr recently joined the Royal Dutch Shell company as a senior researcher in computation & modeling. Amik came to the industry from the NSF funded National Center for Atmospheric Research (NCAR). His work consisted in the discovery of novel numerical methods for geophysical... Read More →

Tim Warburton

Rice University
Over the last decade Tim has developed and analyzed discontinuous Galerkin methods for the time-domain Maxwell’s equations. He has recently extended this research agenda to include the development of high order, local artificial radiation boundary conditions to provide closure for... Read More →

Thursday March 5, 2015 11:25 - 11:45 CST
BioScience Research Collaborative 6500 Main Street, Houston, Tx 77005

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