Accelerating seismic computations using customized number representations on FPGAs |

Seismic imaging is the most computationally demanding technology of the oil and gas sector. Downward continued based migration (Gazdag and Sguazzero, 1985) is the most prevalent high-end imaging technique today, and reverse time migration appears to be one of the dominant imaging techniques for the future.

Downward continued migration comes in various flavors including Common Azimuth Migration (Biondi and Palacharla, 1996), shot profile migration, source-receiver migration, planewave or delayed shot migration, and narrow azimuth migrations. The different techniques have varying cost profiles but all share two meaningful computational bottlenecks: transforming to-and-from the wavenumber domain (FFT) and applying the single square root (SSR) or double square root (DSR) condition (complex exponentials).

The cost of explicit space-domain 3-D reverse time migration is dominated by the cost of continuing the source and receiver wavefield a given time step. To progress the wavefield a given time step requires applying a 3-D stencil that can range in size from 7 to 31 points depending on the finite-difference approximation that is chosen.

In this paper, we describe the implementation of DSR equation and the kernel of 3-D acoustic modeling on a FPGA. We begin by giving a basic background of FPGAs. We describe the FPGA programming environment and our methodology for determining the correct trade off between precision and speed. We then describe the implementation procedure for both algorithms. We conclude by discussing potential additional speedup opportunities of both reverse time and wavefield continuation based migration.

Accelerating seismic computations using customized number representations on FPGAs |

2007-09-18