A High-Resolution Seismic Survey to Image the Top of Salt at Avery Island, Louisiana

Dawn Standridge¹, Cathy Bishop¹, Gary Kinsland², Robert Schneider², and Laura Serpa^2
1Department of Geology, University of Louisiana at Lafayette, Lafayette, Louisiana 70504
²Department of Geology and Geophysics, University of New Orleans, New Orleans, Louisiana 70148

A shallow high-resolution 2D seismic reflection survey was acquired to image the top of the salt dome at Avery Island, Louisiana. The goals were to identify the salt-sediment interface and to gain a better understanding of its location within the subsurface. Previous seismic studies were unable to properly image the top of salt. The survey was conducted using a 48-channel seismograph with an Elastic Wave Generator as the source. Source and receiver intervals were set at 10 ft (3m) in order to properly illuminate salt surface features at maximum expected depth (~530 ft). Because local well information was unavailable during processing and analysis, the survey results are not calibrated to a known geologic section or to any direct velocity measurements.

Analysis of the seismic stack shows five well-defined reflectors near the north end of the profile. Measured stacking velocities associated with deep events were observed to be greater than 2,000 m/s. This indicates possible pore space salt cementation in sediments above the salt body. To the south, the top of salt is interpreted to approach the surface with one area displaying evidence of a possible collapse feature.

The five reflectors expand northward from the edge of the top of salt, and show evidence of minor faulting. This is consistent with draping and post-sedimentation movement. Further studies to better identify the collapse feature and to calibrate seismic to stratigraphy by well coring is warranted.

AAPG Search and Discovery Article #90080©2005 GCAGS 55th Annual Convention, New Orleans, Louisiana