Geoelectrical Imagining of Hydrocarbon Plumes: Two Louisiana Case Studies

Scott Sallay¹, Carl Richter¹, and Bill Schramm²
¹ University of Louisiana, Lafayette, Louisiana 70504
² Louisiana Department of Environmental Quality, Baton Rouge, Louisiana 70821

We present results from geoelectrical resistivity surveys that were conducted to investigate the extent of soil contamination and to image the dimensions of two hydrocarbon (gasoline) plumes in locations near Port Barre and Felixville, Louisiana. Pipeline leaks at both locations released gasoline and dissolved phase hydrocarbons into the subsurface. These contaminants can be detected with geoelectrical methods because they exhibit extremely high resistivity values compared to surrounding sediments and soils. A significant amount of geochemical data has already been collected at the Port Barre site and are used to ground truth and calibrate the geoelectrical resistivities. The intent of the Felixville study is to investigate the extent of the contamination plume, to detect the origin of the pipeline leak with geoelectrical imagery, and to assist in future remediation design efforts. Resistivity data were collected at both sites using the Geometrics OhmMapper, which is a tool for quickly measuring resistivity values in the shallow subsurface. We produced 2D vertical sections (Felixville) and 3D volumes (Port Barre) using data inversion to determine the shape and extend of the plumes. Based on the interpretation of these models, the contaminants at the Port Barre release site are floating on top of the water table and moving in the ground water flow direction. The 2D sections at the Felixville Station site clearly identify the extent of the hydrocarbon plume and the origin of the leaks.

AAPG Search and Discovery Article #90158©2012 GCAGS and GC-SEPM 6nd Annual Convention, Austin, Texas, 21-24 October 2012