3D ELECTRICAL RESISTIVITY TOMOGRAPHY SURVEY OF HISTORIC WELLS IN OSAGE COUNTY, OKLAHOMA

Abstract

The Tallgrass Prairie Preserve (TGPP) is the largest protected area of tall grass prairie, spanning a 12,146 Ha area in Osage County, Oklahoma. Oil production has been prevalent since the 1870s. A significant portion of the production in the area consists of salt water (brine). Brine is a primary contaminant of concern because brine spills on the surface result in the destruction of plants and erosion of top soil. It can also enter the subsurface via faulty well casings and contaminate the groundwater. Two, un-catalogued wells (‘Well 1’ and ‘Well 2’) were identified in the southern portion of the TGPP that are potentially discharging brine to surrounding groundwater. Previous studies have shown that surface water within the catchments of the wells contained elevated concentrations of brine contaminants. The present study aims to measure the distribution of electrical resistivity in the shallow subsurface around the wells in order to determine if the wells are a source of contamination. Additionally, the electrical conductivity of soils and streambed sediments will be measured in areas adjacent to the wells. Electrical resistivity and conductivity surveys can be applied to the brine contamination studies because contaminants associated with brine cause affected waters to be highly conductive to electrical current. Results from this study will help us determine if the brine has migrated laterally away from the wells and discharge into the surface water system.

AAPG Datapages/Search and Discovery Article #90221 © 2015 Mid-Continent Section, Tulsa, Oklahoma, October 4-6, 2015