Otton, James K.1, Robert A. Zielinski1, Bruce D. Smith1, Bobby D
(1) U.S. Geological Survey, Lakewood, CO
(2) U.S. Geological Survey, Lafayette, LA
ABSTRACT: Environmental Impacts of Oil Production on Soil, Bedrock, and Vegetation at the U. S. Geological Survey OSPER Study Site A, Osage County, Oklahoma
The lease at the Osage-Skiatook Petroleum Environmental Research (OSPER) site A in Osage County, Oklahoma, produced about 100,000 barrels of oil between 1913 and 1981. Prominent production features include a tank battery, an oil-filled trench, pipelines, storage pits for both produced water and hydrocarbon sludge, and an old power unit. Site activities and historic releases have left open areas in the local oak forest adjacent to these features and a deeply eroded salt scar downslope from the pits which extends to nearby Skiatook Lake. The site is underlain by surficial sediments comprised of very fine grained eolian sand and colluvium as much as 1.3 m thick which, in turn, overly flat-lying, fractured bedrock comprised of sandstone, clayey sandstone, mudstone, and shale. A geophysical survey of ground conductance and concentration measurements of aqueous extracts (1:1 by weight) of core samples taken in the salt scar indicate that unusual concentrations of Na-Cl-rich salt are present at depths to at least 8 m in the bedrock however, little salt occurs in the eolian sand. Historic aerial photographs, anecdotal reports from oil-lease operators, and tree-ring records indicate that the surrounding oak forest was largely established after 1935 and thus postdates the majority of surface damage at the site. Blackjack oaks adjacent to the salt scar have anomalously elevated chloride (>400 ppm) in their leaves and record the presence of NaCl-rich salt or salty water in the shallow subsurface. The geophysical measurements also indicate moderately elevated conductance beneath the oak forest adjoining the salt scar.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.