Abandoned Oil and Gas Wells near Fort Knox, Kentucky

Abandoned and unrecorded wells may act as conduits for the contamination of ground-water supplies by oil and gas field brines and other pollutants. The casings of abandoned wells eventually develop leaks, which, if not properly plugged, can allow pollutants to reach freshwater aquifers that supply drinking water. Such is the situation in the Fort Knox well field near West Point, Kentucky. Abandoned oil and gas wells provide a route for deep formation brines to migrate upward into the shallow alluvial deposits and contaminate the water table aquifer. Many of the drinking water supply wells for Fort Knox have chloride concentrations in excess of maximum contaminant levels of 250 mg/l with some as high as 800 mg/l. Results from a previous ground-water sampling program confirmed that abandoned oil and gas wells are most likely the source of brine contamination in the Fort Knox well field.

Locating and assessing the condition of the abandoned wells in the vicinity of the Fort Knox well field is an important step toward reducing ground-water contamination. Once located and inspected, the wells can then be properly sealed to prevent the transmission of contaminants into and between aquifers. Unfortunately, older well locations are frequently unrecorded or inaccurately mapped. Records of locations for wells on file at the USGS Kentucky Water Science Center and the Louisville Gas and Electric Company were reviewed as part of an earlier investigation to describe the hydrogeology of the Fort Knox well field (Unthank and Nelson, 1999). The possible locations for thirty-two abandoned oil and gas wells were identified but only nine wells were verified in the field. Consequently, a more thorough and comprehensive abandoned oil and gas well inventory and integrity survey is needed to reduce and eliminate the brine contamination threat.

The specific objectives of this investigation are:

• Identify and locate in the field as many abandoned oil and gas wells as possible.
• For each found well, assess the condition of the casing and visually inspect open-hole segments of the well boring.
• Determine if the well is providing a route for the migration of brine into the alluvial deposits.

Related Publications

Hydrogeology and simulation of ground-water flow in the Ohio River alluvial aquifer near West Point, Kentucky [WRI 99-4265]

Assessment of ground-water contamination in the Alluvial aquifer near West Point, Kentucky [WRI 88-4166]

Partners

U.S. Army Corp of Engineers

U.S. Armory Center, Fort Knox, Kentucky

Additional information about the Abandoned Oil and Gas Wells at Fort Knox and the USGS project can be obtained from Mike Unthank, KY WSC, (phone) 502-493-1932, (email) munthank@usgs.gov.

Fort Knox wells water-level contours [December 2008].