Abstract: Assessment of Ground-Water Quality Impacts Caused by Land Spreading of Saline Oil and Gas Exploration and Production Solid Wastes

BARTON, ANDREW C., and E. SCOTT BAIR

A two-phase study was designed to evaluate ground-water quality changes resulting from land spreading of oil and gas field cuttings at a site in central Ohio. During the first phase, approximately 20 cubic yards of non-solidified saturated cuttings was spread over a 1500 square foot area adjacent to 11 monitoring wells used to obtain ground-water samples for analysis of major ions and trace metals. An EM-131 Earth Conductivity Unit also was used to track subsurface movement of any leachate. A brine plume delineated by elevated chloride concentrations and elevated specific conductivity values developed downgradient of the applied cuttings and moved quickly off the site following periods of rainfall.

The second phase of the study involved land spreading of saturated cuttings mixed with a solidifying agent. Column experiments were performed using the cuttings both alone and mixed with several industry-approved solidifying agents to determine the effectiveness of each agent in minimizing the leaching of major ions and trace metals. Based on these tests, Portland cement is likely to be mixed with saturated cuttings and applied to the field site for the second phase.

The results of this study are expected to provide the oil/gas industry with a viable and environmentally acceptable alternative to solidification and burial of wastes in brine pits. In spreading the brines in such a way, available surface area is increased, allowing for greater dilution and absorption resulting in reduced contamination in the subsurface.

AAPG Search and Discovery Article #90939©1997 AAPG Eastern Section and TSOP, Lexington, Kentucky