Overview of Environmental Investigations and Remediations of Leaks and Spills in Oil and Gas Fields

JACOBS, JAMES A., Artesian Environmental Consultants, Mill Valley, CA, R. TRAVER, Chapman, Inc., Freehold, NJ, and O. T. JACOBS, Artesian Environmental Consultants, Mill Valley, CA

Historic and current leaks and spills in oil and gas fields can involve a variety of hazardous compounds, can be located virtually anywhere on-site, and may significantly degrade soils and groundwater quality. Leaks and spills of crude oil can occur around wells, pipelines, pumping equipment, above-ground storage tanks, and barrels; refined petroleum fuels can leak or spill from above and below ground storage tanks, barrels, pumping units, and pipelines. Drilling muds, including such historically documented additives such as chrome, lignosulfonate, and asbestos fibers can leak or spill from mud pits, wells, sumps, impoundments, and barrels. In addition, the following hazardous compounds are typically found in equipment maintenance and chemical storage areas in oil and gas fields: hydr ulic fluids, painting wastes, used equipment lubrication oils, unused free fluids and acids, radioactive-tracer wastes, waste solvents, biocides, and pesticides. PCBs, a dielectric fluid, are common to transformers built prior to 1979.

Environmental evaluation of historic and current leaks and spills in oil and gas fields occurs in the investigative stage, characterized by a site assessment and field evaluation. The site assessment includes a site survey, aerial photo interpretation, review of regulatory agency records, operators' records, previous work by consultants, and interviews with knowledgeable persons. The field evaluation, designed to examine the lateral and vertical extent of the spill or leak, could include a soil gas survey, cone penetrometer, trenching, and drilling. Using these techniques, collected soil or groundwater samples can be analyzed in a laboratory to differentiate the various hazardous compounds on-site.

Once an environmental investigation has been performed to define the vertical and lateral extent of a spill and the potential pathways that the hazardous compound will move to expose a given population, then remediation options can be designed. Remedial programs for hazardous compounds commonly found in oil and gas fields include the following in-situ technologies: volatilization, biodegradation, leaching and chemical reaction, vitrification, passive remediation, and isolation/containment. Non-in-situ technologies include land farming, incineration, asphalt incorporation, solidification/stabilization, groundwater extraction and treatment, chemical extraction, and excavation and offsite disposal. Factors affecting remedial measures are cost of technology, time available to finish remed ation, technical feasibility, regulatory acceptance, and accessibility and availability of space in the remediation area.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)