ASSESSMENT AND REMEDIATION OF A HEAVY OIL SPILL INTO GROUNDWATER AQUIFERS

Abstract

ABSTRACT The Cold Lake Production Project is located in northern Alberta, Canada. The project currently produces approximately 15,000 cubic meters of heavy oil per day. Production involves the injection of steam at very high pressure and temperature into the reservoir to reduce the viscosity of the heavy oil (the steam phase). The oil is then pumped to the surface through the same well bore in which the steam is delivered (the production phase). The process is termed “cyclic steam stimulation.” During the winter of 1995 a series of six well casings under steam failed and released approximately 55,000 cubic meters of material to the environment. The material was a mixture of oil, saline produced water, and solids, including shale, glacial till, sand, and clay. The failures occurred at various depths from 95 to 250 meters below ground and traveled upward to the surface. The spill affected two local groundwater aquifers. This paper describes the Cold Lake heavy oil production process, and then the chronology of events that resulted in the T-pad casing failure incident. Impact assessment methods, including surface geophysics, piezometer well installation, groundwater quality data collection, and contaminant fate and effects modeling, are presented, as well as remediation techniques. Much was learned from the T-pad incident regarding oil contamination within the groundwater aquifer systems.