On-Site Bioremediation Systems Reduce Crude Oil Contamination
- W.W. Hildebrandt (Groundwater Technology Inc.) | S.B. Wilson (Groundwater Technology Inc.)
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- January 1991
- Document Type
- Journal Paper
- 18 - 22
- 1991. Society of Petroleum Engineers
- 2.2.2 Perforating, 2.4.3 Sand/Solids Control, 4.1.2 Separation and Treating, 4.1.4 Gas Processing, 7.2.1 Risk, Uncertainty and Risk Assessment, 4.3.4 Scale, 5.8.5 Oil Sand, Oil Shale, Bitumen, 4.1.9 Tanks and storage systems, 2.4.5 Gravel pack design & evaluation, 6.5.3 Waste Management, 4.2 Pipelines, Flowlines and Risers, 6.5.5 Oil and Chemical Spills, 1.11 Drilling Fluids and Materials
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Oilfield properties frequently have areas where soils contain concentrations of crude oil. These soils can be either "hazardous wastes" or "designated wastes" under regulatory guidelines. As a result, property owners and financial institutions face potential liabilities when oilfield potential liabilities when oilfield properties are transferred to new properties are transferred to new operators, abandoned, or converted to other uses.
Modern, well-designed soil bioremediation systems are cost-effective ways to treat soils that contain concentrations of crude oil, and these systems can eliminate an owner's subsequent liabilities. A modern on-site bioremediation system requires significantly less surface area, results in lower operating costs, and provides more effective, expeditious provides more effective, expeditious results than traditional land-farming practices. It also eliminates potential practices. It also eliminates potential long-term liabilities and is typically more cost-effective than excavation and off-site disposal of oilfield soils.
Case studies indicate that on-site bioremediation systems have reduced crude oil contamination in soil to levels acceptable to regulatory agencies in less than 20 weeks (in some cases, less than 10 weeks). Total costs for on-site bioremediation range from $35 to $120/yd of treated soil, including excavation, depending on specific site requirements.
During normal operation of oilfield properties, crude oil or other materials frequently properties, crude oil or other materials frequently leak or spill onto land surfaces. These degraded soils are commonly associated with oil wells, sumps and pits, tank batteries, gathering lines, and pump stations. Crude oil and drilling muds may also he found in these areas and, like the contaminated soil, they may be considered either hazardous wastes or designated wastes under current regulatory guidelines. The regulations pertaining to crude oil vary across the U.S. In California, for example, crude oil is considered a designated waste and its off-site disposal is subject to regulations. If certain constituents (e.g., benzene) are present in sufficiently high concentrations, the present in sufficiently high concentrations, the soil degraded by crude oil may he considered a hazardous waste and subject to additional regulations. Crude oil sludge in an old sump typically contains oilfield treatment chemicals; therefore, the sludge is considered a hazardous waste.
Regulations usually specify the levels to which contaminated soils and groundwater must he cleaned up. Occasionally, however, a quantitative human-health-risk assessment may he used to determine the significance of the presence of crude oil on oilfield properies. An environmental-risk assessment properies. An environmental-risk assessment can show the potential health effects from the measured on-site concentrations and give levels acceptable to regulators.
When oilfield properties are transferred to new operators, abandoned, or convened to other uses, the presence of degraded oil can significantly reduce the value of the property or even lead to cancellation of the property or even lead to cancellation of the transaction. Lending institutions are concerned also because of their potential liabilities if the borrower defaults. Hence, current property owners frequently consider property owners frequently consider remediation or removal of the contaminated soils.
If soils are to be reworked to reduce the concentrations of hydrocarbons or other contaminants, regulatory agencies often must he notified. These agencies may require the installation of groundwater monitoring wells and may establish long-term reporting and monitoring requirements. Excavation and off-site disposal of the degraded soil is often considered but can he quite expensive. In addition, potential liabilities generally remain with the oilfield operator if the degraded soil is transported to a landfill or another site. Soil bioremediation, on the other hand, eliminates an owner's subsequent liabilities and can he very cost-effective, particularly when performed on site.
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