Environmental Risk Assessment and Management Methodologies in Oil Production Frameworks

The most common sources of hydrocarbon emissions in the oil and gas industry are as follows (Picard, 2000): - Fugitive equipment leaks; - Process venting; - Evaporation losses (e.g. tanks and wastewater treatment); - Venting or flaring of disposal waste gas streams; and - Accidents or equipment failures. Fugitive equipment leaks originate from valve stem packings, unions, pipe thread fittings, and hatches (Alberta Research Council, Inc., 2004). Well blowouts, pipeline breaks, tanker accidents, tank explosions, gas migration to the surface around the outside of wells, and surface-casing vent blows are also sources of hydrocarbon emissions, including methane, a potent greenhouse gas ("GHG") (Picard, 2000). Studies conducted during 2007 by the Texas Commission on Environmental Quality ("TCEQ") using Differential Absorption Light Detection and Ranging ("DIAL") indicate that poorly-performing flares may also be large sources of hydrocarbon emissions in petroleum refineries (Clawson, 2007). Emissions from fugitive sources have traditionally been estimated using emission factors, such as those found in the U.S. EPA’s compilation of emission factors known as AP-42. Studies performed in Europe and North America over the past decade reveal that hydrocarbon emissions from refinery and natural gas processing operations may be 10 to 20 times greater than the amount estimated using emission factors (EPA, 2006). In addition to the environmental implications, hydrocarbon losses represent opportunities for significant financial savings. Some companies have reported savings of over $1 million per year by locating and adjusting a single major fugitive leak (Cuclis, 2008). For a large refinery reporting non-methane, non-ethane hydrocarbon emissions of 2,500 tons per year, assuming an economic value of $0.40 per pound of hydrocarbon, the reported emissions represent a loss of US$2 million annually (Cuclis, 2008). If actual losses are 10 to 20 times higher than reported, then the economic value of the lost material increases to between US$20 and $40 million for this same refinery. Unidentified or underestimated emissions may also pose safety risks to workers and to the public. In the presented posters different methodological approaches to evaluation and modeling of hydrocarbon emissions from refinery and natural gas processing operations are described. Particularly the attention will be stressed about the most up to date technical and methodological tools for both the emissions detection, with Optical Remote Sensing technologies, and the emission modeling, with Comprehensive Air quality Model with extensions CAMx. Both tools offer the opportunity to significantly improve our understanding of both the sources and magnitudes of hydrocarbon emissions.