Hydraulic fracturing is an established oil and gas well stimulation technique that has been in play in various forms for over sixty years and is critical to today’s United States (U.S.) production of most oil and gas resources (Montgomery, C., Smith, M. Hydraulic Fracturing: History Of An Enduring Technology. SPE JPT 2010, 62, 12, 26-32). As with any industrial activity, there are risks, both immediate and latent that must be considered. Concerns have been raised recently of ground water contamination, air pollution and other problems that may occur either as routine production activities or as a result of fracturing. These issues are complicated since oil and gas, with a myriad of co-generated hydrocarbon molecules from alkanes to ring compounds of benzene, toluene and xylenes, are simultaneously produced by naturally occurring thermal and pressure driven maturation reaction of some forms of organic carbons laid down with the sediments.
Sources of many of these hydrocarbons include the organic-rich shales that were deposited throughout many geologic time periods and in most parts of the world (Toutelot, H. Black Shale – its Deposition and Diagenesis. Clays and Clay Minerals, 1979, 27, 5, 313-321). As oil and gas is produced, some moves out of the shales and may be trapped in rock containments called reservoirs, but when these reservoirs are filled or when they are absent, the hydrocarbons rise via buoyancy towards the surface forming weathered or bacterial altered deposits near surface, or co-occupying space with subterranean water reservoirs, both brine and fresh.
Many concerns of potential pollution from hydraulic fracturing are actually concerns of materials transport, well construction, hydrocarbon production or distribution. This chapter will examine the direct impact of hydraulic fracturing as a primary target and the associated activities of hydrocarbon development as a secondary effort, using both historical performance and scientifically sound research methods.