Chemicals used in hydraulic fracturing have raised concerns about their potential for water contamination, and many discussions have focused on the necessity of chemicals for hydraulic fracturing and maintaining well integrity.
While chemicals are fundamental to the hydraulic fracturing process, the fluids used for hydraulic fracturing in shale gas are almost entirely comprised of water and sand. Chemical additives are required to help ensure safe and effective performance and different geologic formations require different blends of ingredients. These chemicals, many of which are commonly found in household products, have various purposes. The functions include friction reduction, clay stabilization, temperature stabilization of the fluids, suspension and transport of sand, control of bacterial contamination, and corrosion inhibition.
Wells are constructed to ensure these chemicals remain safely contained within the wellbore system and specific steps are taken to manage the chemicals at the well site to prevent spills. In the wellbore, the likelihood of hydraulic fracturing fluids migrating from a gas reservoir to a water table is extremely low because the two zones are typically separated by thousands of feet of rock and there are impermeable natural barriers within this rock that preclude upward migration. In order to protect against accidental release, XTO employs responsible operational practices when designing, drilling, and maintaining the well to ensure that fluids and the produced gas are properly handled in the well and on the surface.
ExxonMobil has long supported the disclosure of ingredients used in hydraulic fracturing fluids on a well-by-well basis. We consulted with the Ground Water Protection Council and Interstate Oil and Gas Compact Commission as they developed the FracFocus online registry. We continue to work with industry associations, state governments, and the Bureau of Land Management on having the registry being accepted as the best approach to optimally and effectively focus on the appropriate disclosures.