Technical risks and best available technology (BAT) of hydraulic fracturing in unconventional natural gas resources

Description of risks associated with (a) the technical installations above ground at the well site, (b) the transport of environmentally hazardous substances on roads and in pipelines, and (c) the technical design of the wellbore that can arise during specified normal operation and any deviations therefrom (accident). The assessment is based on a worst-case scenario approach that allows for definition of the measures necessary to avoid accidents and limit their consequences, in accordance with the state-of-the-art requirements [Best available technology (BAT)]. The measures, thus, defined were then compared with given technical and organizational preventive measures for a typical installation, and the completeness and suitability of these measures were evaluated. The investigation is based on information and documentation that were provided by ExxonMobil Production Deutschland GmbH on selected drilling sites, as well as on the literature. Simulations were run for eight main scenarios and 28 subsidiary scenarios. The state-of-the-art (BAT) and good management practice were defined for measures aimed at preventing drilling site incidents and limiting their effects, and were then compared with and assessed in light of standard practices. The said comparison then formed the basis for the formulation of recommendations aimed at improving protection of the population and environment. The main recommendation is that hydrofracking operations should be conducted in accordance with prevailing chemical industry standards, even if adherence to these requirements is not prescribed by law. This especially pertains to requirements concerning the following: the manner in which substances that are hazardous to water are handled; pipeline requirements for natural gas, backflow water and formation water transport; and instituting modern cultures of safety, including providing information concerning risks and the elaboration of risk management action plans. Recommendations were also made as regards well integrity testing, in view of the mission critical nature of this matter and the need for integrated risk communication.