eprintid: 1909 rev_number: 9 eprint_status: archive userid: 6 dir: disk0/00/00/19/09 datestamp: 2017-05-16 11:39:44 lastmod: 2017-05-16 11:39:44 status_changed: 2017-05-16 11:39:44 type: article metadata_visibility: show creators_name: Schwartz, Michael O. corp_creators: MathGeol, Germany title: Modelling the hypothetical methane-leakage in a shale-gas project and the impact on groundwater quality subjects: O subjects: RG subjects: SHU divisions: SHEER full_text_status: none keywords: Groundwater protection, Hydrochemical modelling, Fracking, Natural gas abstract: The hypothetical leakage of methane gas caused by fracking a 1,000-m deep Cretaceous claystone horizon at Damme, Germany, is simulated in a TOUGHREACT reactive-transport model with 5,728 elements. A hypothetical leakage zone connects the Cretaceous horizon with a Quaternary potable-water aquifer (q1). Methane gas rises up to the q1 horizon in less than 2 days in all calculated scenarios. The simulations include the major constituents of groundwater as well as the seven most hazardous trace components that are natural constituents of groundwater (As, Cd, Cr, Ni, Pb, Se and U). The general trend is characterised by depletion of the natural hazardous components with decreasing acidity and oxygen fugacity in the relevant pH range (7–9). Nevertheless, the concentrations of elements whose dominant aqueous species are negatively charged in this pH range (Cr and Se) rise against the general trend due to desorption reactions. Slight enhancement effects are produced by the dissolution of contaminant-bearing oxides such as Cr-bearing goethite. In summary, the geological risks of a fracking operation are minor. The technical risks are more important. This is especially the case when rising methane gas gets into contact with fracking fluid that accidentally escapes through faulty well seals. date: 2015-04 date_type: published publication: Environmental Earth Sciences volume: 73 number: 8 publisher: Springer Verlag pagerange: 4619-4632 id_number: DOI 10.1007/s12665-014-3787-3 issn: 1866-6280 access_IS-EPOS: limited owner: Publisher citation: Schwartz, Michael O. (2015) Modelling the hypothetical methane-leakage in a shale-gas project and the impact on groundwater quality. Environmental Earth Sciences, 73 (8). pp. 4619-4632. DOI: https://doi.org/10.1007/s12665-014-3787-3