Prof. Dietrich Borchardt, Helmholtz-Zentrum für Umweltforschung, UFZ
Based on a set of thematic studies the “Independent Expert Group” carried out a detailed investigation on the effects of the Fracking-Technology for the extraction of natural gas on people and the environment as well as into possible measures to limit these effects.
The generic study examines possible risks in the areas under exploration – and therefore assumes conditions of the kind that prevail in the areas under exploration in North Rhine-Westphalia and Lower Saxony.
In view of the multitude of geological situations and types of reservoirs, the study describes seven typical geological situations (settings) in the exploration regions that reflect the different conditions encountered there.
The study defines worst case scenarios in order to describe the maximum technological risks at the well site, in the well and during transport (tankers, pipelines) in the event of conceivable accidents.
The following list describes the principle assumptions for worst cases in comparison to regular operations.
| Worst-Case | Regular Case | |
|---|---|---|
| Integrity of drilling | Shearing, cementation is not tightly | Integrity of drilling is ensured |
| Drilling site | Release of materials by fire / explosion / accident | no fire / explosion, tanker accidents or demolition of hose |
| Pipeline | Spills or uncontrolled releases | Leak-proof pipeline |
| Transport | Tanker accident with complete release of substances | Transport without release of substances |
| Frack propagation | Fracks enter the fields with deep groundwater (Münsterland) | Fracks remain in target horizon |
| Fault zones | Encountering more permeable, continuous fault zones | No permeable, continuous fault zones |
| Pressure gradient | Pressure gradient due to the presence of artesian groundwater | Low pressure gradient (Münsterland: pressure gradient exists) |
| Pressure gradient through interaction with other production wells / or older wells in the nearer environment | no interaction with other production wells / old wells in the nearer environment | |
| Methane mobilisation | 20% of the mobilized supply of methane migrate to the top | ??? |
| Matter transport | Conservative matter transport | Mixing processes, adsorption and, degradation processes |
| Assessment of toxicity | Assessment based on the most sensitive indicator | No contact of the most sensitive organism with contaminants |
The Expert Group has decided to apply a deterministic risk assessment. This implicitly means, it has to be confirmed that worst-case scenarios are controllable. The deterministic approach, however, incorporates two probability statements that need to be addressed. First, it must be clarified, which worst-case scenarios may occur, and what absolutely improbable events would be. Second, statements are required to the question how safe the methods for limiting and controlling of impacts are.
The results clearly show: risks and environmental degradation are linked with the Fracking Technology, and these should be taken seriously. In particular, the (technical) risks during transportation, storage, and in the well can contaminate groundwater. In contrast, pollutants may rise from deep geological layers only in certain unfavorable situations. About the rise of methane only very limited knowledge is available: burning of taps is known without Fracking but whether and to what extent this phenomenon amplifies is unknown. In the near future less quantities of Fracking fluids and less environmentally hazardous compositions of substances will be applied- and thus the relative hazard of the backflow water becomes more important. It has to be noted, that many of these risks exist even with a natural gas production from conventional reservoirs.
In addition to a possible contamination of groundwater, there are other relevant aspects. Depending on the diffuse methane emissions, the carbon footprint may be worse than natural gas from conventional reservoirs. Furthermore, uncoordinated development of drilling sites may result in landscapes of a disordered development and industrial sprawl. The transport of waste water and flow back and the immersion into disposal wells poses risks. Finally, the regional economic effects of the Fracking Technology are considered.
Based on the peer-reviewed scientific work, the Group of Experts will draw recommendations in a further step as to whether – and, if so, under what conditions – hydraulic fracking and the extraction of natural gas from unconventional reservoirs are compatible with the protection of people and the environment.
