Characterization of the shale gas production: A case study in a sector of the Lusitanian Basin

Abstract

This study aims to characterize the shale gas exploration in Portugal through the impacts generated by its extraction technique – the Hydraulic fracturing – on the environmental, social and economic sector. The extraction of shale gas has been a controversial issue mainly due to its influence on oil prices and the negative environmental impacts involved in the exploitation process – in particular, the contaminated water that returns to the surface after the drilling process, i.e. the flowback water. To support this analysis, it was performed three different analyses: 1) a chemical analysis of a flowback water sample from the Marcellus formation, US; 2) delimitation of the study area in Lusitanian Basin based on its geological characteristics; 3) an investment sensitivity analysis applying the method of net present value (NPV). The chemical analysis revealed flowback water values within the expected parameters, confirming its high toxicity. Then, based on the analysis of surveys carried out in the Lusitanian Basin, the study area was delimited from Benfeito, Torres Vedras 4 to Sobral. Finally, the sensitivity analysis finds that, comparing with the base case scenario, the variation of Capital expenditure is the parameter that most influences the profits and payback period. To conclude, shale gas exploitation in Portugal would lead to high economic benefits, despite the existence of a relatively more inefficient fee system that fails to truthfully reflect its negative environmental impacts.