Assessing the potential of cross-contamination from oil and gas hydraulic fracturing: A case study in northeastern British Columbia, Canada.

This paper presents the various tools and data sources in British Columbia (Canada) that can be used by environmental consultants to assess the potential of cross-contamination between shale gas formation fluids and shallow aquifers from hydraulic fracturing and related oil and gas activities. A systematic approach for evaluating the potential of cross-contamination using these data sources is applied to a specific case study at an undisclosed location in the northeastern part of the province. This approach includes defining and then evaluating the basic criteria for assessing the potential of cross-contamination. These criteria are: a leak source; a driving force such as buoyancy or head differential and a leakage pathway. This study has revealed that there is a potential of cross-contamination due to hydraulic fracturing activities and wellbore integrity issues. Wellbore integrity can be compromised by induced seismic events or by unintentional communication with offset hydraulic fractured wells. Induced seismicity is linked to the activity of hydraulic fracturing as well as to the deep disposal of wastewater.