Suggested best practice for seismic monitoring and characterization of non-conventional reservoirs
Marco Bohnhoff, Peter Malin, Jan ter Heege, Jean-Pierre Delflandre and Charles Sicking
Journal name: First Break
Issue: Vol 36, No 2, February 2018 pp. 59 - 64
Special topic: Reservoir Monitoring
Info: Article, PDF ( 2.33Mb )
General awareness of induced seismicity and gas leakage related to energy reservoir exploitation has been on the rise for several years (McGarr, 2002; Davies et al., 2013). This includes events from short-term fluid injection for reservoir simulation (Giardini, 2009; Atkinson, 2016), Long term hydrocarbon extraction (Van Thienen-Visser and Breuness, 2015), under¬ground storage of natural gas (Cesca et al., 2014), waster water (Ellsworth, 2013), and carbon dioxide (Zoback and Gorelick, 2012). High rates of felt induced events in previously quiet areas are now considered critical for public safety and social licence to operate (Petersen et al, 2016). Concerns about con¬tamination of ground water and climate effects have followed suit (Darrah et al., 2014; Davies et al., 2014). Prominent injection-induced seismicity that raised concerns are: the Preese Hall-1 frack-related M2.3 in the United King¬dom (de Pater and Baisch, 2011; Clark et al., 2014); an M~3.4 during the Basel, Switzerland, Geothermal project (Häring et al., 2008; Giardini, 2009), increased central-US water-disposal M>3 earthquakes (e.g. Ellsworth, 2013), and M~4 fracking-in¬duced events in Canada (Atkinson et al., 2016). In the case of gas leakage owing to loss of well integrity, industry long-run estimates range between a few per cent to as much as 50% (Burfatto et al., 2003). For non-conventional resource wells drilled since 2009 in Pennsylvania, well-inspec¬tion records suggest that as many as 40% have integrity issues (Davies et al. 2014; Ingraffea et al., 2014) and China (Lei et al., 2017). The proliferation of microearthquakes many times foreshad¬ows damaging ones and changes in well integrity. Substantial progress has been made in cost-effective, specialized seismic networks that can address these issues (e.g., Van der Baan et al., 2013). We describe these over a ~ 5 x 5 km reservoir in a ~10 x 10 km lease. As the optimal best practice, we suggest the monitoring scheme be integrated into a reservoir-management plan using Seismic Emission Tomography (SET; e.g. Sicking et al., 2017). In addition to adding value for fracture characterization and production management, only a portion of a permanent SET net is needed for regulatory compliance.