Hydraulic Fracturing in Bowland Shale Lancashire, UK July. 2 nd,2013 ISC Quarterly Meeting

Slide 2 /14 Analyzing Data Correlating the fracking job and seismicity Improved microseismic imaging Developing a predictive model based on geophysical data Objectives

Slide 3 /14 Background Gemechanical Study of Bowland Shale Seismicity Academic Review Work Done Summary

Slide 4 /14 From: UK Onshore Geophysical Library NUMBERWELLSORTABLEDEVCOUNTYSPUDCOMPLETEDLatitudeLongitude LJ/06- 5LJ/ VLANCS16-Aug-1016-Apr maps.lynxinfo.co.uk/UKOGL_LIVEV2/main.html # Preese Hall 1 well (PH1) om/UK_Shale/ Bowland Shale Area of Low Seismicity ML=4.4 near Lancaster (1835) Cuadrilla: 200 trillion cubic feet of gas-in-place The first unconventional shale gas well in the UK Background

Slide 5 / non-felt events: -1.5<ML< March to 27 May 2011 Seismic Events

Slide 6 /14 Numerous wellbore failures: strike-slip faulting stress regime (σ Hmax > σ V > σ Hmin ) σ Hmax ≈1.25 psi/ft Craven Fault system Pendle Fault system (Cuadrilla, 2011) Thick Anhydrite Thistleton fault mapped by seismic The seismicity caused by a type A fault Thistleton Fault PH1 Carboniferous rocks overlain by Permian and Triassic strata Gemechanical study of Bowland Shale seismicity

Slide 7 /14 Stage 2 (Cuadrilla, 2011) 5 Fracking stages The strongest event: 10 hours after shut-in 6 Minifrac stages Treatments

Slide 8 /14 No certainty about the seismicity mechanism / Timing of the seismicity & Similar signals Strike-slip stress regime Events: present in stages 2&4 / absent in stages1,3, &5 Worst case vertical fluid migration: 2000 ft / Thick impermeable formation on top of the Bowland shale as well as the anhydrite layer Seismicity unlikely to happen in next wells o Proppant: hard for slurry to enter a fault o PH 1: fluid entrance into a fault => unlikely to occur again Conclusion of the study

Slide 9 /14 Plausible Cause o Direct fluid Injection into adjacent fault zone -Fault intersected the wellbore OR Fluid was able to flow into fault through bedding planes. o Critically stressed faults in the region Finding o Reduction in normal stress on fault causing it to fail repeatedly in a series of small events.(Strike –Slip Stress regime) o Reservoir is overpressurized and fluid leakoff is unusually high Academic review (Green, et. al,2012)

Slide 10 /14 B-value map shows insufficient no. of recorded events for convergence. B-value Prediction Work Done

Slide 11 /14 Trend b/w ∆BHP and Seismic Events Stage II Work Done

Slide 12 /14 Co-relation between Q i,BHP and magnitude of events. -Injection Data for stage IV and Stage V. Prediction of Time lag b/w ∆BHP and seismic events. -Accurate data for all stages. Future Work and Limitations Work Done

Slide 13 /14 British Geologic Survey Commodities Now, ‘Fracking 'probable' cause of Lancashire quakes,’ Nov., 2011 Davies,R, et. al.,’ Shale Gas: The Rocks Matter,’ Cuadrilla Resources,’Geomechanical study of the Bowland Shale seismicity,’ 2011 Green, C.,A., et. al.,‘Preese Hall Shale Gas Fracturing Review & Recommendations for Induced Seismic Mitigation,’2012 References

Thank You!