Hydraulic Fracturing

Hydraulic fracturing is a topic of much political and public debate, and the messages about concerns and practices are often conflicting. In this talk, we will discuss the hydraulic fracturing process and some of the monitoring techniques currently used in light of some of these concerns.

Transcript

1. Image source: http://pacwestcp.com/wp-content/uploads/2013/02/PacWest_NAM-Key-Plays_Feb-2013.jpg
2. National Energy Board, 2015 https://www.neb-one.gc.ca/nrg/ntgrtd/mrkt/dnmc/2014/2014nrgdnmc-eng.pdf
3. First Hydraulic Fracturing Experiment - 1947 (Montgomery and Smith, 2010)
4. First Hydraulic Fracturing Experiment - 1947 US EIA 2012 : http://www.eia.gov/forecasts/aeo/pdf/0383(2012).pdf
5. http://www.thebakken.com/uploads/posts/web/2013/09/ECOPadSite_13789287916813.JPG http://energyindepth.org/marcellus/karen-moreau-discusses-natural-gas-and-hydraulic-fracturing/ Well Pads
6. First Hydraulic Fracturing Experiment - 1947 US EIA 2012 : http://www.eia.gov/forecasts/aeo/pdf/0383(2012).pdf
7. Section of well isolated Fluid pumped until rock fractures Proppant pumped to keep fractures open Fracturing Process
8. • Drill past aquifer: Freshwater or air for drilling fluid • Surface Casing Drilling the well: Near Surface https://www.youtube.com/watch?v=VY34PQUiwOQ Steel Casing Cement Drill Bit Open Hole
9. • Surface Casing Drilling the well: Near Surface https://www.youtube.com/watch?v=VY34PQUiwOQ Steel Casing Cement http://fracfocus.ca/groundwater-protection/drilling-and-production
10. Drilling the well: in the reservoir • Drilling continued, horizontal in reservoir layer • Drilling mud circulated to keep drill bit cool and remove cuttings • Cased with steel and cement (or a sleeve) https://www.youtube.com/watch?v=VY34PQUiwOQ Vertical “leg” ~2-3km, Horizontal “leg” ~1-2km,
11. • Perforate the well (hydraulic connection between well and reservoir) Drilling completions “perf gun” perforations ~cm https://www.youtube.com/watch?v=VY34PQUiwOQ
12. • Water pumped into well until : hydraulic pressure > minimum stress + tensile strength of rock Fracturing https://www.youtube.com/watch?v=VY34PQUiwOQ
13. Fracturing: Proppant
14. Fracturing maximum horizontal stress minimum horizontal stress
15. Surface pressure Flow Rate Proppant Concentration a b c d e f g h a b c d e f g h minimum horizontal stress maximum horizontal stress Fracturing
16. Surface pressure Flow Rate Proppant Concentration a b c d e f g h a b c d e f g h minimum horizontal stress maximum horizontal stress Fracturing
17. Fracturing
18. • ~ 20 - 50 stages completed along horizontal leg of well Fracturing packers stages https://www.youtube.com/watch?v=VY34PQUiwOQ http://www.geoexpro.com/articles/2012/05/from-trickle-to-gusher-the-bakken-oil-story
19. Figure 3 (ch2): Maxwell, 2014
21. Materials Proppant ~ 5% • Sand or Ceramic Particles Fluid ~95% • Water ~99% • Chemicals, typically < 1% Chemical Disclosure Registry (http://fracfocus.ca) Acid helps dissolve minerals and initiate cracks Corrosion Inhibitor prevent corrosion of the pipe Biocide eliminate bacteria in the water Surfactant friction reducer Gelling Agent thickens the water in order to suspend the sand Commonly used additives (http://fracfocus.ca)
22. (where did it go?)
23. Microseismic Tiltmeters Pressure Tracers, Logs Far Well • microseismic (fibre optics) • tiltmeters • pressure Near Well • well logs • tracers • temperature (fibre optics) Monitoring Techniques
24. Monitoring Techniques Microseismic
25. Concerns • (Hydrocarbons in general, obviously) • Shallow aquifer contamination • Induced seismicity
26. • (Hydrocarbons in general, obviously) • Shallow aquifer contamination • Induced seismicity Concerns • 3 potential sources: ◦ from surface ◦ from well ◦ from fractures
27. Fracture Height Growth (Maxwell, 2011) http://csegrecorder.com/articles/view/hydraulic-fracture-height-growth • most aquifers within the first few hundred meters of the surface • unlikely to “frack into” the aquifer • however, connections to pre-existing faults can provide a slow pathway for diffusion of gas into aquifer
28. Concerns: Shallow aquifer contamination surface storage casing http://fracfocus.ca/groundwater-protection/drilling-and-production References: Methane in aquifers - no frac fluids found in aquifers • Osborn et al, 2011 • King, 2012 Drilling?, Natural seeps?
29. Concerns • Does fracking cause earthquakes? • induced vs triggered? • (Hydrocarbons in general, obviously) • Shallow aquifer contamination • Induced seismicity
30. Induced Seismicity Ellsworth, 2012: http://science.sciencemag.org/content/341/6142/1225942.full
31. Induced Seismicity National Research Council, 2013
32. Induced Seismicity Ellsworth, 2012: http://science.sciencemag.org/content/341/6142/1225942.full BC Oil and Gas Commission Report, 2015
33. Induced Seismicity Traffic Light system Ellsworth, 2012: http://science.sciencemag.org/content/341/6142/1225942.full King, 2012
34. Resources Overview of Fracturing Practices and Risks: • King (2012) ◦ Hydraulic Fracturing 101: What Every Representative, Environmentalist, Regulator, Reporter, Investor, University Researcher, Neighbor and Engineer Should Know About Estimating Frac Risk and Improving Frac Performance in Unconventional Gas and Oil Wells • Chemical Disclosure Registry (http://fracfocus.ca) • BC Oil and Gas Commission (http://www.bcogc.ca) • National Research Council, 2013: Induced Seismicity Potential in Energy Technologies • Canadian Induced Seismicity Collaboration (http://www.inducedseismicity.ca)
35. my research where do the injected fluid and proppant go?
36. Microseismic Tiltmeters Pressure Tracers, Logs Far Well • microseismic (fibre optics) • tiltmeters • pressure Near Well • well logs • tracers • temperature (fibre optics) Monitoring Techniques
37. Microseismic Tiltmeters Pressure Tracers, Logs Far Well • microseismic (fibre optics) • tiltmeters • pressure Near Well • well logs • tracers • temperature (fibre optics) Monitoring Techniques Limited sensitivity to the proppant or fluid distribution at the scale of the reservoir...
38. Imaging the Proppant and Fluid 3 things we need: 1. Physical property contrast 2. Survey Sensitive to the Contrast 3. Means of interpreting the data
39. Electromagnetics? 3 things we need: Maxwell’s equations Constitutive Relations 1. Physical property contrast 2. Survey Sensitive to the Contrast 3. Means of interpreting the data Electrical Conductivity EM survey Time lapse inversion
40. Tools.
41. Physical Property Model for fractures? • mm thick • 100’s m long • complex geometry Steel Cased Wells? • highly conductive, • permeable, • long, • thin, • cylindrical, • and horizontal wells... Hydraulic Fracturing: challenge of scales
42. Modelling the Fractured Reservoir
43. Steel Cased Wells? • highly conductive, • permeable, • long, • thin, • cylindrical, • and horizontal wells... Hydraulic Fracturing: challenge of scales
44. Modelling the casing: Source types magnetic flux density current density current density current density
45. Impact of Magnetic Permeability magnetic flux density
46. Simulating 3D Geology + Casing Casing in simple background 3D structures (no longer symmetric…)
48. Thank You! Thanks to Mark Novakovic at UWO for educating me on induced seismicity! Questions? contact: lheagy@eos.ubc.ca