2011ppt dev hydrologydecisionsupporttool_final

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Presentation by Allan Chapman on Development of a Hydrology Decision Support Tool on April 6, 2011 at the Unconventional Gas Technical Forum in Victoria, British Columbia

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2011ppt dev hydrologydecisionsupporttool_final

  1. 1. Unconventional Gas Technical Forum<br />Development of a Hydrology Decision Support Tool<br />Allan Chapman, PGeo, BC Oil and Gas Commission<br />April 6, 2011<br />
  2. 2. The Water Cycle in Shale Gas Operations<br />2<br />
  3. 3. Water Use in Shale Gas Development<br />3<br />Water Use – seismic, drilling, road freezing, washing, fraccing, others<br />Hydraulic fracturing (fraccing)<br />Volumes required (broad range):<br />Montney play – 10,000 to 30,000 m3/well<br />Horn River Basin – 25,000 to 70,000 m3/well<br />Trends<br />Horizontal laterals are longer<br />Number of frac stages is increasing<br />Total water usage is rising<br />Horn River Basin well pad<br />
  4. 4. Key Water Sources<br />4<br />Currently, the largest source of water for fraccing<br /><ul><li>Freshwater
  5. 5. Lakes, streams, rivers
  6. 6. Dugouts</li></ul>Surface<br />Water<br /><ul><li>Unconfined or confined aquifers
  7. 7. Variable water quality, but often fresh
  8. 8. More common in Montney than Horn</li></ul>Shallow Groundwater <br />(0-250m)<br /><ul><li>Disconnected from surface water
  9. 9. Often saline
  10. 10. Not common, except EnCana’s Debolt project</li></ul>Deep Groundwater (>1000m)<br /><ul><li>Saline
  11. 11. Variable quality
  12. 12. Can require treatment</li></ul>Flowback Fluid<br />
  13. 13. Water Use Approvals<br />5<br /><ul><li>In 2009/10, OGC approved ~300 water use permits
  14. 14. Section 8 of Water Act – short-term use of water
  15. 15. ~900 points of withdrawal on lakes and streams
  16. 16. Total volume approved ≈ 79,000,000 m3
  17. 17. Actual use estimated to be <5% of approved
  18. 18. Careful and considered management is VITAL</li></li></ul><li>Hydrology Modeling for Decision Support<br />6<br /><ul><li>With unconventional gas, water use has changed.
  19. 19. We need to understand the water resource.
  20. 20. Many questions to address:
  21. 21. What is the water supply in rivers and lakes?
  22. 22. How does it vary across seasons?
  23. 23. What are thresholds to maintain instream flows?
  24. 24. How much is available for industry, and when?
  25. 25. Need to use hydrology models:
  26. 26. Built on defensible hydrologic science and data
  27. 27. Models can evolve as information is enhanced in future
  28. 28. They are quantitative, rather than qualitative</li></li></ul><li>OGC Water Balance Model Development<br />7<br /><ul><li>Most hydrology models operate at daily or hourly time steps, and are data and computation intensive
  29. 29. Monthly time step models can be simpler
  30. 30. OGC approach based on Continuity Equation: </li></ul> Q = P – Et ∆S<br />where: <br /> Q = runoff<br /> P = Precipitation<br /> Et = Evapotranspiration<br /> S = Storage<br /> at a monthly time step<br /> Objectives:<br /><ul><li>Model monthly and annual runoff
  31. 31. Derived from existing gridded climate and hydrology data
  32. 32. Model at sub-basin scale
  33. 33. Encompass all of NEBC (Horn, Liard, Cordova, Montney) </li></li></ul><li>Data (Gridded)<br />8<br /><ul><li>Precipitation (P):
  34. 34. Climate BC (derived from PRISM – from U of Oregon)
  35. 35. 1961-1990 Normal (30-year average)
  36. 36. Gridded to ~1 km2 resolution
  37. 37. Evapotranspiration (Et):
  38. 38. cgiar (Consultative Group for International Agriculture Research)
  39. 39. Based on 30-year average
  40. 40. Gridded to ~1 km2 resolution
  41. 41. Land cover – MoF Vegetation Resource Inventory):
  42. 42. To distinguish wetland (muskeg, bogs, fens) from upland areas.
  43. 43. Used to adjust Et values</li></li></ul><li>Annual Precipitation<br />9<br />
  44. 44. 10<br />Annual Evapotranspiration (adjusted)<br />
  45. 45. Vegetation Characteristics for Et Adjustment<br />11<br />Et adjustments from:<br /><ul><li>Ministry of Forests’ vegetation inventory
  46. 46. Et measurements from literature (e.g. BOREAS)</li></ul>Location<br />
  47. 47. Annual Runoff - Water Availability<br />12<br />
  48. 48. Results – Annual Runoff – Model vs. Observations<br />13<br />Max<br />75th percentile<br />Average Runoff<br />Modeled Runoff<br />25th percentile<br />Min<br />Toad (upper) Trout Toad Grayling Raspberry BougieAdsett Prophet <br />
  49. 49. Results – Monthly Runoff - Horn River Basin<br />14<br />
  50. 50. Results – Monthly Runoff – Liard Basin<br />15<br />
  51. 51. “Test” Watersheds – for Modeled Runoff <br />16<br />
  52. 52. Modeled Runoff for “Test” Basins<br />17<br />2% of annual runoff<br />@ 50,000 m3/well<br />≈ 197 wells/year<br />
  53. 53. Annual Surface Runoff in Horn Basin ??<br />18<br /><ul><li>Annual runoff in HRB ≈ 1.7 x 109 (billion) m3
  54. 54. If 1% was used for gas well fraccing ≈ 17 x 106 (million) m3
  55. 55. Would support ≈ 350 gas well completions per year</li></li></ul><li>Next Steps<br />19<br /><ul><li>Refine model calibration for HRB, Liard and Cordova
  56. 56. Incorporate Montney Play into model
  57. 57. “Workshop” approach with MOE, and with UBC, UVic and UNBC hydrology modeling groups
  58. 58. “Workshop” concepts such as annual and seasonal thresholds with MOE, First Nations, industry, others
  59. 59. Build operational decision support tool (end of 2011)
  60. 60. Put model, tool, data, etc., into public domain</li></li></ul><li>Questions?<br />Allan Chapman, PGeo<br />Hydrologist<br />BC Oil and Gas Commission<br />Allan.Chapman@gov.bc.ca<br />

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