Buried Bedrock Channels in the Athabasca Oil Sands Region Conceptual Understanding and Implications to Water Supply

Transcription

1 Buried Bedrock Channels in the Athabasca Oil Sands Region Conceptual Understanding and Implications to Water Supply Scott Rayner Matrix Solutions Inc. Sandra Rosenthal Devon Canada Corporation

2 Presentation Outline Study area Regional and local geology Hydrogeology hydraulic head mapping groundwater chemistry Implications to water supply Summary/Conclusions

3 Fort McMurray Study Area and Surface Topography St o ny M ou nt ai n Up la nd s Athabasca River Clearwater River Ma yh ills Mostoos Hills Uplands

4 Regional and Local Geology

5 Hydrostratigraphy Top of Bedrock CHANNEL SAND AQUIFER

6 Bedrock Topography (Andriashek, 2003) Fort McMurray Gregoire Channel Clearwater River Channel width can range from less than 500 m to greater than 30 km Channel length can range from less than 10 km to greater than 200 km Can incise into Cretaceous bedrock greater than 150 m Athabasca River Christina Channel Kirby Channel Wiau Channel Andriashek, L.D Quaternary Geological Setting of the Athabasca Oil Sands (In Situ) Area, Northeast Alberta EUB/AGS Earth Sciences Report

7 Local Bedrock Topography Christina Channel Kirby Channel Sunday Creek Channel

8 South to North Structural Cross Section A-A A A Wiau Channel Sunday Creek Channel Christina Channel La Biche Joli Fou Joli Fou Channel Sand Aquifer Grand Rapids C McMurray

9 Subcropping Cretaceous Formations An Integrated Interpretation Christina Channel Kirby Channel 3D Seismic Area Sunday Creek Channel 2D Seismic Line

10 Sunday Creek Channel Cross Section A 930 m A AA/ W4 AB/ W4 AA/ W4 900 m Sunday Creek Channel La Biche Sunday Creek Channel Viking Joli Fou Grand Rapids A Grand Rapids B 150 m Viking Joli Fou Grand Rapids A Grand Rapids B Grand Rapids C Channel Sand Aquifer Grand Rapids C Clearwater Shale 350 mbgs Clearwater Shale Clearwater A

11 Hydrogeology

12 South-North Regional Schematic Hydrostratigraphic Cross Section Aquifer Aquifer/Aquitard Aquitard Local Study Area Undifferentiated Overburden Channel Sand Aquifer La Biche Aquitard La Biche Aquitard Joli Fou Aquitard Upper Grand Rapids Aquifer Lower Grand Rapids Aquifer Clearwater B AquiferClearwater A Aquifer Undifferentiated McMurray Basal McMurray Aquifer Beaverhill Lake Group

13 Channel Sand Aquifer Extent Fort McMurray Clearwater River Athabasca River Leismer Channel Gregoire Channel Christina Channel Wiau Channel Kirby Channel Sunday Creek Channel

14 Groundwater Flow Fort McMurray Clearwater River Channel Sand Aquifer Athabasca River Christina Channel Wiau Channel Sunday Creek Channel CHANNEL SAND AQUIFER

15 Athabasca River Groundwater Flow Grand Rapids Formation Fort McMurray Clearwater River Stony Mountain Uplands

16 West to East Structural Cross Section With Interpreted Hydraulic Head Contours Kirby Channel Sunday Creek Channel La Biche Joli Fou Channel Sand Aquifer La Biche Joli Fou Channel Sand Aquifer La Biche Joli Fou Grand Rapids C McMurray

17 Total Dissolved Solids Concentration versus Depth Increase in TDS with depth from less than 1,000 mg/l to greater than 18,000 mg/l Non-Saline Saline

18 Change in Groundwater Chemistry with Depth (Surface Water) Change in water type from calcium-bicarbonate to sodium-chloride

19 Lower Grand Rapids Aquifer Average Resistivity (R t ) and TDS Distribution Christina Channel Kirby Channel Sunday Creek Channel

20 Implications to Water Supply

21 Implications to Water Supply Source well deliverability is increased as a result of the groundwater mounding (higher available head) in the Grand Rapids Source wells have been located away from the deepest channel incisions to ensure saline groundwater is withdrawn In accordance with the Alberta Environment Water Conservation and Allocation Guideline for Oilfield Injection Sodium chloride water (TDS 4,000 to 10,000 mg/l) is easier to treat (for steam generation) As operations continue, pressure and groundwater chemistry will be monitored

22 Lower Grand Rapids Aquifer Isopach Incision into Lower Grand Rapids Aquifer Observation Wells Source Wells Up to 44 m thick

23 Summary/Conclusions An integrated approach is required when solving water supply challenges The depth of incision and subcropping Cretaceous formations strongly influences: hydraulic head distribution within the channels and Cretaceous formations groundwater chemistry of Cretaceous formations The presence of buried bedrock channels have important implications to water supply in terms of deliverability and source water chemistry