This grid represents the distribution of total dissolved solids (TDS) in the Exshaw–Banff hydrostratigraphic unit (HSU). It is a result of a geostatistical model which was constructed using publicly available data from formation water chemistry data from drillstem tests (DST) and production fluids from oil and gas wells.
The distribution of TDS was mapped at a regional scale using many years of data, thus providing a good indication of regional water chemistry within the unit rather than site-specific values.
The following statistics describes the accuracy of the geostatistical layer used to create the final grid:
Mean error = -237 mg/L
Root mean square error = 11878 mg/L
Mean standardized error = -0.01325745
Root mean square standardized = 1.003377
Average standard error = 11582.1 mg/L
The root mean square error of the final smoothed grid is 7 413 mg/L.
See AGS DIG 2023-0025 (data points) for details on the horizontal accuracy of the input TDS point data, which is affected by the locational accuracy of the wells.
The grid was smoothed using focal statistics which calculates for each input cell location a statistic of the values within a specified neighbourhood around it, in this case a 5-cell by 5-cell rectangle. Smoothing the surface used the average cell value.
Description: Selection criteria and the final dataset used for interpolation of this grid are documented in the metadata for AGS DIG 2023-0025.
Step 1 (Modelling the surface): An empirical Bayesian kriging algorithm was used in the ArcMap 10.8.1 Geostatistical Analyst extension to interpolate the TDS values and create a grid of the TDS in the Exshaw–Banff HSU.
Method Report:
Output surface type: Prediction
Transformation: None
Neighborhood type: Standard circular
Maximum neighbours: 15
Minimum neighbours: 10
Sector type: 4 sectors with 45° offset
Samples: 396
Cell Size: 500 m by 500 m
Step 2 (Grid Smoothing): The grid was smoothed using focal statistics which calculates for each input cell location a statistic of the values within a specified neighbourhood around it, in this case using a 5-cell by 5-cell rectangle, smoothing the surface using the average cell value.
Step 3 (Grid Alterations): The final grid was clipped based on the extent of the Exshaw–Banff HSU, and spatial distribution of data.