This grid represents the distribution of total dissolved solids (TDS) in the Swan Hills / Slave Point hydrostratigraphic unit (HSU). It is a result of a geostatistical model which was constructed using publicly available formation water chemistry data from drillstem test and production fluids from oil and gas wells.
The TDS surface was mapped at a regional scale using many years of data, thus providing a good indication of the regional water chemistry distribution 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 = 117 mg/L
Root mean square error = 16 168 mg/L
Mean standardized error= 0.004
Root mean square standardized= 0.967
Average standard error= 16 224 mg/L
The root mean square error of the final smoothed grid is 11 563 mg/L.
See AGS DIG 2022-0008 (data points) for details on the horizontal accuracy of the input TDS 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 2-cell radius. Smoothing the surface used the average cell value.
Selection criteria and the final data set used for interpolation of this grid are documented in the metadata for AGS DIG 2022-0008
Step 1 (Modelling the surface): An empirical Bayesian kriging algorithm was used in the ArcMap Geostatistical Analyst extension to interpolate the TDS values and create a grid of the TDS surface of Swan Hills / Slave Point HSU.
Method Report:
Method: Kriging
Type: Empirical Bayesian kriging
Output type: Prediction
Transformation: None
Subset size: 100
Searching neighbourhood: Standard Circular
Maximum neighbours: 15
Minimum neighbours: 10
Sector type: 4 sectors
Samples: 402
Cell size: 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 a 2-cell radius. Smoothing the surface used the average cell value.
Step 3 (Grid Alterations): The final grid was clipped based on the extent of the Swan Hills / Slave Point HSU, and spatial distribution of data.