Estimating Sustainable Yield to a Well in Heterogenous Strata

In Alberta, aquifers are heterogeneous, so current methods of predicting sustainable yields are inappropriate. Even the common term transmissivity is not applicable and should be replaced by the new term transmissive capacity, which takes into account the dependence on time of the average conductive capability of the volume drained by a well during production.

Estimators based on a sample of short-term transmissive capacities can be used to predict the expected value of long-term transmissive capacity at the producing well. Once estimates of long-term transmissive capacity are available, both 20-year safe yield and the drawdown at the well resulting from any production program can be calculated. The method suggested for estimating long-term transmissive capacity is empirical, so it must be validated by successful application to suitable field cases. This method was applied to two field cases in Alberta, but further validation is required. However, the method presented for calculating safe yield depends only on the value of the long-term transmissive capacity, not on how the value was determined, so it can be used whenever that information is available.