If a well has a drawdown of 27 feet and a theoretical drawdown of 18 feet, what is the well efficiency?

To determine the efficiency of the well, the concept of well efficiency is calculated by comparing the theoretical drawdown to the actual drawdown. The formula for well efficiency is given by:

Efficiency = (Theoretical Drawdown / Actual Drawdown) × 100%

In this case, the theoretical drawdown is 18 feet, and the actual drawdown (the drawdown measured in the well) is 27 feet. By substituting these values into the formula, we calculate:

Efficiency = (18 feet / 27 feet) × 100% = 66.67%

When rounded, this results in an efficiency of approximately 67%. Therefore, the well’s performance, as indicated by this calculation, reflects that it is operating at two-thirds of its theoretical efficiency. This shows how closely the well performs compared to the expected performance under ideal conditions, highlighting areas where efficiency could be improved.