During a well capacity test, the standard initial measurement interval and subsequent interval?

• A. Every 1 minute then every 10 minutes
• B. Every 5 minutes then hourly
• C. Every 2 minutes then every 20 minutes
• D. Every 10 minutes then hourly

Answer: (A)

The main idea is to capture the rapid initial response with high time resolution and then switch to a longer interval as the drawdown slows. Measuring every minute at the start records the immediate wellbore and aquifer reaction, including any short-term storage effects, so you don’t miss important early behavior. After that first phase, switching to every 10 minutes provides enough data points to define the slower late-time drawdown without creating unnecessary data volume. The other options either miss the initial rapid changes or wait too long to sample the continuing decline, which can lead to an inadequate understanding of the well’s capacity and the aquifer response.