Field Permeability Tests: Importance of Calibration and Synchronous Monitoring for Barometric Pressure Sensors

Abstract

Pressure transducers (PTs) and an atmospheric pressure transducer (APT) were used to register test data during two types of permeability tests, which were performed in 14 wells monitoring a confined aquifer installed in the lab, and a field rising-head test in clay. The constant-head tests were performed using a peristaltic pump and thus functioned as constant flow rate tests until stabilization of the water level in the well riser pipe. The rising-head tests were started by the sudden removal of a slug of water. This article presents, first, the method used to calibrate the transducers to assess their systematic calibration error (offset) values. Then, it quantifies the influence of synchronized monitoring for the (PT-APT) pair on short- and long-term test data, which had never been done before. The results indicate that the pair calibration cannot be neglected and that the synchronized monitoring is important for all tests, except maybe for a short-duration variable-head test. For most tests, however, the barometric fluctuation with time plays a significant role.