4D electrical resistivity monitoring of cyclic aquifer thermal energy storage

Abstract

The worldwide society needs more than ever to invest in new environmental friendly technologies to ensure the three E’s (Environmental protection, Environmental growth and Energy security). To tackle this problem, a technology as the Aquifer Thermal Energy Storage (ATES) might be employed. Beside the design phase, ATES systems need to be monitored to ensure the efficiency of the ongoing thermal process. Therefore, in the present Master Thesis the 4D Electrical Resistivity Tomography (ERT) is studied to assess its monitoring ability in ATES systems. In order to achieve this aim, a cyclic heat storage experiment has been performed and monitored by an ERT grid of 6 parallel profiles 60 m long, spaced each other by 3 m. The cyclic experiment was conducted in a site located in Hermalle-sous-Argenteau, in Belgium. It consisted in alternating 4 phases (one per day) of injections and withdrawals. During these phases, the water was injected (at 40°C) or pumped for 5 h with a flow rate of 3 m3/h. The obtained 2D time-lapse inverted models have been also converted in temperature values to better appreciate the thermal variations. Globally, the interpretation of both resistivity and temperature 2D time-lapse models led to successfully monitor the plume across the time and the space. Such results have been also compared with direct measurements made in 5 piezometers in the vicinity of the well, obtaining good agreement. Although 3D time-lapse inversions did not show perfect results, they contributed partially to monitor the plume. Finally, asymmetric results from 3D and 2D time-lapse models contributed to spot heterogeneities in the studied site. To conclude, this elaborated has demonstrated the potentials of the 4D ERT as monitoring tool in ATES systems, broadening the future perspectives of this topic.