XEGCat of Tarragona (2021-2023)

Stations and instrumentation

The XEGCat Tarragona will have 14 newly built monitoring points (boreholes) and between 6 and 10 pre-existing water points that will be periodically monitored. The network, similar to the first XEGCat network implemented in the urban and peri-urban area of Girona Salt and Vilablareix, will be divided into two sub-networks:

• Primary subnet: 14 measurement stations will be built corresponding to 14 boreholes of about 100 meters in depth. Of these, 4 will be completed as closed loop heat exchangers and 10 boreholes will be completed as open piezometers. All of them will be equipped with temperature sensors according to different configurations and piezometric level sensors. In the 4 points finalized as closed points, thermal response tests (TRT) are planned to be carried out during the second half of 2023.
• Fiber optics installation in the primary subnet: Each borehole will be equipped with hybrid fiber optic cable along its entire length. This installation will allow in situ measurements of temperature at different depths and also the performance of thermal response tests (TRT) with the application of heat through the hybrid fiber optic cable.
• Secondary subnet: It will be made up of between 6 and 10 monitoring points corresponding to piezometers and pre-existing wells in the area. These will be monitored by installing an autonomously operating temperature and piezometric level sensor. Additionally, temperature profiles will be carried out periodically at points where possible. The secondary subnetwork is expected to be operational during the last quarter of 2023.

 

Location map of the 14 projected new construction points of the XEGCat of Tarragona (Primary subnetwork)

In relation to the geothermal stations of the primary subnet, these may be open or closed depending on the completion of the borehole carried out.

The stations corresponding to open boreholes will be equipped with a 114 mm diameter PVC piezometric tube (114/104 mm). Inside the piezometric tube, a piezometric level (water column pressure) and temperature sensors will be installed. In addition, hybrid fiber optic cable will also be installed to carry out temperature measurements along the entire length of the survey.

The stations corresponding to closed loop heat exchangers will be equipped with a PE100 40.0 x 3.7 mm simple U geothermal probe and will subsequently be cemented with thermoactivated cement slurry, with a density between 1.1 and a maximum of 1.35 gr / cm3 and a minimum thermal conductivity of 2 W/(m·K). In these stations, temperature sensors will also be installed at different depths and a hybrid fiber optic cable that will allow thermal response tests or TRT (Thermal Response Test) to obtain thermal conductivity and resistivity data from the drilling. The result reports of these trials will be downloadable in PDF format.

In a similar way to the XEGCat implemented in the urban and peri-urban area of Girona, all stations in the primary network will also be equipped with a telemetry system for the automatic acquisition and transmission of data. The data will first be stored in a temporary data recorder to be automatically sent to the spatial database of the NetMon© system (Monitoring System for Measurement and Control Stations) of the ICGC.

 

Drilling works with core recovery from the Imperial Tarraco geothermal station (SXGT14), recovery core box and hybrid cable coil of optical fiber and copper cable. Construction scheme of the open geothermal stations with piezometers of the primary network. Non-recoverable core drilling works. Outside of one of the monitoring stations still without data collection, power and transmission devices.