Data-acquisition for HT-ATES design combined with geothermal drilling

Demonstrating win-win symbiotic opportunities with the ULTIMATE and WarmingUP project

15 months in, the first data-acquisition drilling was performed to research the potential of the underground for subsurface heat storage, which started off the practical work for my PhD research. During the last weeks of January and the first weeks of February 2022, we acquired important data to identify suitable layers for seasonal subsurface heat storage with High-Temperature Aquifer Thermal Energy Storage (HT-ATES). This test drilling in Maasdijk was conducted in conjunction with a drilling for geothermal energy. Combining multiple drilling goals proved to be feasible and effective.

The data acquired with this drilling has two aims. Firstly, it will be used to determine if suitable aquifers for heat storage are available in the local subsurface, which is relevant for local greenhouses that may benefit from HT-ATES utilization. Secondly, it will serve as an essential input for my broader PhD research to assess characteristics of potential layers for HT-ATES application. In this light, we will carry out two more drillings in Feb-Mar-Apr 2022 with the WarmingUP project, one in Rotterdam and one in Delft.

Local subsurface properties essential for HT-ATES

Within the ULTIMATE project, several demonstration projects are developed to demonstrate innovative circular water, resources, and energy solutions. Within this work, the potential for the integration of HT-ATES in a district heating network for a horticultural region in the Westland area is being assessed.

Important aspects that determine the potential for HT-ATES are the local layering and the properties of the subsurface. Most importantly, an aquifer is needed with adequate permeability and thickness (often sandy layers) confined by low permeable layers (aquitards, often clayey). Hence, it is important to know whether such layers are available at a certain locations and what their properties are. We recently reported on the important properties of the subsurface, and appropriate methods to measure them, for application of HT-ATES, as part of our work for the WarmingUP project.

Successful ‘special’ drilling in Maasdijk

Early 2022, a drilling crew from Haitjema drilled to 275m depth in Maasdijk, targeting the Maassluis and Oosterhout formations. During this process, we took several core samples of sandy and clayey layers, which I subsequently transported to the TU Delft lab.

The drilling design here was special, because we didn’t drill a dedicated borehole, but deeper in an existing hole. In Maasdijk a geothermal energy project  consisting of 3 doublets is being installed. Early 2022 the top parts of the 6 geothermal wells were drilled, which are called conductors and are the starting point for the further geothermal well drilling towards ~2.9km depth. These conductors consist of a steel casing with a diameter of 800mm and depth of 140m. As 1) this is about the depth where interesting formations for HT-ATES start, 2) a drilling rig and drilling facilities are already available on location and 3) this saves us 140m of drilling, we figured that this might be an interesting and cost-effective opportunity for data acquisition for our project and for other potential HT-ATES users in the Westland area. In good collaboration with HVC and Haitjema we designed the deepening project and carried it out.

The drilling rigs of Haitjema in operation. In the front: conductor drilling, in the back: deepening project.

As seasonal heat storage is often a very interesting addition for geothermal energy projects, combining both these activities might be something that we can apply to more geothermal projects in the future!

More test drillings will provide PhD input

Since October 2020, my work at KWR changed a bit, as I also started with PhD research within the framework of the WarmingUP project. My research focuses on the performance and sustainable use of HT-ATES. The subsurface data that we acquire with the drilling described above is important input for the PhD research. The main objective here is to determine how subsurface properties impact HT-ATES systems’ performance and how these subsurface properties can be determined efficiently.

Three drillings, which are part of the WarmingUP project, are also important locations where we are able to collect samples for my PhD; test drillings in Rotterdam, Delft and Leeuwarden. Recently, the Algemeen Dagblad came to the drill site in Rotterdam and wrote a news article about the test drilling and why subsurface heat storage is of interest here.

With the information from all drillings we aim to find out which layers in the subsurface are suitable for HT-ATES. As the drillings provide valuable information of similar formations in the subsurface, but at different depths and locations, these results will be of value to assess the spatial variability of subsurface characteristics. For example, this will give us insights to assess the value of already available drilling information (e.g. from oil, gas, geothermal) for new HT-ATES locations.

During the first 1.5 years of my PhD a lot of time went into preparing these drillings, so it is very nice that we are now actually drilling and collecting data. Later in 2022 we start with (lab) analysis of all collected data, to be continued!

Some sandy layers with high shell content at about 215m depth, an indicator for the Formation of Maassluis.