Monthly Lecture

Angela Pascarella & Lies Peters (TNO) will talk about:

Contribution of borehole image for the understanding of heterogeneous geomechanical properties and cooling in a sandstone geothermal reservoir.

Abstract
Understanding the impact of long-term injection on geothermal reservoir properties is critical for sustainable energy production. Within the Dutch national innovation program Geo4all, we investigated geomechanical heterogeneities and thermal cooling in a siliciclastic geothermal reservoir located in the Middenmeer Geothermie license area, operated by Ennatuurlijk Aardwarmte. In 2025 a replacement production well (MDM-GT-11-S2) was drilled adjacent to an injector well that was active for a decade; several well log data, including a borehole image, were acquired in the replacement well with the intent of comparing predicted cooling models with measured temperature profiles and to assess reservoir properties before and after prolonged injection.

Measured temperatures were compared to modelled temperatures, conventional petrophysical logs were analyzed to derive porosity, permeability and elastic moduli, fractures (interpretation by SLB) and facies were interpreted on the image log and calibrated to cores from the same reservoirs in a different well.

The results of such analyses show that thermal cooling was concentrated within approximately one-third of the reservoir thickness. Well log analysis revealed significant variability in elastic moduli and reservoir properties and image log analysis revealed variability of sedimentological facies and fracture type and density along the borehole. The integration of these analyses has allowed to establish the existence of a link between cooling patterns, facies and fracture distributions, identifying facies more affected by cooling and facies where cooling inducing fractures seem more likely to develop.

Unlocking low temperature geothermal reservoirs: Key insights for exploitation of geothermal energy from medium depths (500-1500 m)

Abstract
Low Temperature Geothermal (LTG) energy in the depth range of 500 to 1500 m is potentially a valuable source to support the heat transition in The Netherlands. However, due to a lack of operational knowledge, experience and subsurface uncertainty, developing such projects currently carries considerable risk. In this work, information related to drilling, completions and operations has been brought together from current developments in this depth domain. These are mainly oil and gas fields and one geothermal doublet. The results show that with respect to drilling, considerable knowledge and experience is available, which show how to drill the required well designs with sufficient step-out at shallow depth. For completions, and in particular operations, much less experience is available. Different completions have been used in the poorly or unconsolidated formations in this depth domain, but these need to be tested for the rates, fluids and subsurface characteristics that can be expected for LTG. On the production side, increasing flow rates from conservative oil & gas baselines, will improve the business case of LTG, but problems due to fines migration or sand production need to be understood and included in the planning to prepare for long-term economic operation.

Program:
17:30-18:00 hrs: Social hour
18:00-19:00 hrs: Lecture
19:00-20:00 hrs: Social hour

Teams meeting link: Link to be shared in the PGK newsletter.

Venue:
Oudaen, Oudegracht 99, Utrecht