| Title | Drilling Challenges and Solutions for HT-ATES Systems in Deep Aquifers |
|---|---|
| Authors | Alexis Koulidis, Martin van der Schans, Martin Bloemendal, Philip J. Vardon |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | |
| Abstract | Underground thermal energy storage can play a vital role in supporting the energy transition by enabling more efficient use of sustainable resources. Among the various technologies, High-Temperature Aquifer Thermal Energy Storage (HT-ATES) is a promising solution for seasonal thermal energy storage. HT-ATES systems are mostly proposed in shallow aquifers, taking advantage of cost effective drilling and high permeabilities and low operational costs. However, large temperature contrasts can also occur. To ensure economic viability and long-term wellbore integrity of those systems, the drilling process and well completion play a critical role. The long-term performance of these systems is a function of the drilling process and drilling fluid design, well completion, as well as well development and rehabilitation. Drilling fluid must ensure borehole stability and be easily removable during well development to avoid a reduction in hydraulic conductivity. Additionally, well completion and annular materials should withstand heating and cooling cycles, provide long-term zonal isolation, and be corrosion resistant, especially in saline aquifers. Well screen and gravel pack design should ensure reliable sand control while maximising flow efficiency. This paper presents field case studies and experimental investigations that offer insights and provide practical considerations for the well design and implementation of HT-ATES systems in deep, unconsolidated formations. We address the specific challenges associated with drilling, well completion, and well development for high-temperature, low-pressure conditions. The findings contribute to a better understanding of creating an optimum well design, maintaining aquifer hydraulic conductivity, and ensuring the long-term integrity and efficiency of HT-ATES operations. |