Seismicity and Rock Mechanics towards Harnessing of Geothermal Energy
Seismicity
It is well known that increased levels of seismicity are expected with the production of geothermal energy, and there are several aspects that need to be taken into consideration here. First of all, there is safety. This includes the safety of people directly involved in the operation but also the safety of the local community. Secondly, environment. Good care of the environment during operations needs to be taken, considering all of the risks and doing everything possible to minimise them. Monitoring of seismicity can provide an early warning in case of any operations problems. Thirdly, the infrastructure. Monitoring of seismicity can also help with the mitigation of hazards directly affecting the infrastructure of the site (well integrity, casing, boreholes, etc).
Finally, the knowledge. It is extremely important to gather as much information and data as possible during operations. This can be used later by scientists for deeper understanding of the physical processes, performing detailed analyses towards the reduction of potential failures in future operations.
In all of these fields, monitoring seismicity provides quantitative measurements that, when used appropriately, can help mitigate against hazards associated with induced seismicity.
The video above features Piotr Salek from the Institute of Geophysics Polish Academy of Sciences speaking about mitigating the risks and seismic / environmental impact associated with geothermal applications.
Rock Mechanics and Mineral Analysis
Understanding the physical changes in reservoir conditions is a challenging task due to the small amount of information available from the conditions at 2, 3 or 5 kms depth inside the earth. Rock mechanics is a field of research that allows us to understand how fractures behave at those pressure conditions that occur in natural reservoirs. This field of research combines theoretical, experimental and modelling techniques to explain the role of the stress fields in fluid flow and mineralisation in the Earth’s crust, making it crucial to the overall operation. Meanwhile, mineral analysis and geochemistry are tools that allow us to dig into the chemical changes that transform, dissolve or precipitate minerals at depth. The consequences of these changes can deeply affect the efficiency of the whole reservoir. For this reason, it is important to look at the geothermal system as a whole and combine physical-chemical perspectives when exploring, assessing and developing a geothermal field. Catalina Sanchez-Roa from University College London spoke to TWI about rock mechanics and the geological challenges associated with geothermal energy exploitation.