The objective of the project is to obtain a better understanding of the mechanisms and phenomena occurring during (re)injection of cooled formation water in argillaceous sandstone low-enthalpy geothermal reservoirs and to find adequate solutions for the problem of too low or reduced injectivity.
The project has resulted in the first ever, fully integrated approach for understanding permeability, including new laboratory methods for assessing permeability reduction, modelling of permeability decline, and in-situ percolating tests. In addition, the project proved that in-situ test injections were a costly and ineffective method.
The project consists of two major subprojects :
1. Research leading to the improvement of the injectivity index of argillaceous sandstone formations during exploitation of low enthalpy geothermal energy.
2. Study of the influence of argillaceous particles on the conditions for reinjection of cooled geothermal fluid into the Miocene sandstone reservoirs of the Madrid Basin.
Although, in the past, decline of injectivity due to formation damage has been observed during exploitation of geothermal energy from argillaceous sandstone reservoirs in several demonstration sites, until now an international approach in research could not be executed due to financial and logistical constraints. This project will approach the injectivity problem in a systematic way applying different techniques and experiences in four European countries.
Expected project results are:
1. Identification and understanding of the physical and (geo)chemical laws and mechanisms controlling the changes in injectivity, based on formation evaluation including petrography, percolation tests on cores, formation water analyses and petrophysics. The relevant parameters will also be monitored during injection in an operating geothermal doublet. 2. Improvement of the predictability of formation injectivity, both short and long term, through study and adaption of numerical modelling techniques to be combined with formation evaluation data.
3. Improvement of knowledge regarding design specifications for optimal well completion, water treatment and safe injection rates with the purpose of being able to minimize formation damage or to restore and/or increase the injectivity of an existing or planned low enthalpy geothermal injection well, leading to improved efficiency and economics.
Funding SchemeCSC - Cost-sharing contracts
2600 GA Delft