TY  - JOUR
A1  - Tranter, Morgan Alan
A1  - De Lucia, Marco
A1  - Wolfgramm, Markus
A1  - Kühn, Michael
T1  - Barite scale formation and injectivity loss models for geothermal systems
JF  - Water
N2  - Barite scales in geothermal installations are a highly unwanted effect of circulating deep saline fluids. They build up in the reservoir if supersaturated fluids are re-injected, leading to irreversible loss of injectivity. A model is presented for calculating the total expected barite precipitation. To determine the related injectivity decline over time, the spatial precipitation distribution in the subsurface near the injection well is assessed by modelling barite growth kinetics in a radially diverging Darcy flow domain. Flow and reservoir properties as well as fluid chemistry are chosen to represent reservoirs subject to geothermal exploration located in the North German Basin (NGB) and the Upper Rhine Graben (URG) in Germany. Fluids encountered at similar depths are hotter in the URG, while they are more saline in the NGB. The associated scaling amount normalised to flow rate is similar for both regions. The predicted injectivity decline after 10 years, on the other hand, is far greater for the NGB (64%) compared to the URG (24%), due to the temperature- and salinity-dependent precipitation rate. The systems in the NGB are at higher risk. Finally, a lightweight score is developed for approximating the injectivity loss using the Damkohler number, flow rate and total barite scaling potential. This formula can be easily applied to geothermal installations without running complex reactive transport simulations.
KW  - reactive transport
KW  - radial flow
KW  - geothermal energy
KW  - scaling
KW  - phreeqc
KW  - formation damage
Y1  - 2020
U6  - https://doi.org/10.3390/w12113078
SN  - 2073-4441
VL  - 12
IS  - 11
PB  - MDPI
CY  - Basel
ER  -