Clogging mechanisms in geothermal operations: theoretical examples and an applied study

Fluid reinjection is one of the most widely used and effective technologies in geothermal operations. It is applied due to different reasons, such as aquifer recharge or produced water disposal. Despite various benefits of this technology, reinjection often also causes a decrease of the well injectivity due to clogging, as observed worldwide. Three main groups of clogging mechanisms can be identified: physical, chemical and biological processes. These processes act individually and interdependently both in reservoir pore spaces and in well and surface equipment. As a result of clogging, porous media as well as wellbore equipment can get obstructed, which typically leads to permeability reductions and associated declines in injectivity.
In this contribution, we provide a theoretical review of clogging mechanisms, along with different external parameters affecting each type of clogging. We support this discussion by a case-study of a geothermal field in the Netherlands. In this study, well and reservoir data are analyzed to identify the reasons for injectivity decline. These data are further compared to the theoretical correlations obtained from a literature overview to constrain the driving mechanisms of the process.