Injection related issues of a doublet system in a sandstone aquifer - A generalized concept to understand and avoid problem sources in geothermal systems

This study proposes a concept and presents workflow to examine potential reasons for low injectivity of sandstone aquifers. Injection related problems are major challenge the sustainable utilization geothermal waters. In order completely understand avoid reinjection problems, problem sources acting on different scales should be taken into consideration. Thus, in workflow, possible considered regional, reservoir local scale categorized 1) effect regional hydraulics (potential presence overpressure upward flow) 2) inadequate performance (limited extent, permeability performance) 3) clogging processes (particle migration, mineral precipitation, microbial activity). Hydraulic conditions characterized by defining pressure regime direction vertical driving forces. The properties given determining grain size layers, as well transmissivity capacity injector. Physical, chemical, biological investigated specifying rock particle content fluid; analysing type, probability amount scaling estimating corrosion; evaluating possibility biofilm formation. were first tested site (Mezőberény, SE Hungary, installed 2012) that had stop operation because unsuccessful reinjection. is consequence several separate their interaction: Reservoir insufficient due limited horizontal extension bodies. Precipitation carbonates, iron manganese minerals predicted hydrogeochemical models observed solid phase analysis. Microbial material produced from particularly high organic thermal water. hydraulic effects not expected since slightly subhydrostatic. summary, determine injectivity, which further decreased critical level processes. proposed generalized guides detailed system analysis essential operation.