Geothermal Reinjection Well Injectivity Index (II) Calculator
Determine the Injectivity Index (II) in tons/h/bar, required surface pump pressure, and thermal stress contraction permeability enhancement for disposal wells.
Reinjection Operating Conditions
Injectivity & Surface Pumping Head
Recommended Tools & Equipment
Tested hardware and components for high reliability
Frequently Asked Questions
What is the Injectivity Index (II) of a geothermal reinjection well?
Injectivity Index II = Q / (P_wellbore - P_reservoir) measures the flow rate of cooled brine accepted by the formation per unit of bottomhole overpressure, typically expressed in tons per hour per bar (t/h/bar).
Why does cold brine injection increase well injectivity over time (thermal stimulation)?
Injecting relatively cold brine (60°C–90°C) into hot reservoir rock (200°C–300°C) causes substantial thermo-elastic contraction of matrix rock, opening existing natural fracture apertures and creating self-propagating micro-fractures.
Why can some geothermal reinjection wells operate under vacuum at the wellhead?
Because cold water (970–1000 kg/m³) is much denser than the hot reservoir fluid column (~750–850 kg/m³), the hydrostatic weight of the injection column exceeds reservoir pressure, sucking brine underground by pure gravity.