how do we know the caprock will act as a safe seal? and what if it's faulted?

An extensive shaly impermeable caprock overlies the reservoir and prevents any untrapped CO2 from continuing to rise upwards and escaping. Various caprock leakage scenarios are studied in detail with predictions made over long time scales, namely: 1) mechanical stability: if the rock is fractured or if existing faults are reactivated by pressure injection; 2) geochemistry: e.g. if the fault plane seal is weakened by acidification in the presence of CO2.

ULTimateCO2 research aims to calculate the impact of such scenarios over time: e.g. numerical modeling to predict the CO2 escape paths, dissolution rates, increases/decreases in permeability, etc.; comparison with previous data from gas reservoirs in the North Sea that have shown leakage; laboratory tests on shale caprock cores altered by geochemical acidification.

Dernière mise à jour le 12.05.2014