Need for experiments on shut-ins and depressurizations in CO₂ injection wells

Every CO₂ capture and storage chain will contain injection wells. The most important common operations for wells are shut-ins and depressurizations for reservoir characterization, maintenance stops and testing of valves. The aim of this work is firstly to demonstrate the need for experiments on these operations. Secondly, a new experimental set-up is proposed for such experiments. The main conclusion from this paper is that the physical phenomena during shut-ins and depressurizations of CO₂ injection wells can be described with models, but that that there are still some uncertainties left. The largest uncertainties occur when the transient flow is rapid and/or CO₂ is mixed with water. The proposed experimental set-up consists of a well with casing to be drilled vertically 200-250 meter at the Statoil laboratory in Trondheim, Norway. A U-tube with two legs with different diameter will be suspended in the well. Moreover, water or brine can be added for observing the effects of the H₂O-CO₂ interaction. The U-tube is to be linked to the existing CO₂ transport test facility, which has the necessary vessels, compressor and pump. This rig will hopefully contribute in making CO₂ injection wells even safer and more cost efficient.