The TEST TANK FOR TRAPPING MECHANISMS (‘Test tank’ in short) is dedicated to the study of the dissolution trapping mechanisms in COR2R storage reservoirs. This trapping mechanism speeds up the transition to safe long-term storage since COR2R-rich water is heavier than COR2R-free water and will therefore sink to the bottom of the formation. Density convection currents that will be generated by the density difference will speed up considerably the dissolution of COR2R into formation water in a storage site, since they will enable continuous exposure of COR2R in the gas cap to formation water that is not already saturated with COR2R. The time until onset of convection is therefore an important parameter. The Test tank is designed for studies of this process under near reservoir conditions.
The Test tank is a cylindrical pressure vessel with 60 cm diameter and 60 cm height internal dimensions. It can be pressurised to near storage conditions (65 bar) to increase the solubility of COR2R in water compared to atmospheric conditions. Wetted materials used are resistant to COR2R/water systems. Specifically, the materials are resistant to the carbonic acid that forms when COR2R dissolves into water. The pressure vessel is equipped with a removable lid to enable filling of the interior of the pressure vessel with a porous medium to represent the storage formation.
The Test tank will support research on long term trapping mechanisms for COR2R in storage reservoirs. It is therefore relevant for research and demonstration of COR2R storage safety. The porous medium in the Test tank can be made to be homogeneous or heterogeneous, e.g. to study the effect of layering in storage reservoirs.
The Test tank can also be used for research into related fields such as gravity segregation during water flooding of heterogeneous oil reservoirs.
The pressure vessel itself, with supporting infrastructure, is the only installation for the Test tank. The supporting infrastructure consists of equipment for temperature control, a high precision two-cylinder COR2R pump for pressure stabilisation of the process volume during tests, and a computer that runs the control and logging software. The logged parameters are the pressure and temperature in the interior of the pressure vessel, as well as the pressure and temperature of the pump.
Earlier experiments designed for measuring the dissolution process and the onset of convection-enhanced dissolution have been restricted either to model systems that can be operated at atmospheric conditions, or at a smaller scale (15 cm). Experiments in bulk 3D on this scale has not previously been possible.
The Test tank is integrated into SINTEF's core flooding and reservoir fluid analysis laboratories. This allows a range of auxiliary tests, e.g. of the average permeability of the porous material used in the tank or solubility characteristics of any fluid systems used.