Measuring the physical properties of rocks under simulated “in situ” conditions in the laboratory is crucial for a comprehensive characterization of natural geological reservoirs. The long-term flow-through apparatus SEPP consists of a total of 6 temperature-controlled oil pressure chambers, whose internal set-up allows combined measurements of permeability, P and S wave velocity, and complex electrical conductivity (leakage current-free 4-pole measurements) on rock cylinders (d = 25/30 mm, l_max = 60 mm). In case a hydrophilic porous membrane is placed between sample and lower measuring head, the device can also be used to determine capillary pressure curves both at drainage and imbibition. Sample holders/ measuring heads made from Hastelloy C276 allow for the use of highly corrosive pore fluids, such as brines and weak acids. In addition, a hydraulic punch is integrated into the lower plug of the pressure vessel, allowing for the application of bi-axial stress conditions.

The pressure vessels are designed for a maximum confining pressure of 60 MPa at a working temperature of 150 °C and thus allow experiments under simulated conditions of underground storage in 1000 - 3000 m depth. Generally, test conditions in a temperature range of -20 to 200 °C can be applied at a correspondingly lower confining pressure. For temperature control, the pressure vessels are equipped either with cooling jackets or oil-filled heating jackets. The pore fluid system for long-term flow tests is dimensioned for a maximum pore pressure of 40 MPa. To perform capillary pressure experiments, the injection system can be replaced by a displacement spindle pump (p_max = 30 MPa, T_max = 150 °C).