Triaxial compression test accompanied by ultrasonic and permeability measurements
A specimen of the low permeability and low porosity Dethlingen Sandstone (k: 0.04 mD, φ: 4.5%) was exposed to a low confining pressure of 10 MPa and a peak axial stress of 250 MPa. The test run is displayed in the graph below. While the stress-strain curve (in green) still takes an apparently linear course, the shear wave velocity (red crosses) is the first to exceed a maximum and subsequently slows down. This reflects the beginning of micro crack formation, and the resulting inner destruction of the sample cylinder. As soon as the micro cracks start to connect, P waves (pink triangles) also decelerate and permeability (to gas ; blue curve) increases instantaneously. From the relationship of the velocity changes between the P and S wave it can be inferred that fracturing follows the main compressive stress σ1 and that the micro cracks are oriented perpendicular to the least principle stress σ3 (for details see (Braun & Jahns 1998).
News
Meet us at the GET 2024
Gesteinslabor will exhibit at the GET2024 in Rotterdam. 4.-7.November 2024, find us at booth 605.
We are looking forward meeting you there!
Gesteinslabor Dr. Eberhard Jahns is project and research partner within the HENRI (Hydrogen Energy Reservoir) project.
Main focus of us is the impact of H2 on the cap rock. Besides other parameters, we determine the capillary threshold pressure with different gases and gas mixtures.
First preliminary results could be presented at the 2nd HENRI conference.
Recently, the article "Determination of capillary threshold pressure with hydrogen gas" was published in the journal EEK.
Article from the journal EEK 01/2023
Gesteinslabor has successfully completed the development of a new test rig to determine the capillary threshold pressure with hydrogen.
Read more … Determination of capillary threshold pressure using hydrogen gas