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).

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23.06.2025 · SCAN

 

We are pleased to be part of the Dutch subsurface research for geothermal heat SCAN.

Further information can be found on the official homepage:

https://scanaardwarmte.nl/english/

 

03.10.2024 · Project HENRI

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.

 

01.12.2022 · 

Gesteinslabor has successfully completed the development of a new test rig to determine the capillary threshold pressure with hydrogen.