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).



21.02.2018 10:12

AAPG ACE 2018 in Salt Lake City (19.-23.05.2018)

Gesteinslabor will present brandnew results from the frontline of research at one of the key events for petroleum geologists.

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21.02.2018 08:45

TSK 2018 in in Jena (21.-23.03.2018)

Gesteinslabor will take part at the distinguished conference dealing with tectonics, structural geology and crystalline rocks.

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31.01.2018 12:06

Spring meeting 2018 in Celle

Following a well established tradition, also in 2018 DGMK and ÖGEW will host their annual conference in the Congress Union Celle.

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