Half-moon events are the predominately observed source mechanism during hydraulic fracturing. We explain, that special stress conditions are needed to produce these events, for instance close principal stresses and notable shear stresses. Using a numerical simulation we show how these conditions are created during hydraulic stimulation. Depending on the stress regime, dip-slip events can be explained by slip on horizontal fault planes in strike-slip environments and by slip on vertical fault planes in normal faulting domains. Due to local rotations of the stress field, these fault orientations can become favorable oriented. Thereby, we can explain the frequent observation, that we see predominately half-moon events after the start of injection and opposed mechanisms at upper and lower layer interfaces.
Presentation Date: Wednesday, September 18, 2019
Session Start Time: 9:20 AM
Presentation Time: 9:20 AM
Location: Poster Station 9
Presentation Type: Poster