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Probing Frictional Properties of Delaware Basin Formations: Insights From Laboratory Experiments

Description: 

The Delaware Basin in west Texas/SE New Mexico, is one of the most hydrocarbon productive and tectonically complex basins in the US. This intraplate region has experienced a dramatic increase in seismic rates since 2016, a phenomenon linked to waste-water disposal and hydraulic fracturing into shallow and deep formations. However, details of the connection between industry practices and seismicity are unclear. In the central basin, earthquakes are small-to-moderate magnitude and confined at shallow depths (2-3 km) corresponding to injection layers, suggesting a causal relationship. To the north, seismicity is characterized by larger magnitudes (up to Mw=5) involving deeper formations down to the crystalline basement (average depth ~6.5 km), despite most of the fluid disposal volume being injected into shallow formations. Seismological studies integrated with InSAR information reveal that seismicity accounts for no more than 5% of the total deformation, suggesting that the remainder is accommodated aseismically.
To investigate the control of lithology on the distribution of seismicity, we tested the frictional properties of 11 lithologies of the Delaware Basin from the crystalline basement to the Delaware Mountain Group. We characterized the steady-state friction and velocity dependence of friction using a biaxial apparatus in a double direct shear configuration, at normal stresses of 20, 40 and 60 MPa. The friction coefficient µ ranges between 0.33 and 0.66, with phyllosilicate content controlling the weakness of the fault. Frictional stability increases with phyllosilicate content. In general, the rate parameter (a-b) shows good agreement with seismicity depth distribution. We suggest that phyllosilicate-rich formations—where sufficiently thick—act as a seal to fluids and a barrier to earthquake propagation. Where these are absent or thinned, seismic instabilities can extend deeper, reactivating basement faults. Together, these results demonstrate how the lithological architecture of the basin, combined with its structural and mechanical properties control the depth and magnitude of induced seismicity.

Session: Mechanistic Insights into Fluid-induced Earthquakes from the Laboratory to the Field - I

Type: Oral

Date: 4/15/2025

Presentation Time: 03:00 PM (local time)

Presenting Author: Maria Beatrice

Student Presenter: No

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