Passive seismic measurement of seismic attenuation in Delaware Basin

Abstract

Local earthquake activity can be employed to measure attenuation (the effective quality factor [Q]) and characterize production in the Delaware Basin, Texas, USA. To illustrate this, we employed data from the recently installed Texas Seismic Network (TexNet) seismic stations collected in the west Texas area between April 2017 and March 2018. Earthquake activity in the Delaware Basin has increased in comparison to the previous 20 years, which has resulted in numerous high-quality events suitable for this analysis. The high signal-to-noise ratio events were used to estimate effective Q factors using the peak frequency method on the sediments of the Delaware Basin. The effective attenuation of the sedimentary basin is 90 for P-waves and 140 for S-waves (both with uncertainty of approximately 30), indicating an unusually low attenuation (high Q) for S-waves relative to the P-waves. This is consistent with attenuation of a saturated sedimentary basin because the saturation results in less attenuation of S-waves. Additionally, we observe an increase of the effective Q factor with distance between the station and events consistent with rays sampling the deeper, less-attenuating, and less-saturated portions of the basin and even basement. Inverted effective attenuation coefficients were used to calculate moment magnitudes, which were consistent with those seen in the TexNet array.

Estimation of the quality factor based on the microseismicity recordings from Northern Poland

“…We show that the observed peak frequency across both fractured reservoirs is consistent with being homogenous and isotropic. Estimated P-and S-wave quality factors in both studied datasets are in general agreement with the results obtained by other authors (Wcisło and Eisner 2016;Jyothi et al 2017;Drwiła et al 2019). In both cases, we observe elevated values of Q for the S wave relative to Q for P wave, which is typical for the highly compacted and saturated sedimentary reservoirs (Pham et al 2002).…”

“…Attenuation can be described as the frictional energy loss per cycle (Aki and Richards 2002), and it is routinely measured in VSP experiments (e.g., Rutledge and Winkler 1989) or estimated from sonic logs (e.g., Liner 2014). Drwiła et al (2019) showed that incorporating attenuation measurements is also an important factor in the calculation of the moment magnitudes of the recorded events. In addition, the quality factor obtained from microseismicity can be also of use in the performance evaluation of the monitoring networks (Wandycz et al 2018).…”

Mapping the 3‐D Lithospheric Structure of the Greater Permian Basin in West Texas and Southeast New Mexico for Earthquake Monitoring

“…Journal of Geophysical Research: Solid Earth anomalies suggests that the feature of lower V p /V s ratios is strongly associated with the content of a sedimentary basin characterized by porous and gas/fluid-saturated host rocks with a low density (e.g., Adams & Keller, 1996). A recent study by Drwiła et al (2019) of Qp and Qs of the Delaware Basin provides additional evidence that V p attenuates faster than V s and further lowers the V p /V s ratio. Their results show that Qp = 91 and Qs = 139 for the entire Delaware Basin where the V p /V s ratio shown is commonly lower in our tomography model.…”