Use of Surface Seismic Patches for Hydraulic Fracture Monitoring

In 2011 Schlumberger and an independent operator jointly acquired a comprehensive dataset of hydraulic fracturing operations which stimulated the Fayetteville shale: signal and noise were tracked from reservoir to surface and then across the surface. The performance of alternative monitoring technologies such as surface and shallow borehole seismic arrays as well as a downhole seismic array are analyzed. The noise levels on the different seismic arrays are characterized and appropriate attenuation techniques are applied. Furthermore linear and non-linear stacking methods are utilized to increase the signal-to-noise ratio (SNR). The application of the Coalescense Microseismic Mapping algorithm to locate microseismic events concludes that an accurate source location requires an accurate velocity model together with consistent and aligned signal. Coherent noise, insufficient signal or noise discrimination are key factors influencing location uncertainty. Although surface line segments benefit from larger receiver apertures, SNRs of their stacks were usually only slightly higher than from stacks of surface patches using linear stacking methods. However, source localization is more accurate using surface lines. Nevertheless, surface patches are easily deployable so provided sufficient signal is recorded and noise attenuation methods are applied prior to stacking and source scanning, they may ultimately become the preferred surface monitoring configuration.