Simultaneous Treatment and Remote Well Monitoring of Microseismicity from a Hydraulic Fracture

In June 2006, in a sandstone-shale sequence in the western USA, two borehole seismic arrays were deployed to record and map the source locations of the microseismicity created by a hydraulic fracture treatment. The intent was to use the microseismic locations from each array as an overlay to map the hydraulic fracture network and compare the maps from the two deployments. The first array was in a remote well ~210 m from the treatment well and at the treatment depth. This array was ~150 m long, self-locking, contained 15 levels of 3-component sensors, and required external sources to orient the sensors. The second array, the “TABS” or TriAxial Borehole Seismic array, was deployed in the treatment well during and following the proppant-baring treatment. TABS is ~23 m long, contains 3, 3-component sensors, is self-locking, and includes a sensor orientation package. During the operation, a 45-minute injection followed by a 1-1/2-hour post treatment monitoring, the offset array failed to detect any discernable, useful signals – subsequent processing may pull signals from the noise. Comparatively, TABS, which monitored only during the post-treatment, recorded ~400 events without subsequent processing.