Comparison of simultaneous downhole and surface microseismic monitoring in the Williston Basin

Abstract

Microseismic events reported from simultaneous downhole and surface monitoring of a hydraulic fracture well stimulation were matched on an event‐by‐event basis and compared. Downhole monitoring was much more sensitive than surface monitoring near the observation well, detecting 4–5 times the number of events, but the downhole monitoring appeared to be lose much of it sensitivity advantage at distances greater than about 3,000 feet. The picks reported from surface monitoring varied dramatically depending on the picking criteria that were used, which emphasizes the need for a reliable pick confidence factor. In the strict assessment of the surface data the existence of the majority of the events were corroborated by the downhole data, including many sub‐visible surface events. Considerable differences exist in the reported spatial location of the events picked by the two methods despite correct positioning of perforation shots for each method. The events picked by the surface method are clustered much more closely to the wellbore, which may represent a considerably lower estimate of the stimulated rock volume.