In-Situ AE Measurement of Hydraulic Fracturing at Geothermal Fields

Abstract

A triaxial acceleration-sense down-hole AE measurement system was developed and successfully applied to the monitoring of both man-made and natural hydraulic fracture in a geothermal field. The accelerationsense instrumentation allows long-distance measurement of subsurface crack extension.AE events during hydraulic fracturing in Nigorikawa geothermal field could be detected at a distance of l600m from the AE source. AE events during a closure operation of a well-head valve in the Kakkonda geothermal field could also be detected by the system. In this paper, the feasibility of the simple measurement system for in-situ monitoring of subsurface crack extension in a geothermal field is demonstrated with reference to the fracture mechanics model of a geothermal reservoir.