Development of a test setup capable of producing hydraulic fracturing in the laboratory with image and acoustic emission monitoring

Hydrocarbon extraction is relying progressively more on hydraulic fracturing stimulation of shale. Enhanced Geothermal Systems (EGS) also rely on hydraulic fracturing to create fractures through which water is circulated to recover heat. While hydraulic fracturing has been extensively used in field applications, the fracturing processes involved in this method are still not well understood. Since data obtained from field hydraulic stimulations may be very difficult to interpret, laboratory testing can play a major role in understanding the way fractures initiate, propagate and interact when hydraulically stimulated. This paper describes a test setup developed at MIT, which allows one to apply hydraulic pressure to flaws, or existing fractures, leading to the initiation and propagation of fractures. The test setup consists of (1) an enclosure designed and built at MIT in which water pressures up to 10 MPa can be generated, (2) a high speed camera that captures the last seconds of a test at 14,000 frames per second, (3) a high resolution camera that captures frames every 2 to 5 seconds throughout a test, and (4) an acoustic emission system that monitors the micro-seismic activity throughout the test. The setup has been successfully used in several tests on granite. An example of the type of results obtained in a test is shown.