Two methods for hydraulic fracturing stress measurements without the ambiguous reopening pressure

Two methods which do not use the ambiguous reopening pressure for hydraulic fracturing stress measurement are presented. The first method uses only the shut-in pressures for the transverse cracks crossing the borehole obliquely, and the second method uses the actual reopening pressure of the longitudinal crack, which coincides actually with the reopening of the crack lip at the borehole wall. The first method can estimate the range of error in the evaluated magnitudes and orientations of the remote stresses. The two methods are applied to the results of hydraulic fracturing experiments performed at the Kamaishi mine. Reliability of the evaluated stress field is confirmed by comparing the stress field with that evaluated by the over coring method. From these results, the effects of fault on the stress field are also discussed.