Stress determination from hydraulic test data and focal mechanisms of induced seismicity

Cornet, F. H.; Julien, Ph.

doi:10.1016/0148-9062(90)95047-5

Cited by 1 publication

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“…This geothermal reservoir, which acts as a heat exchange interface, is created by hydraulic fracturing. Since the fractures created by hydraulic fracturing at depth are controlled by the stress state and the permeability, the stress states at HDR test sites have been extensively estimated by using various methods such as the hydraulic fracturing method (e.g., CORNET and JULIEN, 1989), laboratory tests by the Acoustic Emission method (e.g., SHIN et al, 2000) and the Dierential Strain Curve Analysis method (DSCA) (e.g., OIKAWA et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

“…Results of monitoring of hydraulic fracturing experiments have been reported (e.g., JUPE et al, 1992;CORNET et al, 1997;PHILLIPS et al, 1997;SASAKI, 1998). The analysis of microseismic locations provides information on the fracture growth, the main¯ow direction, and the drilling target of a new well, while the focal mechanisms of the microseismic events provide other information on the stress state (e.g., CORNET and JULIEN, 1989;CORNET and YIN, 1995;TEZUKA and NIITSUMA, 2000).…”

Section: Introductionmentioning

confidence: 99%

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Determination of Stress State from Focal Mechanisms of Microseismic Events Induced During Hydraulic Injection at the Hijiori Hot Dry Rock Site

Sasaki¹,

Kaieda²

2002

Pure appl. geophys.

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Ð The stress state at the Hijiori hot dry rock site was estimated based on the inversion from focal mechanisms of microseismic events induced during hydraulic injection experiments. The best ®t stress model obtained by inverting 58 focal mechanisms of seismic events simultaneously indicates that the maximum principal stress r 1 is vertical, while the minimum principal stress r 3 is horizontal and trends north-south. The average mis®t between the stress model and all the data is 6.8°. The inversion results show that the average mis®t is small enough to satisfy the assumption of homogeneity in the focal mechanism data and that the 95% con®dence regions of r 1 and r 3 are well constrained, i.e., they do not overlap, suggesting that the inversion results are acceptable. The stress estimates obtained by the focal mechanism inversion essentially agree with other stress estimates previously obtained. It is therefore concluded that the focal mechanism inversion method provides a useful tool for estimating the stress state. The hypocentral distributions of microseismic events associated with the hydraulic fracturing experiments are distributed around the plane that spreads to almost east±west from the injection wells and declines to the north at a high angle. The vertical orientation and east±west strike of the seismic events are essentially coplanar with the caldera ring-fault structure in the southern portion of the Hijiori Caldera. This indicates that tensile fractures of intact rock were not being created, but pre-existing fractures were being re-opened and developed in the direction of the maximum horizontal principal stress, although microseismic events were caused by shear failures.

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Section: Introductionmentioning

confidence: 99%