목차

1. INTRODUCTION 1
1.1. Overview 1
1.2. Integrated and site-specific stress estimations 2
2. REVIEW OF LITERATURE 6
2.1. In situ stress states in subsurface and their determinations 7
2.2. Stress conditions in the vicinity of a vertical borehole 9
2.2.1. Drilling induced stress concentration around circular hole 9
2.2.2. Effective stress conditions at the borehole wall 10
2.3. Estimation of the states of horizontal principal stress using a vertical borehole 14
2.3.1. Hydraulic fracturing stress measurement 14
2.3.2. Borehole wall failure analyses 22
2.4. Further studies on the mechanical properties of rock related with reliable estimations of magnitude of SHmax 27
2.4.1. Hydraulic fracturing tensile strength 27
2.4.2. Effective compressive strength under borehole wall condition 30
3. KURT STUDY SITE 34
3.1. General 34
3.2. Geological environments 35
3.3. Borehole Investigations 39
4. IN SITU STRESS ESTIMATIONS 42
4.1. Tested boreholes for stress measurements 42
4.2. Stress orientations 46
4.2.1. Hydraulic fracturing tests 46
4.2.2. Borehole wall failures 54
4.3. Stress magnitudes 60
4.3.1. Vertical stress 60
4.3.2. Stress estimates from hydraulic fracturing results 60
4.3.3. Stress estimates from borehole wall failures 65
5. LOCAL SCALE STRESS FEATURES OF KURT STUDY SITE 74
5.1. Stress profile 74
5.2. Comparison with regional-scale stress condition 79
6. IMPLICATIONS OF THE STRESS STATE FOR GEOMECHANICAL AND GEOLOGICAL CONDITIONS 87
6.1. Geomechanical risk assessment of the natural fractures and faults at KURT study site 87
6.2. Influence factors on hydraulic conductivity of fractured rock domain statistical analysis 100
7. DISCUSSION AND CONCLUSIONS 113
REFERENCES 117
APPENDIX 137
I. Pressure-time curves obtained from hydraulic fracturing test in boreholes YS-4 and DB-2 137
II. Traces of hydraulically induced vertical fractures 141
III. Shut-in pressure determinations 144
ABSTRACT(국문초록) 146