Page 9 - Reservoir Geomechanics

viii Contents

Elasticity anisotropy 65
Poroelasticity and effective stress 65
Poroelasticity and dispersion 69
Viscous deformation in uncemented sands 72
Thermoporoelasticity 83

4 Rock failure in compression, tension and shear 84

Rock strength in compression 87
Compressive strength criteria 92
Strength and pore pressure 104
Rock strength anisotropy 105
Estimating rock strength from geophysical log data 107
Shear-enhanced compaction 118
Tensile rock failure 121
Shear failure and the frictional strength of rocks 123
The critically stressed crust 127
Limits on in situ stress from the frictional strength of faults 130
Stress polygon 137

5 Faults and fractures at depth 140

Faults, fractures and fluid flow 142
Wellbore imaging 146
Representation of fracture and fault data at depth 149
Three-dimensional Mohr diagrams 154
Earthquake focal mechanisms 158

PART II: MEASURING STRESS ORIENTATION AND
MAGNITUDE

6 Compressive and tensile failures in vertical wells 167

Stress concentration around a cylindrical hole and wellbore failure 169
Quality ranking system for stress indicators 187