... ABSTRACT This study aims at improving our understanding on the stress field dominating the intersection between two tunnels of different diameter and hence provide insights on the stability against shear failures in this vicinity. Theoretical modeling of the deformation of rocks...

... ABSTRACT We investigate horizontal stress variation in the vicinity of the deep-seated Balarud Lineament in the northern part of Iran's Dezful Embayment in the Zagros Fold and Thrust Belt (ZFTB). Both petrophysical data from drilled oil and gas wells (3-4 km deep) and earthquake focal plane...

... be obtained only at discrete points – from seismic events analysis or wellbore data. This paper is focused on the latter – the problem of using wellbore data to understand the in-situ stresses at rock mass via estimating stresses existing in the well vicinity. estimation experiment consideration...

... tensional and compressional stress perturbation around the producing well in the vicinity of fracture tips and fracture walls while the stress is released as the well produces. In addition, the magnitude of stress variation in the well group increases with the depletion at the beginning, followed...

...ARMA 21 1148 Fluid Conductivity of Natural Shear Fractures in Vicinity of an Inclined Well Dubinya, N.V. Moscow Institute of Physics and Technology, Dolgoprudny, Moscow Region, Russian Federation Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences, Moscow, Russian...

... events occurrence when mining through the dyke. Increase in potency at the vicinity of the dyke was also noted. metals & mining strength Reservoir Characterization dyke material Artificial Intelligence vicinity seismic event Upstream Oil & Gas experiment Implementation stress...

... of the cavern. Results reveal the significant influences of idle time, gas pressure range, and injection and withdrawal cycles on stress, strain and temperature distributions in the vicinity of the cavern. More analyses are needed to confirm the influence of thermo-mechanical cycles of pressurization...

... ABSTRACT: Pore pressure reduction, caused by reservoir fluid production, will alter the stresses in the vicinity of a producer. These stress alterations affect the propagation of hydraulic fractures that originate e.g. during water or polymer injection into injector wells as part of enhanced...

... in response to fluid injection and heat extraction processes. Using a Laplace domain Green s function approach, the solutions for pore pressure and temperature inside the fracture and its vicinity are derived. A numerical simulation is carried out to analyze the sensitivity of the solution to different...

... expected repository conditions the volume closure and the compaction of the backfill are mainly influenced by the temperature increase and the pre-excavation lithostatic stress at the waste emplacement level. radioactive waste rock salt Reservoir Characterization vicinity repository concept...

... and maximize the ore recovery. A number of factors may influence the stability of the open stope such as mining depth, the strength and quality of the rock mass and backfill, the stope size, and the presence of major geological structures in the vicinity of the mined stope. There have been many studies...

... < TF cases, respectively. If only the thermally induced pore pressure are considered, then it can be shown that heating induces positive (increases) pore pressure, while cooling induces negative (decreases) pore pressure in the formation. The change of the pore pressure near the wellbore wall is large at short times after drilling; however, it decreases with longer times and moves farther into the formation. It can also be shown that heating induces compressive radial stresses in the vicinity of the borehole wall and significantly more compressive tangential stresses at the wall; and vice versa (see section 4.4). 4.2. Effects of Permeability and Fluid Viscosity Fig. 3 portrays pore pressure distributions for various ratios of permeability/fluid viscosity, k/ = 10-15 (green), 10-16 (blue), and 10-17 (red) m2/Pa.s, for the heating case. The properties in Table 1 and the input parameters in Table 2 are assumed. It is shown that the lower the ratio, the larger the thermal loading effect on the pore pressure changes in the vicinity of the borehole. That is, the lower the ratio, the higher the maximum value attained by the pore pressure in the formation for the heating case, and the lower the minimum value attained by the pore pressure in the formation for the cooling case. 4.3. Pore Pressure Distributions The pore pressure distributions at and in the vicinity of the borehole wall for the isothermal (blue), heating (green), and cooling (red) cases are shown in Fig. 4. The properties in Table 1, with k/ = 10-17 m2/Pa.s, and the input parameters in Table 2 are assumed. For the isothermal case (TB = TF = 135 oC), the pore pressure is equal to the mud pressure, pB = 60 MPa, at the borehole wall, and decays toward the formation pore pressure, pF = 52 MPa, at large radii. For the heating case (TB = 185 oC, TF = 135 oC), the pore pressure increases away from the wall, reaching a maximum value inside the formation, before decaying to pF at large radii. For the cooling case (TB = 85 oC, TF = 135 oC), the pore pressure decreases away from the wall, reaching a minimum value below pF inside the formation. That is, heating induces an increase in the pore pressure, while cooling induces a decrease in the pore pressure in the vicinity of the borehole. 4.4. Total Stress Distributions The distributions of radial and tangential total stresses in the formation around the wellbore for the isothermal (blue), heating (green), and cooling (red) cases are shown in Figs. 5 and 6. The properties in Table 1, with k/ = 10-17 m2/Pa.s, and the input parameters in Table 2 are assumed. The radial total stresses is equal to the mud pressure (60 MPa) at the borehole wall and increase (become more compressive) nonlinearly in the formation towards the far field stresses (91 MPa). On the other hand, the tangential total stresses are significantly more compressive at the borehole wall and decrease (become less compressive) nonlinearly in the formation towards the far field stresses (91 MPa). At the wall and in the vicinity of the borehole heating increases the tangential total stress; while cooling decreases the tangential total stress relative to the isothermal case. The maximum value of the tangential total stress at the wellbore wall is higher for heating than cooling. It can be seen that heating induces more compressive radial total stresses and more compressive tangential total stresses near the wellbore. The total radial and tangential stresses are more compressive in the case of heating and less compressive in the case of cooling, relative to the isothermal case. 4.5. Full Coupling Effect Fig. 7 compares the pore pressure distributions of the fully (blue) and partially (red) coupled thermoporoelastic models for the heating case. The properties in Table 1, with k/ = 10-17 m2/Pa.s, and the input parameters in Table 2 are assumed (hydrostatic case). The partially coupled model comprises an uncoupled heat diffusion equation that is solely a function of temperature, and the absence of indirect flows: thermal osmosis and pressure thermal effect. The rate of change of the entropy of the rock is solely proportional to the rate of change of temperature. The partially coupled model overestimates the pore pressure for the heating case, and underestimates the pore pressure for the cooling case. Table 1. Physical properties of the rock/fluid system Drained Elastic modulus, E 45 x 109 Pa Solid bulk modulus, Ks 65 x 109 Pa Drained Poisson s Ratio, 0.27 Permeability/Fluid viscosity ratios, k/ 10-15, 10-16, 10-17 m2/Pa.s Reference Porosity, 0.15 Fluid density, f 1111 kg/m 3 Fluid specific heat capacity, Cf 4186 J/Kg.oK Fluid bulk modulus Kf 3.3 x 109 Pa Fluid volumetric thermal expansion coefficient, f 3 x 10-4 oK-1 Solid density, s 2.83 × 10 3 kg/m3 Solid specific heat capacity, Cs 920 J/Kg.oK Solid volumetric thermal expansion coefficient, s 2.4 x 10-5 oK-1 Rock thermal conductivity coefficient, kT 4 W/m. oK Thermal osmosis coefficient, KT 10-11 m2/s. oK Solute molar mass, MS 0.1111 kg/m3 Solute reflected fraction, 0.01, 0.15 Solute chemical diffusion coefficient, D 10-9 m2/s Solute thermal diffusion coefficient, DT 10-10 m2/s. oK Chemical stress coupling parameter, 100 kg/m3 Table 2. Input parameters for Examples In situ hydrostatic stresses, x = y 91 Mpa (Therm. Ex.) 88.5 MPa (Chem. Ex.) In situ non-hydrostatic stresses, x = 91 Mpa y = 86 Mpa In situ formation pore pressure, pF 52 MPa Mud pressure, pB 60 MPa Mud solute mass fraction, CB 0.1, 0.2 Reference formation solute mass fraction, CF 0.2, 0.1 In situ formation temperature, TF 135 oC Mud Temperature, TB 85 oC, 185 oC Wellbore radius, r0 0.1 m Fig. 1. Induced pore pressure distribution around the borehole for the heating case due to thermal loading. Fig. 2. Induced pore pressure distribution around the borehole for the cooling case due to thermal loading. Fig. 3 Effect of permeability/viscosity ratios on pore pressure distributions for the heating case. Fig. 4 Pore pressure distributions around the borehole for the isothermal (blue), heating (green), and cooling (red) cases. Fig. 5 Radial total stress distributions for the isothermal (blue), heating (green), and cooling (red) cases. Fig. 6 Tangential total stress distributions for the isothermal (blue), heating (green), and cooling (red) cases. Fig. 7 Pore pressure distributions of the fully-coupled (blue) and partially-coupled models (red) for the heating case. 5. CHEMICAL THERMOPOROELASTIC EXAMPLES 5.1. Effects of Chemical Loading Consider an example involving a radially symmetric TCPu system where we isolate the effects of chemical loading on the pore pressure and total stresses. In other words, we load the system with a solute mass fraction difference between the mud or borehole and the formation, and observe the resulting induced pore pressure and total stresses around the wellbore. In this example, all the processes are in play: thermoporoelastic deformation, chemical swelling, hydraulic conduction, chemical osmosis, thermal osmosis, solute pressure diffusion, solute chemical diffusion, solute thermal diffusion, heat conduction, pressure thermal effect, chemo-thermal effect, and the interconvertibility of mechanical, chemical, and thermal energy. It is assumed that initially all the pore pressures and stresses are zero, TB = TF = 135 oC, and the rock-fluid properties are displayed in Table 1, with k/ = 10-16 m2/Pa.s, = 0.15, and = 100 kg/m3. Results are portrayed in Figs. 8 and 9, for the induced pore pressure by chemical loading. The different curves correspond to times 2 (blue), 6 (green), 12 (red), and 24 (cyan) hours. If only the chemically induced pore pressure are considered, then it can be shown that lower mud solute concentration induces positive (increases) pore pressure, while higher mud solute concentration induces negative (decreases) pore pressure in the formation. It can also be shown that lower mud solute concentration induces compressive radial stresses in the vicinity of the borehole wall and significantly more compressive tangential stresses at the wall; and vice versa (see section 5.4). 5.2. Effects of Permeability and Fluid Viscosity Consider a radially symmetric non-isothermal chemoporoelastic system, TCPu. Fig. 10 portrays pore pressure distributions for various ratios of permeability/fluid viscosity, k/ = 10-15 (green), 10-16 (blue), and 10-17 (red) m2/Pa.s, for the higher mud solute concentration CB > CF case, after t = 12 hours. The properties in Table 1 with = 0.01, and the input parameters in Table 2 (hydrostatic case) are assumed with TB = TF = 135 oC. It is shown that the lower the ratio, the larger the chemical loading effect on the pore pressure changes in the vicinity of the borehole...

... for the large excavations based on the data available to date. INTRODUCTION Reservoir Characterization Upstream Oil &amp; Gas vicinity reservoir geomechanics preliminary design metals &amp; mining classification information mapping evaluation Homestake investigation deep underground...

... reservoir geomechanics Upstream Oil &amp; Gas vicinity hydraulic fracturing aperture Reservoir Characterization Wellbore Design fracture aperture rock failure poroelastic rock failure analysis failure criterion flow in porous media Fluid Dynamics pore pressure matrix fracture...

...) opening mode and in providing crustal information for establishing the Cenozoic crustal evolution history in the East Asia. It is also expected to provide basic geological information to develop natural resources in the vicinity of East Sea. Tsushima Island is located in the Korea Strait between...

... these two effects. Numerical results indicate that induced seismic events have magnitudes characteristic of microseismicity, and most of them occur in the close vicinity of the fracture front. The analysis of events shows that their grouping allows for defining the fracture plane, while the central line...

... into the following categories: Fracture in-situ: <1 % Breakage: 15% Displacement: 4% Crushing in the vicinity of the blasthole: 1.5 to 2% Fly-rock: <1% Deformation of solid rock behind the shot: <1% Ground vibrations: 40% Air blast/noise : 38 to 39 % Many researchers have studied the influence of fragmentation...

... with generating heat. The authors made an experiment to fracture a mortar specimen of 300 mm cube by setting expansive cement in a 50 mm diameter hole bored in the center of the specimen. Located AE (acoustic emission) sources clustered in the middle of a lateral surface and the hole rather than the vicinity...

... representation of the stress field around the crack tip in a vicinity of an interface is extracted from the exact solution. Particularly, the SIF Green's function due to the unit double force applied at the crack faces is derived for arbitrary distance s of the crack tip from the interface. This paper also...

... &amp; mining vicinity Pariseau Upstream Oil &amp; Gas joint segment influence function average strain rectangular entry equivalent property roof beam jointed rock mass horizontal joint rock mass classical solution single element failure mechanism Rock Mechamcs tn the Nattonal Interest...