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Pore shape evolution by solution transfer: thermodynamics and mechanics
II8A
893088 Anisotropy in jointed rock mass breakage Chappell, B A Min Sci Technol VS, NI, Jan 1989, P1-19 Closed cracks in a rock mass have no volume effect on its deformation characteristics, but do affect strength. Joints, however, have a volume effect on the rock mass as well as on its strength or stability. Deformation moduli are expressed in terms of equilibrium and compatibility models for complete definition of rock mass deformation. For joints it is shown that both models are required to define the rock mass deformation characteristics, whilst for cracks only the equilibrium model is required. Joint shear strength and Griffith crack energy initiation criteria are then incorporated to obtain Griffith strength loci (both for shear and pseudo-Young's rock mass modulo for hard and soft rock masses. For hard rocks, the strength loci are significantly different, whilst for soft rocks they are similar, suggesting the soft rock mass has minimal size effects.
893089 Modeling of the stability of highly inclined boreholes in anisotropic rock formations Aadnoy, B S SPE Drilling Engng V3, N3, Sept 1988, P259-268 Two mathematical models, A N I S F R A C and ANISCOLL, for borehole fracturing and collapse respectively, are described. They include directional properties of real rocks and an anisotropic stress field. Borehole orientation, in situ stress, and bedding plane can be altered relative to each other to simulate real field conditions. Some results are presented, which demonstrate that neglecting effects of anisotropy introduces errors.
89309O Statistical analysis of the joint physical field measurements during the process of deformation and failure of large-scale rock blocks Sobolev, G A; Baddari, K; Frolov, A D Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug-lO Sept 1987 V2, P1237-1239. Publ Rotterdam." A A Balkema, 1987 Microfracturing will occur during deformation of rocks, but the inhomogeneous nature of geological materials makes interpretation of microfracturing data difficult. The physi¢al parameters, facet plane strain tensor, longitudinal elastic wave velocity, acoustic emission, resistivity and electric potential were monitored during loading of granite and dolerite blocks. An attempt is made to interpret measurements of individual parameters using statistical analysis to identify precursors of fracture at an early stage.
893092 Considerations on failure initiation in inclined boreholes Roegiers, J C; Detournay, E Key Questions in Rock Mechanics: Proc 29th US Symposium, .~linneapolis, 13-15 June 1988 P461-469. Publ Rotterdam: A A Balkema. 1988 The geometry created by hydraulic fracturing in an inclined borehole is little understood. Added complications introduced by the inclination of the borehole with respect to in situ principal stress directions are analysed, and the implication of deviated wells with regard to completion and stimulation are discussed.
893093 Conceptual and numerical models of high pressure fluid-rock interaction Pine, R J; Nicol, D A C Key Questions in Rock Mechanics: Proe 29th US Symposium, Minneapolis, 13-15 June 1988 P495-502. Publ Rotterdam." A A Balkema, 1988 Modelling of interaction of high pressure fluids within stressed rock masses is important to understanding permeability enhancement for geothermal reservoirs and similar situations. Current models are outlined,current understanding is discussed, and immediate and long term improvements are considered, all within limits imposed by the complex environment of a stressed rock mass. Conclusions indicate that interactive models must currently be limited to simple joint geometries in three dimensions.
Time dependent behaviour See also." 893247, 893427 893094 Pore shape evolution by solution transfer: thermodynamics and mechanics Reuschle, T; Trotignon, L; Gueguen, Y Geophys J V95, N3, Dec 1988, P535-547 Solution transfer creep is an important mechanism of deformation of the earth crust. Theoretical and laboratory simulations have not yet entirely clarified the process, as assumptions made may not be met by rock under natural stress. The deformation of a circular pore under constant biaxial stress and filled with a fluid under pressure is re-examined, concentrating on energy balance rather than kinetics. Results are used to simulate numerically the evolution of pore shape in the earth c rus t .
893091 Numerical analysis of multiple radial fracturing Christianson, bl C; Hart, R D; Schatz, J F Key Questions in Rock Mechanics: Proc 29th US Symposium, Minneapolis, 13-15 June 1988 P441-451. Publ Rotterdam: A A Balkema. 1988 Multiple radial fracturing due to explosive gas generation in low permeability gas bearing rocks has been modelled. The boundary element code G R I F F was used to model gas generation. Borehole pressurisation, fracture propagation, fracture curvature, gas flow, gas leakage, thermal quenching, and fracture arrest are simulated. Measurable material properties are input. Results are compared with field measurements, and indicate fractures curve less than assumed, and that conditions for long fracture propagation are difficult to maintain.
893095 Device for evaluating one-dimensional compressive loading rate effects Farr, J V; Woods, R D Geoteeh Test J VII, N4, Dec 1988, P269-275 An explosive-loaded uniaxial strain device, developed to measure loading rate effects for times to peak pressure ranging from a few minutes to less than a millisecond, is described. Results obtained from the new device and a conventional uniaxial strain cell for partially saturated carbonate sand show progressive stiffening of uniaxial strain response occurs as time to peak pressure decreases, and basic shape of the stress strain curve is maintained.
1989 Pergamon Press plc. Reproduction not permitted
893088 Anisotropy in jointed rock mass breakage Chappell, B A Min Sci Technol VS, NI, Jan 1989, P1-19 Closed cracks in a rock mass have no volume effect on its deformation characteristics, but do affect strength. Joints, however, have a volume effect on the rock mass as well as on its strength or stability. Deformation moduli are expressed in terms of equilibrium and compatibility models for complete definition of rock mass deformation. For joints it is shown that both models are required to define the rock mass deformation characteristics, whilst for cracks only the equilibrium model is required. Joint shear strength and Griffith crack energy initiation criteria are then incorporated to obtain Griffith strength loci (both for shear and pseudo-Young's rock mass modulo for hard and soft rock masses. For hard rocks, the strength loci are significantly different, whilst for soft rocks they are similar, suggesting the soft rock mass has minimal size effects.
893089 Modeling of the stability of highly inclined boreholes in anisotropic rock formations Aadnoy, B S SPE Drilling Engng V3, N3, Sept 1988, P259-268 Two mathematical models, A N I S F R A C and ANISCOLL, for borehole fracturing and collapse respectively, are described. They include directional properties of real rocks and an anisotropic stress field. Borehole orientation, in situ stress, and bedding plane can be altered relative to each other to simulate real field conditions. Some results are presented, which demonstrate that neglecting effects of anisotropy introduces errors.
89309O Statistical analysis of the joint physical field measurements during the process of deformation and failure of large-scale rock blocks Sobolev, G A; Baddari, K; Frolov, A D Proc 6th International Conference on Rock Mechanics, Montreal, 30 Aug-lO Sept 1987 V2, P1237-1239. Publ Rotterdam." A A Balkema, 1987 Microfracturing will occur during deformation of rocks, but the inhomogeneous nature of geological materials makes interpretation of microfracturing data difficult. The physi¢al parameters, facet plane strain tensor, longitudinal elastic wave velocity, acoustic emission, resistivity and electric potential were monitored during loading of granite and dolerite blocks. An attempt is made to interpret measurements of individual parameters using statistical analysis to identify precursors of fracture at an early stage.
893092 Considerations on failure initiation in inclined boreholes Roegiers, J C; Detournay, E Key Questions in Rock Mechanics: Proc 29th US Symposium, .~linneapolis, 13-15 June 1988 P461-469. Publ Rotterdam: A A Balkema. 1988 The geometry created by hydraulic fracturing in an inclined borehole is little understood. Added complications introduced by the inclination of the borehole with respect to in situ principal stress directions are analysed, and the implication of deviated wells with regard to completion and stimulation are discussed.
893093 Conceptual and numerical models of high pressure fluid-rock interaction Pine, R J; Nicol, D A C Key Questions in Rock Mechanics: Proe 29th US Symposium, Minneapolis, 13-15 June 1988 P495-502. Publ Rotterdam." A A Balkema, 1988 Modelling of interaction of high pressure fluids within stressed rock masses is important to understanding permeability enhancement for geothermal reservoirs and similar situations. Current models are outlined,current understanding is discussed, and immediate and long term improvements are considered, all within limits imposed by the complex environment of a stressed rock mass. Conclusions indicate that interactive models must currently be limited to simple joint geometries in three dimensions.
Time dependent behaviour See also." 893247, 893427 893094 Pore shape evolution by solution transfer: thermodynamics and mechanics Reuschle, T; Trotignon, L; Gueguen, Y Geophys J V95, N3, Dec 1988, P535-547 Solution transfer creep is an important mechanism of deformation of the earth crust. Theoretical and laboratory simulations have not yet entirely clarified the process, as assumptions made may not be met by rock under natural stress. The deformation of a circular pore under constant biaxial stress and filled with a fluid under pressure is re-examined, concentrating on energy balance rather than kinetics. Results are used to simulate numerically the evolution of pore shape in the earth c rus t .
893091 Numerical analysis of multiple radial fracturing Christianson, bl C; Hart, R D; Schatz, J F Key Questions in Rock Mechanics: Proc 29th US Symposium, Minneapolis, 13-15 June 1988 P441-451. Publ Rotterdam: A A Balkema. 1988 Multiple radial fracturing due to explosive gas generation in low permeability gas bearing rocks has been modelled. The boundary element code G R I F F was used to model gas generation. Borehole pressurisation, fracture propagation, fracture curvature, gas flow, gas leakage, thermal quenching, and fracture arrest are simulated. Measurable material properties are input. Results are compared with field measurements, and indicate fractures curve less than assumed, and that conditions for long fracture propagation are difficult to maintain.
893095 Device for evaluating one-dimensional compressive loading rate effects Farr, J V; Woods, R D Geoteeh Test J VII, N4, Dec 1988, P269-275 An explosive-loaded uniaxial strain device, developed to measure loading rate effects for times to peak pressure ranging from a few minutes to less than a millisecond, is described. Results obtained from the new device and a conventional uniaxial strain cell for partially saturated carbonate sand show progressive stiffening of uniaxial strain response occurs as time to peak pressure decreases, and basic shape of the stress strain curve is maintained.
1989 Pergamon Press plc. Reproduction not permitted