- Email: [email protected]
Induced stresses in hydraulic fracturing operations
h6A
Properties of Rocks and Soils See also abstracts: h59,~91,505.
462 AKAI,K
ADACHI, T ANDO,N Existemce of a unique stress-straln-tlme relation of cl~s. SOILS FOUND .V15,NI, 1975, P1-16. The authors Iz~vestigate the existence of a gmaeral constitutive equation for clay, which describe its behaviour in terms of external loading conditions. They examine the results of four types of undrained triaxial compression test which were performed on fully saturated and normally consolidated clays. The results confirm the validity of earlier empirical relationships for constant strain rate behaviour and stress relaxation. Using these relationships the authors derive an empirical equation for creep and confirm the existence of a unique constitutive equation for the clay used in their experiments.
k63 MUELLER, L UNIV .KARLSRUHE, D Technical parameters of rock and rock masses .15F.2TR. INT.C~X~T.MECH.SCI.UDINE, ITALY,197h,COURSES & LECTURES NO .165, SPRING~-V~LAG, 1974, PI6- 34. Those engineering properties of the rock mass which require to be determined in engineering structures are examined. The author draws the distinction between studying rock material and rock masses, emphasizing the importance of discontinuities and their influence on rock mass properties. 464 JOHN, KW RUHR.UNIV .BOCHUM,D Engineerlng Properties of Jointed rock. 17F,17R. INT.C~NT.MECH.SCI .UDINE, ITALY,197~,COURSES & LECTURES NO .165,SPRING~-V~LAG, 1974, P172-186.
Texture, structure, composition and density See abstracts: 49B,Sh9.
Fracture processes k65 SHUCK, LZ U. S .BUR .MINES, MORGANTOWN, USA ADVANI, SH W.VIRGINIA UNIV. ,MORGANTOWN,USA Induced stresses in hydraulic fracturing operations.
&66 DANESHY, AA HALLIBURTON SERV., DUNCaN,OK, USA Three.dlmemalonal propagation of hydraulic fractures extandlng from open holes. 10F,IIR. APPLICATIONS OF ROCK MECHANICs,PROC.15TH ~ . R O C K MECH., SOUTH DAKOTA.ASCE, 1975, P157-179. An ~xperimmatal investigation is made on the shape of hydraulically induced fractures extending from a llne source. The fracture characteristics utilized in this study were the facial features; hackle marks; rib marks, and steps. The results indicate that hydraulic fractures extending from a line source propagate on a hyperbolic path, with their edge having an elliptical shape. The ma~or axis of the ellipses lies along the lirAe source, The treatment fluid flow inside the hydraulic fracture is also hyperbolic. The equations presented for the fracture opening show that the hydraulic fracture starts as a Grlffith crack and extends into a peraly-shaped fracture. 467 RLE~MEL, F RUHR. UNIV .BOCHUM, D A review of fracture criteria of brittle rock. 8F,9R. INT.CE~.MECH.sCI .UDINE, ITALY,197h,COURSES & LECTURES NO. 165, SPR INGER.V~LAG, 197h, P72 -84.
~68 RU~, F RU~-UNIV .BOCHUM, D Brittle fracture of rocks. IOF,12R. INT. C ~ T .MECH. SC I .UDINE, ITALY, 197h, COURSES & LECTURES NO. 165, SPR INGER-V~LAG, 1974, P86- 94. Some examples of typical laboratory fracture tests are presented and some field situations related to earthquake mechanisms are discussed.
Strength characteristics See also abstract: 485,
469 BRAND, EW Back pressure effects on the undrained strength characteristics of soft cl~v. SOILS FOUND.VIS, N2,1975, Pl-16. When undisturbed, saturated soil samples are removed from the ground, the pore water pressure in them drops, dissol. ved air is released from solution, and they become Unsaturated. The state of saturation ms~ be restored by applying a back pressure to the specimens in a triaxial compression cell. ~he author conducted a series of consolidated undrained triaxial tests to study the effects of different magnitudes of applied back pressure on the shear strength characteristics of a normally consolidated cls~. He found that the effects of back pressure were significant only for specim~as which were subjected to low consolidation pressures prior to shear, whilst those which were subjected to high consolidation pressures were virtually unaffected by the magnitude of the applied back pressUre.
1~,49R. APPLICATIONS OF ROCK MECHANICS,PROC.15TH ~ . R O C K MECH.,SOUTH DAEDTA. ASCE, 1975, P9B- 134. The objectives of this work are to develop a better understaud~nu of the mechanisms of the hydraulic fracturing process with emphasis placed upon stress analysis. A state-of-the-art discussion on the mechanics of the hydraulic fracturing process pertinent to stress analysis is presanted. Basic phases of the process are defined. Two-dimensional and three.dlmensional elasticity theory models are formulated and solved for the static field ~ud local stress distribution during initial fluid injection that occur during a fracture extension phase. Computations of fluid flow pressure-time resl~se affecting the stress distribution in a semi.infinite porous media ere given. Analytical results are compared with correspondlng experimentally-determlned v a l n e s from a laboratory model.
&70 ODA,M On stress-dilatancy relation of sand in simple shear test. SOILS FOUND.VI5, N2,1975, P17-29. The author proposes a stress-dilatancy relation for sand based on e~perimental studies of the stress-strain behaviour of samples sheared in a simple shear apparatUs. Tests show that as a first approximation sand may be considered a plastic material which undergoes anisotropic strain hardening and is composed of rigid cohesionless particles. Furthermore the principal aXes of stress and strain increment rotate gradually during monotonous increase of horizontal shear stress and they generally do not coincide. The author relates the stress ratio acting on the horizontal failure plane to the inclination of the major principal stress axis by a material constant. This
Properties of Rocks and Soils See also abstracts: h59,~91,505.
462 AKAI,K
ADACHI, T ANDO,N Existemce of a unique stress-straln-tlme relation of cl~s. SOILS FOUND .V15,NI, 1975, P1-16. The authors Iz~vestigate the existence of a gmaeral constitutive equation for clay, which describe its behaviour in terms of external loading conditions. They examine the results of four types of undrained triaxial compression test which were performed on fully saturated and normally consolidated clays. The results confirm the validity of earlier empirical relationships for constant strain rate behaviour and stress relaxation. Using these relationships the authors derive an empirical equation for creep and confirm the existence of a unique constitutive equation for the clay used in their experiments.
k63 MUELLER, L UNIV .KARLSRUHE, D Technical parameters of rock and rock masses .15F.2TR. INT.C~X~T.MECH.SCI.UDINE, ITALY,197h,COURSES & LECTURES NO .165, SPRING~-V~LAG, 1974, PI6- 34. Those engineering properties of the rock mass which require to be determined in engineering structures are examined. The author draws the distinction between studying rock material and rock masses, emphasizing the importance of discontinuities and their influence on rock mass properties. 464 JOHN, KW RUHR.UNIV .BOCHUM,D Engineerlng Properties of Jointed rock. 17F,17R. INT.C~NT.MECH.SCI .UDINE, ITALY,197~,COURSES & LECTURES NO .165,SPRING~-V~LAG, 1974, P172-186.
Texture, structure, composition and density See abstracts: 49B,Sh9.
Fracture processes k65 SHUCK, LZ U. S .BUR .MINES, MORGANTOWN, USA ADVANI, SH W.VIRGINIA UNIV. ,MORGANTOWN,USA Induced stresses in hydraulic fracturing operations.
&66 DANESHY, AA HALLIBURTON SERV., DUNCaN,OK, USA Three.dlmemalonal propagation of hydraulic fractures extandlng from open holes. 10F,IIR. APPLICATIONS OF ROCK MECHANICs,PROC.15TH ~ . R O C K MECH., SOUTH DAKOTA.ASCE, 1975, P157-179. An ~xperimmatal investigation is made on the shape of hydraulically induced fractures extending from a llne source. The fracture characteristics utilized in this study were the facial features; hackle marks; rib marks, and steps. The results indicate that hydraulic fractures extending from a line source propagate on a hyperbolic path, with their edge having an elliptical shape. The ma~or axis of the ellipses lies along the lirAe source, The treatment fluid flow inside the hydraulic fracture is also hyperbolic. The equations presented for the fracture opening show that the hydraulic fracture starts as a Grlffith crack and extends into a peraly-shaped fracture. 467 RLE~MEL, F RUHR. UNIV .BOCHUM, D A review of fracture criteria of brittle rock. 8F,9R. INT.CE~.MECH.sCI .UDINE, ITALY,197h,COURSES & LECTURES NO. 165, SPR INGER.V~LAG, 197h, P72 -84.
~68 RU~, F RU~-UNIV .BOCHUM, D Brittle fracture of rocks. IOF,12R. INT. C ~ T .MECH. SC I .UDINE, ITALY, 197h, COURSES & LECTURES NO. 165, SPR INGER-V~LAG, 1974, P86- 94. Some examples of typical laboratory fracture tests are presented and some field situations related to earthquake mechanisms are discussed.
Strength characteristics See also abstract: 485,
469 BRAND, EW Back pressure effects on the undrained strength characteristics of soft cl~v. SOILS FOUND.VIS, N2,1975, Pl-16. When undisturbed, saturated soil samples are removed from the ground, the pore water pressure in them drops, dissol. ved air is released from solution, and they become Unsaturated. The state of saturation ms~ be restored by applying a back pressure to the specimens in a triaxial compression cell. ~he author conducted a series of consolidated undrained triaxial tests to study the effects of different magnitudes of applied back pressure on the shear strength characteristics of a normally consolidated cls~. He found that the effects of back pressure were significant only for specim~as which were subjected to low consolidation pressures prior to shear, whilst those which were subjected to high consolidation pressures were virtually unaffected by the magnitude of the applied back pressUre.
1~,49R. APPLICATIONS OF ROCK MECHANICS,PROC.15TH ~ . R O C K MECH.,SOUTH DAEDTA. ASCE, 1975, P9B- 134. The objectives of this work are to develop a better understaud~nu of the mechanisms of the hydraulic fracturing process with emphasis placed upon stress analysis. A state-of-the-art discussion on the mechanics of the hydraulic fracturing process pertinent to stress analysis is presanted. Basic phases of the process are defined. Two-dimensional and three.dlmensional elasticity theory models are formulated and solved for the static field ~ud local stress distribution during initial fluid injection that occur during a fracture extension phase. Computations of fluid flow pressure-time resl~se affecting the stress distribution in a semi.infinite porous media ere given. Analytical results are compared with correspondlng experimentally-determlned v a l n e s from a laboratory model.
&70 ODA,M On stress-dilatancy relation of sand in simple shear test. SOILS FOUND.VI5, N2,1975, P17-29. The author proposes a stress-dilatancy relation for sand based on e~perimental studies of the stress-strain behaviour of samples sheared in a simple shear apparatUs. Tests show that as a first approximation sand may be considered a plastic material which undergoes anisotropic strain hardening and is composed of rigid cohesionless particles. Furthermore the principal aXes of stress and strain increment rotate gradually during monotonous increase of horizontal shear stress and they generally do not coincide. The author relates the stress ratio acting on the horizontal failure plane to the inclination of the major principal stress axis by a material constant. This