- Email: [email protected]
Evaluation of opening and hydraulic conductivity of rock discontinuities
77A
Laboratory experiments were conducted to investigate the change in induced magnetisation caused by triaxlal stress variations in andeslte specimens. For constant confining pressures the axial load was first increased up to a given value and then decreased. Then, when the axial load was increased once more the induced axial nmgnetisation was found to decrease linearly with increase of axial load, while induced radial magnetisation increased linearly with increase of axial load. A tensori~l relationship between magnetic susceptibility variations and stress changes is proposed for small magnetic fields.
Permeability and capillarity 833~15 P}LRA'UKTRIC A N A L Y ~ S OF THE TRANSIENT METHOD OF ~'~iSURING PERMFABILITY Lin, W J Geophys Res, V87, NB2, i0 Feb 1962, PI055-
1060 Two approaches for the use of the transient method to determine the permeability of reservoir rocks are compared: the simplified methcd where the fluid storage in a rock sample is neglected and the pressure decay in the upstream reservoir is approximated by an exponential eunction of time, and the numerical version using the finite difference method. The numerical version is fourd to fit observed data very well and the permeability value calculated tends to be less than that from the simplified version. The difference between these two is found to depend on mar~ factors including rock properties, s~mple size and reservoir volumes. 833116 APPROACHEs TO EV~.LUATIN3 THE PERMEABILITY AND POROSITY OF FRACTURED ROCK ~<4SSES Doe, T W; Long~ J C S; Endo, H K Proc 23rd Symposium on Rock Mechanics, Berkeleyj 25-27 ~ugust 1982, F30-38. Publ New Yark: AIME,
1982 An aplrO~ch to treating flow through fractured rocks is presented which involves (i) determining statistical distributions for fracture area, density~ orientation, and aperture from field data s (2) computer generation of fracture systems from the statistical distributions, and (3) analysis of the permeability and porosity of the fracture systems. The fracture density and orientation data m~y come from core logging or mapping. The hydraulically a uproprlate apertures anl areas of the fractures come from transient flow analyses of single fracture well tests. These tests may also yield information on fracture defcanmability. Ana/ysis of flow through computer generated fracture systems shows that an equivalent porous medium permeability can be defined for some fracture systems if a l~mge number of fractures is taken into account. Auth.
8331~7 P E R ~ B I L I T Y ,
FERCOL~TION AhD STATISTICAL CRACK MECHANICS Dienes, J K Proc 23rd Symposium on Rock Mechanics, Berkeley, 25-27 August 1982, P86-9~. Publ New York: AIME,
1982 A theory of permeability in rock is developed which involves 3 factors: the average fluid flux per cr~ck, the number of cracks per unit area, and the fr~ction of cracks that are not isolated. Probabilistic theory is used together with the
hydrcdynamlc theory of flow through a single crack to develop an integral expression for permeability. The results have the form of Darcy's law for anisotropic media. 833118 EFFECTS OF FRACTURE TYPE (INDUCED VERSUS NATURAL) ON THE STRESS-FP~.CTURE C L O S U R E - F R A ~ PERMEABILITY RELATIONSHIPS Gale, J E Proc 23rd Symposium on Rock Mechanics, Berkeley~ 25-27 August 1982, F290-298. Publ New York: AIME, 1982 Seven 15cm diameter cores of gnelsslc granite, four containing induced fractures and three containing natural fractures all oriented normal to the core axis, were tested in an uniaxlal compression mode over a range of 0 to 30MPa. At given normal stress increments, over two or three loading and unloading cycles, the flow rates and changes in fracture aperture were measured. The induced fractures gave lower initial (at low stresses) and lower final flow rates (at maximum stress) than the natural fractures. Both types of fracture exhibited permanent fracture d~formation between loading cycles as well as highly nonlinear, with distinct hysteresis, loading and unloading flow rate-stress curves. A significant finding of this study is the breakdown of the cubic law for fracture flow in induced fractures subjected to ncrm~l stresses greater than 20MPa, with the breakdown occurring at much lower stresses in natural fractures. Auth.
833119 EVALUATION OF OPENING AND HYDRAULIC CONDUCTIVITY OF ROCK DISCONTINUITIES Cruz, P T; Quadros, E; CGrrea, D Proc 23rd 2ymposlum on Rock Mechanics, Berkeley, 25-27 August 1982, I~69-777. Publ New York: AIME, 1982 Describes a laboratory and field test programme to determine the hydraulic characteristics Of rock masses and discontinuities. Simple conductivlty tests on natural rock Joints were carried out in the laboratory and Ix-roping tests were carried out in the field. 833120 DL~TRIBUTION OF POROSITY IN COMPACTED CLAYS Bhasin, R N; Lcwell, C W Proc 10th International Conference on Soll Mechanics and Foundation Engineering, Stockholm, 15-19 June 1981 , V1, P563-566. Publ Rotterdam: A. A. Balkem~, 1981 Describes the measurement of the pore size distribution in compacted samples of a plastic kaolin and a silty clay, usirg the mercury intrusion method. For each soil a relatively fixed content of pares is present for smaller p~re sizes below 0.i micrometre, regardless of hew the soil is N~nipulated. These pares occur within individual grains or within clay clusters of roughly face to face oriented clay particles. The distribution of larger pores, lying between the grains and clay clusters, is del~ndent on moulding, water content and com~ective effort.
83312] L%~BOP~TORY FE~C.~ABILITY TEgTS WITH ANNULAR ~ A L s Hawley, J G; Northey, R D Proc 10th International Conference on soll Mechanics and Foundation Engineering, Stockholm, 15-19 June 1981, Vl, P617-620. Publ Rotterdam: A. i. Balkems, 1981 Laboratory hy~Iraulic permeability measurements are prone to large and unknown errors due to leakage at the boundary between soil and container.
Laboratory experiments were conducted to investigate the change in induced magnetisation caused by triaxlal stress variations in andeslte specimens. For constant confining pressures the axial load was first increased up to a given value and then decreased. Then, when the axial load was increased once more the induced axial nmgnetisation was found to decrease linearly with increase of axial load, while induced radial magnetisation increased linearly with increase of axial load. A tensori~l relationship between magnetic susceptibility variations and stress changes is proposed for small magnetic fields.
Permeability and capillarity 833~15 P}LRA'UKTRIC A N A L Y ~ S OF THE TRANSIENT METHOD OF ~'~iSURING PERMFABILITY Lin, W J Geophys Res, V87, NB2, i0 Feb 1962, PI055-
1060 Two approaches for the use of the transient method to determine the permeability of reservoir rocks are compared: the simplified methcd where the fluid storage in a rock sample is neglected and the pressure decay in the upstream reservoir is approximated by an exponential eunction of time, and the numerical version using the finite difference method. The numerical version is fourd to fit observed data very well and the permeability value calculated tends to be less than that from the simplified version. The difference between these two is found to depend on mar~ factors including rock properties, s~mple size and reservoir volumes. 833116 APPROACHEs TO EV~.LUATIN3 THE PERMEABILITY AND POROSITY OF FRACTURED ROCK ~<4SSES Doe, T W; Long~ J C S; Endo, H K Proc 23rd Symposium on Rock Mechanics, Berkeleyj 25-27 ~ugust 1982, F30-38. Publ New Yark: AIME,
1982 An aplrO~ch to treating flow through fractured rocks is presented which involves (i) determining statistical distributions for fracture area, density~ orientation, and aperture from field data s (2) computer generation of fracture systems from the statistical distributions, and (3) analysis of the permeability and porosity of the fracture systems. The fracture density and orientation data m~y come from core logging or mapping. The hydraulically a uproprlate apertures anl areas of the fractures come from transient flow analyses of single fracture well tests. These tests may also yield information on fracture defcanmability. Ana/ysis of flow through computer generated fracture systems shows that an equivalent porous medium permeability can be defined for some fracture systems if a l~mge number of fractures is taken into account. Auth.
8331~7 P E R ~ B I L I T Y ,
FERCOL~TION AhD STATISTICAL CRACK MECHANICS Dienes, J K Proc 23rd Symposium on Rock Mechanics, Berkeley, 25-27 August 1982, P86-9~. Publ New York: AIME,
1982 A theory of permeability in rock is developed which involves 3 factors: the average fluid flux per cr~ck, the number of cracks per unit area, and the fr~ction of cracks that are not isolated. Probabilistic theory is used together with the
hydrcdynamlc theory of flow through a single crack to develop an integral expression for permeability. The results have the form of Darcy's law for anisotropic media. 833118 EFFECTS OF FRACTURE TYPE (INDUCED VERSUS NATURAL) ON THE STRESS-FP~.CTURE C L O S U R E - F R A ~ PERMEABILITY RELATIONSHIPS Gale, J E Proc 23rd Symposium on Rock Mechanics, Berkeley~ 25-27 August 1982, F290-298. Publ New York: AIME, 1982 Seven 15cm diameter cores of gnelsslc granite, four containing induced fractures and three containing natural fractures all oriented normal to the core axis, were tested in an uniaxlal compression mode over a range of 0 to 30MPa. At given normal stress increments, over two or three loading and unloading cycles, the flow rates and changes in fracture aperture were measured. The induced fractures gave lower initial (at low stresses) and lower final flow rates (at maximum stress) than the natural fractures. Both types of fracture exhibited permanent fracture d~formation between loading cycles as well as highly nonlinear, with distinct hysteresis, loading and unloading flow rate-stress curves. A significant finding of this study is the breakdown of the cubic law for fracture flow in induced fractures subjected to ncrm~l stresses greater than 20MPa, with the breakdown occurring at much lower stresses in natural fractures. Auth.
833119 EVALUATION OF OPENING AND HYDRAULIC CONDUCTIVITY OF ROCK DISCONTINUITIES Cruz, P T; Quadros, E; CGrrea, D Proc 23rd 2ymposlum on Rock Mechanics, Berkeley, 25-27 August 1982, I~69-777. Publ New York: AIME, 1982 Describes a laboratory and field test programme to determine the hydraulic characteristics Of rock masses and discontinuities. Simple conductivlty tests on natural rock Joints were carried out in the laboratory and Ix-roping tests were carried out in the field. 833120 DL~TRIBUTION OF POROSITY IN COMPACTED CLAYS Bhasin, R N; Lcwell, C W Proc 10th International Conference on Soll Mechanics and Foundation Engineering, Stockholm, 15-19 June 1981 , V1, P563-566. Publ Rotterdam: A. A. Balkem~, 1981 Describes the measurement of the pore size distribution in compacted samples of a plastic kaolin and a silty clay, usirg the mercury intrusion method. For each soil a relatively fixed content of pares is present for smaller p~re sizes below 0.i micrometre, regardless of hew the soil is N~nipulated. These pares occur within individual grains or within clay clusters of roughly face to face oriented clay particles. The distribution of larger pores, lying between the grains and clay clusters, is del~ndent on moulding, water content and com~ective effort.
83312] L%~BOP~TORY FE~C.~ABILITY TEgTS WITH ANNULAR ~ A L s Hawley, J G; Northey, R D Proc 10th International Conference on soll Mechanics and Foundation Engineering, Stockholm, 15-19 June 1981, Vl, P617-620. Publ Rotterdam: A. i. Balkems, 1981 Laboratory hy~Iraulic permeability measurements are prone to large and unknown errors due to leakage at the boundary between soil and container.