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Control of deformation intensity around a fault: natural and experimental examples
GEOMECHANICS ABSTRACTS
913004 Correlation of paleotectonic fracture and microfracture orientations in cores with seismic anisotropy at Cajon Pass drill hole, southern California Blenkinsop, T G J Geophys Res I:95, NB7, July 1990, P11143-11150
Geology Tectonic processes and structural geology See also: 913041. 913058 913001 Subsurface deformations in a layered elastic half-space Roth, F Geophys J V103, NI, Oct 1990, P147-155 A method has been developed, using the theory of dislocations, to calculate subsurface displacement, tilt, strain, and stress inside a layered half space due to sources such as strike slip or dip slip fault movement. Layers are assumed laterally homogeneous, but may vary in thickness. Displacement variation with depth is calculated, and results compared to those for an unlayered homogeneous half space. The analysis may be used to model deformation around underground sources or to trace information of the sources from observed movements. 913002 Axi-symmetric deformation of a thermo-poro-elastie halfspace: inflation of a magma chamber Bonafede, M Geophys J VI03, N2. Not, 1990, P289-299 Deformation observed at Phlegraean Fields, Italy, during 1982-1984 has been interpreted as resulting from migration of hot pressurised fluid to a shallow magma chamber. Elastic, poroelastic, and thermoelastic contributions are studied and seen to all make important contributions. The concave shape of the first stage of deformation can be reproduced by modelling linearly increasing fluid flow and/or temperature at the boundary of a spherical cavity. Gradual return to normal conditions (convex phase), then diffusive dissipation of excess pressure and heat follow. 913003 Formulation and application of element methods in the simulation of pressure and temperature history of geological basins Soreng, J Int J Num Anal Meth Geomech VI4. NS, Not, 1990. P525543 A mathematical model is presented to describe the compaction of sediments in geological basins. It provides a consistent and complete set of equations for compaction, pressure, and time histories. The pressure equation is discretised with respect to time directly from the principle of conservation of mass, the temperature equation using the principle of conservation of energy. These equations are integrated spatially to give time discretised element equations of pressure and temperature. The model has been successfully tested for some geological basins.
Fractures and microfractures in oriented cores from the deep drill hole show strong preferred orientation, with two major sets of extensive fractures and microfractures with vertical dips and northeast and northwest strikes. Regional tectonic history suggests that these fractures were probably formed before late Miocene-Pliocene. Observed seismic anisotropy is a result of these fractures, and not directly related to the modern San Andreas fault or formed by the in situ stress field. 913O05 Framework for constructing elastic reservoir simulation models Weber, K J; van Geuns, L C J Pet Technoi V42, NIO, Oct 1990. P1248-1253. 1296-1297 Practical methods of reservoir modelling are reviewed. General approaches are discussed and basic types of reservoir illustrated: layer cake, jigsaw puzzle, and labyrinth. A simple classification of sand-body architecture is proposed to help relate geology to fluid flow. The data structure obtained is generally quite predictable in terms of an understanding of typical sedimentary strata and stratigraphy of the facies studied. Methods to predict properties at reservoir scale from available borehole and outcrop information are examined. 913006 Depositionally and diagenetically controlled reservoir heterogeneity at Jordan field Major, R P; Holtz, M H J Pet Technoi V42. NIO. Oct 1990. P1304-1309 The Jordan field is in the Permian Basin of west Texas. About 37% of estimated reserves have been extracted and 24% still remain as mobile oil resources. A combined engineering and geological survey has been carried out to help optimise extraction strategy. Four flow units were delineated on the basis of depositional texture and diagenetic overprint. Highest production and storage capacity correspond to a region with permeability enhancing, carbonate leaching diagenetic alteration. Lowest production is from a diagenetically unaltered region in an updip position which has not been swept by waterflood. 913007 Control of deformation intensity around a fault:-natural and experimental examples Odonne, F J Struct Geol VI2, N7, 1990, P911-921 Experimental models of a wrench fault, comprising of a wax layer containing a precut plane, were deformed in uniaxial compression. Deformation intensity observed has been compared with that around the Meyruis fault, in Jurassic formations of the Causses massif, France, Similarity is seen between
1991 Pergamon Press pie. Reproduction not permitted 129A
913004 Correlation of paleotectonic fracture and microfracture orientations in cores with seismic anisotropy at Cajon Pass drill hole, southern California Blenkinsop, T G J Geophys Res I:95, NB7, July 1990, P11143-11150
Geology Tectonic processes and structural geology See also: 913041. 913058 913001 Subsurface deformations in a layered elastic half-space Roth, F Geophys J V103, NI, Oct 1990, P147-155 A method has been developed, using the theory of dislocations, to calculate subsurface displacement, tilt, strain, and stress inside a layered half space due to sources such as strike slip or dip slip fault movement. Layers are assumed laterally homogeneous, but may vary in thickness. Displacement variation with depth is calculated, and results compared to those for an unlayered homogeneous half space. The analysis may be used to model deformation around underground sources or to trace information of the sources from observed movements. 913002 Axi-symmetric deformation of a thermo-poro-elastie halfspace: inflation of a magma chamber Bonafede, M Geophys J VI03, N2. Not, 1990, P289-299 Deformation observed at Phlegraean Fields, Italy, during 1982-1984 has been interpreted as resulting from migration of hot pressurised fluid to a shallow magma chamber. Elastic, poroelastic, and thermoelastic contributions are studied and seen to all make important contributions. The concave shape of the first stage of deformation can be reproduced by modelling linearly increasing fluid flow and/or temperature at the boundary of a spherical cavity. Gradual return to normal conditions (convex phase), then diffusive dissipation of excess pressure and heat follow. 913003 Formulation and application of element methods in the simulation of pressure and temperature history of geological basins Soreng, J Int J Num Anal Meth Geomech VI4. NS, Not, 1990. P525543 A mathematical model is presented to describe the compaction of sediments in geological basins. It provides a consistent and complete set of equations for compaction, pressure, and time histories. The pressure equation is discretised with respect to time directly from the principle of conservation of mass, the temperature equation using the principle of conservation of energy. These equations are integrated spatially to give time discretised element equations of pressure and temperature. The model has been successfully tested for some geological basins.
Fractures and microfractures in oriented cores from the deep drill hole show strong preferred orientation, with two major sets of extensive fractures and microfractures with vertical dips and northeast and northwest strikes. Regional tectonic history suggests that these fractures were probably formed before late Miocene-Pliocene. Observed seismic anisotropy is a result of these fractures, and not directly related to the modern San Andreas fault or formed by the in situ stress field. 913O05 Framework for constructing elastic reservoir simulation models Weber, K J; van Geuns, L C J Pet Technoi V42, NIO, Oct 1990. P1248-1253. 1296-1297 Practical methods of reservoir modelling are reviewed. General approaches are discussed and basic types of reservoir illustrated: layer cake, jigsaw puzzle, and labyrinth. A simple classification of sand-body architecture is proposed to help relate geology to fluid flow. The data structure obtained is generally quite predictable in terms of an understanding of typical sedimentary strata and stratigraphy of the facies studied. Methods to predict properties at reservoir scale from available borehole and outcrop information are examined. 913006 Depositionally and diagenetically controlled reservoir heterogeneity at Jordan field Major, R P; Holtz, M H J Pet Technoi V42. NIO. Oct 1990. P1304-1309 The Jordan field is in the Permian Basin of west Texas. About 37% of estimated reserves have been extracted and 24% still remain as mobile oil resources. A combined engineering and geological survey has been carried out to help optimise extraction strategy. Four flow units were delineated on the basis of depositional texture and diagenetic overprint. Highest production and storage capacity correspond to a region with permeability enhancing, carbonate leaching diagenetic alteration. Lowest production is from a diagenetically unaltered region in an updip position which has not been swept by waterflood. 913007 Control of deformation intensity around a fault:-natural and experimental examples Odonne, F J Struct Geol VI2, N7, 1990, P911-921 Experimental models of a wrench fault, comprising of a wax layer containing a precut plane, were deformed in uniaxial compression. Deformation intensity observed has been compared with that around the Meyruis fault, in Jurassic formations of the Causses massif, France, Similarity is seen between
1991 Pergamon Press pie. Reproduction not permitted 129A