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936127 Algorithm for transient pressure analysis in arbitrarily shaped reservoirs
348A possible. Increased and better quality data, practical applications of chemical kinetics to inhomogeneous systems, and advances in coupling flow and reaction modelling will further improve geochemical modelling. 90 refs 936120 Propagation of hyperalkaline cement pore waters into the geologic barrier surrounding a radioactive waste repository Eikenberg, J; Lichtner, P C Proc 7th International Symposium on Water-Rock Interaction, Park City, 13-18 July 1992 V1, P377-380. Publ Rotterdam: A A Balkema, 1992
A low to intermediate level waste repository in sedimentary host rocks in planned in Switzerland. Infiltration of groundwater in the near field of the structure could release a hyperalkaline plume into the surrounding rock. A coupled geothermal model (MPATH) is used to investigate alteration of the argillaceous rock under high pH environment and spread of the contaminant plume. Dissolution of quartz and clay minerals and precipitation of feldspars, zeolites, and cement-type phases are predicted. Two examples of alteration of the marl host are evaluated. 936121 Reaction of cement pore fluids with rock: implications for the migration of radionuclides Rochelle, C A; Bateman, K; Milodowski, A E; Noy, D J; Pearce, J; Savage, D; Hughes, C R Proc 7th International Symposium on Water-Rock Interaction, Park City, 13-18 July 1992 V1, P423-426. Publ Rotterdam." A A Balkema, 1992
Cementitious materials will be used extensively in deep disposal of low to intermediate level radioactive waste. In time, saturation with groundwater will occur and the alkaline pore fluid equilibrated with the concrete will advect into the host geology. Escaping radionuclides will migrate through a geosphere conditioned by reaction with the pore fluid. Reactions of common rock-forming minerals with such a pore fluid have been studied by computer modelling and laboratory experiments. Long term effects of the interaction on the ability of the host rock to retard migration of the radionuctides are evaluated.
Permeability and capillarity See also: 936029, 936030, 936275, 936431 936122 Shear-dependent fracture-zone transmissivity model Tannant, D D; Kaiser, P K Can Geotech J V30, NI, Feb 1993, P146-154
A simple flow model based on an en echelon structure for a fracture zone is presented and a phenomenological relation between shear displacement and transmissivity change established. Shear displacements around a circular opening are studied. The greatest shear-induced transmissivity changes occur when a continuous low transmissivity zone is created around the opening. High hydraulic gradients into the opening can then develop. The case of a discontinuous low transmissivity zone is also considered. An alternative mechanism to shearinduced dilation and normal stress-induced fracture closure for description of hydraulic response of fracture zones is provided.
936123 Effect of tunnel excavation on transmissivity distributions and flow in a fracture zone Tannant, D D; Kaiser, P K; Chan, D H Can Geotech J V30, N1, Feb 1993, P155-169
A decrease in fracture zone transmissivity was observed as a tunnel intersected the room 209 fracture zone in the URL. Decrease was greatest as pilot and slash faces proceeded past the fracture zone, and transmissivity recovered towards its original value as excavation progressed. The application of a shear dependent fracture zone transmissivity model developed by Tannant and Kaiser was better able to describe measured response than the conventional normal stress dependent fracture closure model. 936124 Reexamination of the permeability index of clays. Note Babu, G L S; Pandian, N S; Nagaraj, T S Can Geotech J V30, N1, Feb 1993, P187-191
The permeability index (slope of void ratio-coefficient of permeability relation) for sensitive clays can in general be related to 0.5 times the value of initial void ratio. The possibility of obtaining such a relation for Cochin marine clays in terms of liquid limit void ratio is indicated from analysis of published data using a generalised state parameter approach. In principle, these forms of equations for permeability index are tenable, even though they were obtained on the basis of experimental observations alone. 936125 Steam corefloods with concurrent X-ray CT imaging Cuthiell, D; Sedgewick, G; Kissel, G; Wooley, J Can Pet Technoi V32, N3, March 1993, P37-45
A series of laboratory steamflood simulations in sandpacks was carried out, with CT used to monitor online saturation data. Numerical simulation and history matching were used to infer steam relative permeability from the experimental data. Unexpectedly large variations in water saturation transverse to the steam propagation direction were found. These were explained by taking into account small core packing variations, not obvious in CT images, but detected in petrographic image analysis. 936126 Reservoir simulation integrated with geomechanics Tortike, W S; Farouq Ali, S M Can Pet Technoi V32, N5, May 1993, P28-37
In petroleum reservoir simulation it is often necessary to couple fluid flow and heat transfer with the geomechanical behaviour of the reservoir rocks. The assumption of linear elasticity is not adequate. A general coupled reservoir geomechanics model for thermal reservoir modelling is presented. Stress and fuid pressure response to cyclic injection of steam into tar sand, an elastoplastic material, is examined for the coupled and uncoupled cases. Differences are discussed. Changes in porosity obtained with this method are significantly different from those obtained assuming only linear elastic pore compressibility. 936127 Algorithm for transient pressure analysis in arbitrarily shaped reservoirs Yeung, K; Chakrabarty, C Comput Geosci V19, N3, March 1993, P391-397
In many practical situations, reservoir drainage shape is too complicated to be approximated by a circular or rectangular shaped system and relatively simple pressure transient analyses
© 1993 Pergamon Press Ltd. Reproduction not permitted
349A are inaccurate. Kuo (1990) provided a solution based on superposition in time for irregularly shaped reservoirs, but this is computationally intensive. A new fast algorithm is presented which avoids repeated evaluation of the exponential integral function by taking its derivative, and allows pressure transient analysis on a PC. The algorithm is described in detail and its source code illustrated in the program MATLAB. 936128 Study of massive water injection by thermoporomeehanical coupling model Shao, J F; Henry, J P; Skoezylaz, F; Shahrour, I Comput Geoteeh V15, N2, 1993, P105-121 Waterflooding of a petroleum reservoir is modelled. The basic equations of solid-fluid coupling in porous media are presented and a finite element model developed using a complete coupling algorithm. Thermal convection is taken into account. High flow rate and large temperature variations during injection can be handled. Pore pressure, temperature, and matrix compaction are evaluated as functions of injection time. The importance of the different terms of thermoporomechanical coupling is investigated to discover which can be eliminated without loss of accuracy if semi-coupled modelling is used. 936129 Examination of the Guelph permeameter for measuring the soil's hydraulic properties Salverda, A P; Dane, J H Geoderma V57, N4, June 1993, P405-421 The Guelph permeameter method (GPM) is a convenient field technique for measurement of hydraulic properties of unsaturated soils, but some negative values of hydraulic conductivity and matrix flux potential from the GPM have been reported, especially in heterogeneous soils. The GPM has therefore been systematically evaluated over a wide range of soil types and conditions. Data handling techniques to eliminate the negative parameters are discussed. 936130 Recharge of a backfilled excavation: an examination of field behaviour. Technical note Thomas, H R; King, S D Geotechnique V43, N2, June 1993, P325-329 A comparison is presented of field behaviour and finite element simulation of infiltration of a trench in Kimmeridge clay backfilled with crushed limestone and capped with the clay. Volumetric moisture contents were measured at several depths using a neutron probe. Modelling used laboratory values of hydraulic parameters and rainfall data interpreted as two sets of boundary conditions, wet days and dry/intermediate days. Good correlation was found between measured and predicted moisture content-time curves. 936131 Stress state-permeability relationships for fine-grained soils. Technical note Nagaraj, T S; Pandian, N S; Raju, P S R N Geotechnique V43, N2, June 1993, P333-336 Even use of the Kozeny-Carman equation, which takes into account void ratio and structure of the soil, cannot predict permeability of fine grained soils with acceptable accuracy for engineering purposes. Three natural clay soils and a bentonite have been examined in the laboratory and void ratio, liquid limit, compressibility, consolidation, and permeability eharacterised in the saturated normally consolidated state. Relations between compressibility and permeability are examined.
936132 Infiltration in soils with fractal permeability distribution Kemblowski, M W; Chang, C M Ground Water V31, N2, March-April 1993, P187-192 Some field data indicate that soil permeability distributions have a fractal character with long range correlation, rather than being a stationary, homogeneous stochastic process. Such a set of data from Berino, New Mexico, is analysed. The relation between the fractal character of hydraulic conductivity distribution and statistics of unsaturated flow is examined using Monte Carlo simulations. These results are compared to theoretical results obtained from spectral analysis of unsaturated flow.
936133 Transient and steady-state solute transport through a large unsaturated soil column Porro, I; Wierenga, P J Ground Water V31, N2, March-April 1993, P193-200 A large column experiment (0.95m diameter by 6m deep) was used to test whether solute transport parameters determined under steady state conditions can be used in transient, unsaturated flow and transport models and predictions without excessive loss of accuracy. Tracer pulses were followed through the column and transport parameters determined through optimization, using breakthrough curves observed at various depths. Tracer pulses lagged significantly behind moisture fronts, which indicates that parameters from these tests, used in a fully transient numerical model, will fairly describe transport under transient conditions.
936134 Uncertainty analyses of unsaturated zone travel time at Yucca Mountain Nichols, W E; Freshley, M D Ground Water V31, N2, March-April 1993, P293-301 The numerical code PORMC has been used to compute unsaturated zone travel time around the proposed repository at Yucca Mountain. An uncertainty analysis using the Monte Carlo method is then applied to estimate the relative importance of physical and hydrologic input variables. The parameters which should be the focus of future work on characterisation of the flow, including fast pathways, multidimensionality, and more than one geological unit, are identified.
936135 Effect of sand lenses on groundwater flow and contaminant migration San, K W E; Rowe, R K lnt J Num Anal Meth Geomeeh V17, N4, April 1993, P217241 Landfills are often located in areas with thick clay deposits to minimise potential for pollution of groundwater. The effect of homogeneous sand lenses in an otherwise homogeneous clay mass on fluid flow is examined by performing Monte Carlo simulations using a finite element flow model. Influences of percentage of sand lenses and their conductivity, localisation, average size, and nonuniformity of size are investigated. Volume of sand lens present has the most significant influence on fluid flow. The simple modelling technique used is seen to be of adequate accuracy for practical purposes.
© 1993 Pergamon Press Ltd. Reproduction not permitted
A low to intermediate level waste repository in sedimentary host rocks in planned in Switzerland. Infiltration of groundwater in the near field of the structure could release a hyperalkaline plume into the surrounding rock. A coupled geothermal model (MPATH) is used to investigate alteration of the argillaceous rock under high pH environment and spread of the contaminant plume. Dissolution of quartz and clay minerals and precipitation of feldspars, zeolites, and cement-type phases are predicted. Two examples of alteration of the marl host are evaluated. 936121 Reaction of cement pore fluids with rock: implications for the migration of radionuclides Rochelle, C A; Bateman, K; Milodowski, A E; Noy, D J; Pearce, J; Savage, D; Hughes, C R Proc 7th International Symposium on Water-Rock Interaction, Park City, 13-18 July 1992 V1, P423-426. Publ Rotterdam." A A Balkema, 1992
Cementitious materials will be used extensively in deep disposal of low to intermediate level radioactive waste. In time, saturation with groundwater will occur and the alkaline pore fluid equilibrated with the concrete will advect into the host geology. Escaping radionuclides will migrate through a geosphere conditioned by reaction with the pore fluid. Reactions of common rock-forming minerals with such a pore fluid have been studied by computer modelling and laboratory experiments. Long term effects of the interaction on the ability of the host rock to retard migration of the radionuctides are evaluated.
Permeability and capillarity See also: 936029, 936030, 936275, 936431 936122 Shear-dependent fracture-zone transmissivity model Tannant, D D; Kaiser, P K Can Geotech J V30, NI, Feb 1993, P146-154
A simple flow model based on an en echelon structure for a fracture zone is presented and a phenomenological relation between shear displacement and transmissivity change established. Shear displacements around a circular opening are studied. The greatest shear-induced transmissivity changes occur when a continuous low transmissivity zone is created around the opening. High hydraulic gradients into the opening can then develop. The case of a discontinuous low transmissivity zone is also considered. An alternative mechanism to shearinduced dilation and normal stress-induced fracture closure for description of hydraulic response of fracture zones is provided.
936123 Effect of tunnel excavation on transmissivity distributions and flow in a fracture zone Tannant, D D; Kaiser, P K; Chan, D H Can Geotech J V30, N1, Feb 1993, P155-169
A decrease in fracture zone transmissivity was observed as a tunnel intersected the room 209 fracture zone in the URL. Decrease was greatest as pilot and slash faces proceeded past the fracture zone, and transmissivity recovered towards its original value as excavation progressed. The application of a shear dependent fracture zone transmissivity model developed by Tannant and Kaiser was better able to describe measured response than the conventional normal stress dependent fracture closure model. 936124 Reexamination of the permeability index of clays. Note Babu, G L S; Pandian, N S; Nagaraj, T S Can Geotech J V30, N1, Feb 1993, P187-191
The permeability index (slope of void ratio-coefficient of permeability relation) for sensitive clays can in general be related to 0.5 times the value of initial void ratio. The possibility of obtaining such a relation for Cochin marine clays in terms of liquid limit void ratio is indicated from analysis of published data using a generalised state parameter approach. In principle, these forms of equations for permeability index are tenable, even though they were obtained on the basis of experimental observations alone. 936125 Steam corefloods with concurrent X-ray CT imaging Cuthiell, D; Sedgewick, G; Kissel, G; Wooley, J Can Pet Technoi V32, N3, March 1993, P37-45
A series of laboratory steamflood simulations in sandpacks was carried out, with CT used to monitor online saturation data. Numerical simulation and history matching were used to infer steam relative permeability from the experimental data. Unexpectedly large variations in water saturation transverse to the steam propagation direction were found. These were explained by taking into account small core packing variations, not obvious in CT images, but detected in petrographic image analysis. 936126 Reservoir simulation integrated with geomechanics Tortike, W S; Farouq Ali, S M Can Pet Technoi V32, N5, May 1993, P28-37
In petroleum reservoir simulation it is often necessary to couple fluid flow and heat transfer with the geomechanical behaviour of the reservoir rocks. The assumption of linear elasticity is not adequate. A general coupled reservoir geomechanics model for thermal reservoir modelling is presented. Stress and fuid pressure response to cyclic injection of steam into tar sand, an elastoplastic material, is examined for the coupled and uncoupled cases. Differences are discussed. Changes in porosity obtained with this method are significantly different from those obtained assuming only linear elastic pore compressibility. 936127 Algorithm for transient pressure analysis in arbitrarily shaped reservoirs Yeung, K; Chakrabarty, C Comput Geosci V19, N3, March 1993, P391-397
In many practical situations, reservoir drainage shape is too complicated to be approximated by a circular or rectangular shaped system and relatively simple pressure transient analyses
© 1993 Pergamon Press Ltd. Reproduction not permitted
349A are inaccurate. Kuo (1990) provided a solution based on superposition in time for irregularly shaped reservoirs, but this is computationally intensive. A new fast algorithm is presented which avoids repeated evaluation of the exponential integral function by taking its derivative, and allows pressure transient analysis on a PC. The algorithm is described in detail and its source code illustrated in the program MATLAB. 936128 Study of massive water injection by thermoporomeehanical coupling model Shao, J F; Henry, J P; Skoezylaz, F; Shahrour, I Comput Geoteeh V15, N2, 1993, P105-121 Waterflooding of a petroleum reservoir is modelled. The basic equations of solid-fluid coupling in porous media are presented and a finite element model developed using a complete coupling algorithm. Thermal convection is taken into account. High flow rate and large temperature variations during injection can be handled. Pore pressure, temperature, and matrix compaction are evaluated as functions of injection time. The importance of the different terms of thermoporomechanical coupling is investigated to discover which can be eliminated without loss of accuracy if semi-coupled modelling is used. 936129 Examination of the Guelph permeameter for measuring the soil's hydraulic properties Salverda, A P; Dane, J H Geoderma V57, N4, June 1993, P405-421 The Guelph permeameter method (GPM) is a convenient field technique for measurement of hydraulic properties of unsaturated soils, but some negative values of hydraulic conductivity and matrix flux potential from the GPM have been reported, especially in heterogeneous soils. The GPM has therefore been systematically evaluated over a wide range of soil types and conditions. Data handling techniques to eliminate the negative parameters are discussed. 936130 Recharge of a backfilled excavation: an examination of field behaviour. Technical note Thomas, H R; King, S D Geotechnique V43, N2, June 1993, P325-329 A comparison is presented of field behaviour and finite element simulation of infiltration of a trench in Kimmeridge clay backfilled with crushed limestone and capped with the clay. Volumetric moisture contents were measured at several depths using a neutron probe. Modelling used laboratory values of hydraulic parameters and rainfall data interpreted as two sets of boundary conditions, wet days and dry/intermediate days. Good correlation was found between measured and predicted moisture content-time curves. 936131 Stress state-permeability relationships for fine-grained soils. Technical note Nagaraj, T S; Pandian, N S; Raju, P S R N Geotechnique V43, N2, June 1993, P333-336 Even use of the Kozeny-Carman equation, which takes into account void ratio and structure of the soil, cannot predict permeability of fine grained soils with acceptable accuracy for engineering purposes. Three natural clay soils and a bentonite have been examined in the laboratory and void ratio, liquid limit, compressibility, consolidation, and permeability eharacterised in the saturated normally consolidated state. Relations between compressibility and permeability are examined.
936132 Infiltration in soils with fractal permeability distribution Kemblowski, M W; Chang, C M Ground Water V31, N2, March-April 1993, P187-192 Some field data indicate that soil permeability distributions have a fractal character with long range correlation, rather than being a stationary, homogeneous stochastic process. Such a set of data from Berino, New Mexico, is analysed. The relation between the fractal character of hydraulic conductivity distribution and statistics of unsaturated flow is examined using Monte Carlo simulations. These results are compared to theoretical results obtained from spectral analysis of unsaturated flow.
936133 Transient and steady-state solute transport through a large unsaturated soil column Porro, I; Wierenga, P J Ground Water V31, N2, March-April 1993, P193-200 A large column experiment (0.95m diameter by 6m deep) was used to test whether solute transport parameters determined under steady state conditions can be used in transient, unsaturated flow and transport models and predictions without excessive loss of accuracy. Tracer pulses were followed through the column and transport parameters determined through optimization, using breakthrough curves observed at various depths. Tracer pulses lagged significantly behind moisture fronts, which indicates that parameters from these tests, used in a fully transient numerical model, will fairly describe transport under transient conditions.
936134 Uncertainty analyses of unsaturated zone travel time at Yucca Mountain Nichols, W E; Freshley, M D Ground Water V31, N2, March-April 1993, P293-301 The numerical code PORMC has been used to compute unsaturated zone travel time around the proposed repository at Yucca Mountain. An uncertainty analysis using the Monte Carlo method is then applied to estimate the relative importance of physical and hydrologic input variables. The parameters which should be the focus of future work on characterisation of the flow, including fast pathways, multidimensionality, and more than one geological unit, are identified.
936135 Effect of sand lenses on groundwater flow and contaminant migration San, K W E; Rowe, R K lnt J Num Anal Meth Geomeeh V17, N4, April 1993, P217241 Landfills are often located in areas with thick clay deposits to minimise potential for pollution of groundwater. The effect of homogeneous sand lenses in an otherwise homogeneous clay mass on fluid flow is examined by performing Monte Carlo simulations using a finite element flow model. Influences of percentage of sand lenses and their conductivity, localisation, average size, and nonuniformity of size are investigated. Volume of sand lens present has the most significant influence on fluid flow. The simple modelling technique used is seen to be of adequate accuracy for practical purposes.
© 1993 Pergamon Press Ltd. Reproduction not permitted