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Influence of increased effective stress on the permeability of chalks under hydrocarbon reservoir conditions
221A 914174 Three dimensional flow model in fractured rock mass Kobayashi, A; Yamashita, R Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P639-646. Publ Rotterdam: A A Balkema, 1990 A three dimensional finite element model for analysis of seepage in jointed rock masses is described. The fractures and faults which form the main paths for fluid flow are modelled by the discontinuum method, and the rock matrix (containing other small fractures) by the equivalent porous medium. The mesh generator which defines the closed block surrounded by randomly distributed fractures is first illustrated. Governing equations and finite element discretization are then presented, followed by some numerical results. 914175 Development and verification of a numerical technique for coupled hydromechanical phenomena in rocks Noorishad, J; Tsang, C F Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P673-679. Publ Rotterdam: A A Balkema, 1990 A development of the ROCMAS numerical method for hydromechanical analysis of fractured rocks is presented. ROCMAS II is partially verified against solutions from the literature, then fully verified using the original ROCMAS code, which uses a completely different solution procedure. ROCMAS 11 accommodates an incremental set up, strain softening and dilating shear, a hyperbolic normal closure joint model, and a new linearization scheme. It enables simulation of more realistic conditions including nonlinear rock behaviour. 914176 Influence of increased effective stress on the permeability of chalks under hydrocarbon reservoir conditions Leddra, M J; Jones, M E; Pederstad, K; Lonoy, A Proc International Chalk Symposium, Brighton, 4-7 September 1989 P253-260. Publ London: Thomas Telford. 1990 The determination of reservoir rock permeability is an important factor for the evaluation and simulation of reservoir potential. An experimental programme was designed to investigate the effects of dissipation of high pore fluid pressures, increase of the effective stresses, and compaction of reservoir rock on the permeability of the rock. Discussion of the reservoir geology, routine permeability analysis, and the evaluation of the risk of permeability decline due to compaction are presented.
Compressibility, swelling and consolidation See a~o: 914272, 914356, 914364, 914380 914177 Deformability and consolidation characteristics of soft Bangkok clay using screw plate tests Bergado, D T; Chong, K C; Daria, P A M; Alfaro, M C Can Geotech J V27, N5, Oct 1990. P531-545 Undrained and drained moduli and coefficient of consolidation (cv) were measured for soft Bangkok clay using screw plate tests and stress path controlled triaxial tests. Compressibility data were also obtained from conventional oedometer tests. The ratio of cv for the screw plate tests to that from the triaxial or oedometer tests compares favourably with field/laboratory test ratios in previous work. Pressure-settlement-time data from screw plate tests were similar to pressure-
deformation-time data from triaxial tests. Soil parameters from the screw plate data allowed reasonable prediction of test embankment settlement. 914178 Compressibility of cohesionless soils (In German) Anagnostopoulos, A G Geotechnik VI3, N4, 1990, P181-187 Settlement predictions for cohesionless soils are generally made on the basis of empirical formulae using SPT results or SPT derived compressibility. The conventional oedometer can also be used to measure compressibility. The relation between oedometer compressibility and effective stress, and factors affecting this relation have been examined for different soils. Empirical correlations are found for compressibility derived after reloading to in situ effective stress and SPT N count. Results from back analyses support these latter relations for sands. 914179 Simplified heave prediction model for expansive shale Dhowian, A W Geotech Test g VI3, N4, Dec 1990, P323-333 A prediction model for heave, based 0ns0il suction change, is presented, whose output is in good agreement with field measurements. This is further simplified to arrive at a model which uses water content variation to predict heave. Results are again accurate. The simplified model removes the need to' recover an undisturbed sample of rock, which may be highly weathered and friable as well as laminated, to obtain calibration data. 914180 Cryer's problem with large displacements and variable permeability. Technical note Gibson, R E; Gobert, A; Schiffman, R L Geotechnique V40, N4, Dec 1990. P627-631 Cryer (1963) undertook comparison of three dimensional consolidation analyses of Blot and Terzaghi for the case of a drained sphere of an ideal soil. Pore pressure rise in the centre of the soil mass above applied pressure is seen before dissipation (MandeI-Cryer effect). Extension to large strain and permeability dependent on consolidation is presented. Sudden and early drop in skeleton permeability close to the drainage surface with consolidation has a greater effect on rate of consolidation than does shortening of drainage path. Influence on the MandeI-Cryer effect is examined. 914181 lsostatic hot-pressing mechanism maps for pure and natural sodium chloride - applications to nuclear waste isolation in bedded and domal salt formations Zeuch, D H Int J Rock Mech Min Sci V27, N6, Dec 1990, P505-524 Mined WIPP salt is a candidate material for backfill around waste packages in repositories. It is expected to compact to form an effective seal in response to room closure. The isostatic hot pressing model of Helle et al (1985) is applied to pure NaCI and WIPP salt to develop predictive equations for density with time as a function of temperature and pressure. Calculations for NaCI indicate compaction is due to dislocation movement alone. The model is extended to dry WIPP salt. Predictions agree well with experimental data and indicate satisfactory performance under repository conditions. In situ moisture will increase the compaction rate.
© 1991 Pergamon Press pie. Reproduction not permitted
Compressibility, swelling and consolidation See a~o: 914272, 914356, 914364, 914380 914177 Deformability and consolidation characteristics of soft Bangkok clay using screw plate tests Bergado, D T; Chong, K C; Daria, P A M; Alfaro, M C Can Geotech J V27, N5, Oct 1990. P531-545 Undrained and drained moduli and coefficient of consolidation (cv) were measured for soft Bangkok clay using screw plate tests and stress path controlled triaxial tests. Compressibility data were also obtained from conventional oedometer tests. The ratio of cv for the screw plate tests to that from the triaxial or oedometer tests compares favourably with field/laboratory test ratios in previous work. Pressure-settlement-time data from screw plate tests were similar to pressure-
deformation-time data from triaxial tests. Soil parameters from the screw plate data allowed reasonable prediction of test embankment settlement. 914178 Compressibility of cohesionless soils (In German) Anagnostopoulos, A G Geotechnik VI3, N4, 1990, P181-187 Settlement predictions for cohesionless soils are generally made on the basis of empirical formulae using SPT results or SPT derived compressibility. The conventional oedometer can also be used to measure compressibility. The relation between oedometer compressibility and effective stress, and factors affecting this relation have been examined for different soils. Empirical correlations are found for compressibility derived after reloading to in situ effective stress and SPT N count. Results from back analyses support these latter relations for sands. 914179 Simplified heave prediction model for expansive shale Dhowian, A W Geotech Test g VI3, N4, Dec 1990, P323-333 A prediction model for heave, based 0ns0il suction change, is presented, whose output is in good agreement with field measurements. This is further simplified to arrive at a model which uses water content variation to predict heave. Results are again accurate. The simplified model removes the need to' recover an undisturbed sample of rock, which may be highly weathered and friable as well as laminated, to obtain calibration data. 914180 Cryer's problem with large displacements and variable permeability. Technical note Gibson, R E; Gobert, A; Schiffman, R L Geotechnique V40, N4, Dec 1990. P627-631 Cryer (1963) undertook comparison of three dimensional consolidation analyses of Blot and Terzaghi for the case of a drained sphere of an ideal soil. Pore pressure rise in the centre of the soil mass above applied pressure is seen before dissipation (MandeI-Cryer effect). Extension to large strain and permeability dependent on consolidation is presented. Sudden and early drop in skeleton permeability close to the drainage surface with consolidation has a greater effect on rate of consolidation than does shortening of drainage path. Influence on the MandeI-Cryer effect is examined. 914181 lsostatic hot-pressing mechanism maps for pure and natural sodium chloride - applications to nuclear waste isolation in bedded and domal salt formations Zeuch, D H Int J Rock Mech Min Sci V27, N6, Dec 1990, P505-524 Mined WIPP salt is a candidate material for backfill around waste packages in repositories. It is expected to compact to form an effective seal in response to room closure. The isostatic hot pressing model of Helle et al (1985) is applied to pure NaCI and WIPP salt to develop predictive equations for density with time as a function of temperature and pressure. Calculations for NaCI indicate compaction is due to dislocation movement alone. The model is extended to dry WIPP salt. Predictions agree well with experimental data and indicate satisfactory performance under repository conditions. In situ moisture will increase the compaction rate.
© 1991 Pergamon Press pie. Reproduction not permitted