Permeability tensors for sedimentary structures

PROPERTIES:PERMEABILITY & CAPILLARITY is an important tool to assist with lithological identification and many associated applications. In most geologic settings, mixtures of different materials are quite common, and it is important to understand the effect of thin laminations on measured ( V / V ) ratios. An equation is derived for ( V / V ) in transvebsery-isotropic materials. It is found that evenrsmall amounts of a second component, such as 10% shale, can change ( V J V ) ratios significantly from that of a pure end member, sucPi as sandstone. Case studies will illustrate some practical applications. -Author 945070 A numerical and experimental study of the artificial freezing of sand G. Gioda, L. LocateUi & F. Gallavresi, Canadian Geotechnical Journal, 31 (1), 1994, pp 1-11. A study is presented of the transfer of heat within a saturated sand with reference to the analysis of artifical freezing of the ground. First, the main characteristics of the adopted finite element approach and of the technique that introduces the latent-heat effects during the water-tee phase transition are illustrated. Subsequently, the results of some laboratory freezing tests are presented. Finally, a parametric study is discussed that concerns the effects of pipe diameter, distance between pipes, and coolant temperature on the progress of the 0"C isotherm. -Authors

Permeability and capillarity 945071 Laboratory measurement of capillary pressure-saturation relationships in a rock fracture S. Reitsma & B. H. Kueper, Water Resources Research, 30(4), 1994, pp 865-878. A laboratory technique has been developed to measure the hysteretic relationshtp between capillary pressure and fluid saturation for a rough-walled rock fracture under different states of normal stress. The method is applied to a single, rough-walled fracture in limestone using oil and water as the nonwetting and wetting phase, respectively. The measured capillary pressure curves were found to be well represented by a Brooks-Corey porous media capillary pressure function. It was found that the inferred aperture distributions became less skewed with increased normal load. These aperture distributions were inferred using one of three conceptual models presented for nonwetting phase invasion of a rough-walled fracture under conditions of main drainage. -from Authors 945072 Effects of lithology and depth on the permeability of core samples from the Kola and KTB drill holes C. Morrow, D. Lockner, S. Hickman, M. Rusanov & T. Rockel, Journal of Geophysical Research, 99(B4), 1994, pp 7263:7274. Permeability measurements were conducted on intact core samples from the Kola drill hole in Russia and the KTB drill hole in Germany. The permeability of the basaltic samples was the lowest and most sensitive to pressure, ranging from 10-20 to 10-23m 2 as effective pressure increased from 5 to only 60 MPa. In contrast, the granodiorite gneiss samples were more permeable and less sensitive to pressure, with permeability values ranging from 10"17 to ][0"22 m z as effective pressures increased to 300 MPa. Amphibolites displayed intermediate behavior. There was an abundance o f microfraetures in the quartz-rich rocks, but a relative paucity of cracks in the marie rocks. -from Authors 945073 Permeability tensors for sedimentary structures G. E. Pickup, P. S. Ringrose, J. L. Jensen & K. S. Sorbic, Mathematical Geology, 26(2), 1994, pp 227-250. Several flow models for sandstones are investigated and their impact on the calculation of effective permeability for single phase flow is examined. Crossflow arises in some structures, in which case it may be necessary to use a tensor representation of the effective permeability. Conditions under which tensors are required are established e.g., in crossbedded structures with a high bedding angle, high permeability contrast, and laminae of comparable thick-

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ness. Cases where the off-diagonal terms can be neglected. -from Authors 945074 Air permeability from pneumatic tests in oxidized till K . B . Edwards & L. C. Jones, Journal of Environmental Engineering - ASCE, 120(2), 1994, pp 329-347. Soil vapor extraction (SVE) to remove volatile contaminants from contaminated soil in the unsaturated zone has been successful in sand and gravel formations. In less permeable glacial till, the usefulness of SVE is unclear. Field experiments in the loam till of central Iowa were performed to determine air permeabilities. A radial and vertical, anisotropic, heterogeneous compressible-flow model coupled with an optimization routine solved the inverse problem by using vacuum pressure and flow-rate data to estimate air permeabilities. Air-permeability anisotropy was determined to be less important than depth variations. -from Authors 945075 Determination of petrographic factors controlling permeability using petrographic image analysis and core data, Satun Field, Pattani Basin, Gulf of Thailand M. C. Bowers, R. Ehtlich & R. A. Clark, Marine & Petroleum Geology, 11(2), 1994, pp 148-156. Miocene sandstones of the Pattani Basin, Gulf of Thailand, undergo progressive diagenesis with depth. Permeability varies from the millidarcy to darcy range over the short depth interval of 6000-9000 ft (1828-2748 m) with a tendency for deeper samples to be less permeable. Image analysis of representative thin sections showed that these rocks contain five pore types, three of which are strongly related to permeability. Physical models of permeability allow the construction of 'artificial' rocks where the contributions to permeability of each pore type are calculated at various porosity values. -from Authors 945076 Diffusion through statically compacted clay C. L. He & M. A. A. Shebl, in: Hydrogeology, waste

disposal, science and politics. Prec. 30th symposium on engineering geology and geotechnical engineering, Idaho, 1994, ed P.K. Link, (Idaho State University), 1994, pp 461-474. A permeameter was built of non reactive materials to test samples compacted at different water contents and compaettve efforts. The flow of a permeating solute, Lie1, was monitored. Effluent samples were collected for solute concentration measurements. The concentrations were measured by performing atomic adsorption tests. At each compactive effort, permeability decreased as molding water content increased. Consequently, transit time (measured at relative concentration 50%) increased and diffusivity decreased. As compactive effort increased for soils compacted dry of optimum, permeability and diffusion decreased. On the other hand, as compactive effort increased for soils compacted wet of optimum, permeability and diffusivity increased. Tortuosity factor was indirectly measured from the diffusion and retardation rate. Tortuosity factor also decreased as placement water content was increased from dry of optimum to wet of optimum. These decreases were more pronounced for low compactive effort tests. -Authors 945077 Colloid transport in unsaturated porous media Jiamin Wan & J. L. Wilson, Water Resources Research, 30(4), 1994, pp 857-864. This paper explores the significance of the gas-water interface on colloid sorption and transport. Three types of common saturation conditions were simulated i n p a c k e d sand columns: 1) a completely water-saturated condition, 2) gas bubbles trapped by capillary forces as a nonwetting residual phase (15% gas), and 3) gaspresent as a continuous phase (46% gas), or in other words, a vadose zone situation. The retention of both hydrophilic and hydrophobic colloids increased with gas content of the porous medium. CoUoids preferentially sorbed onto thegas-water interface relative to the matrix surface. The degree of sorption increased with the increase of colloid surface hydrophobicity. These findings suggest an additional mechanism for