Permeameter

About: Permeameter is a research topic. Over the lifetime, 926 publications have been published within this topic receiving 18438 citations.

Designs for disc permeameters

Abstract: Disc permeameters are designed to measure hydraulic properties of field soils containing macropores and preferential flow paths and are particularly useful in soil management studies. We present here designs for disc permeameters for both positive and negative water supply heads. The effects of the water supply membrane and soil contact material on permeameter performance are examined using approximate quasi-analytic solutions to the flow equation. This analysis provides approximate criteria for the selection of membrane and soil contact materials. Limitations to performance caused by restricted air entry are considered and design criteria are given also. We present in situ tests of the disc permeameter for the early stages of one-dimensional infiltration and an example of the deterministic variation of sorptivity of a field soil with supply potential. Finally, we use ponded and unsaturated sorptivities measured in situ with disc permeameters to find the saturated hydraulic conductivity and flow-weighted mean characteristic pore dimension of a field soil. View complete article To view this complete article, insert Disc 5 then click button8

Hydraulic and acoustic properties as a function of porosity in Fontainebleau Sandstone

Abstract: Laboratory measurements have been made of the permeability (k), free porosity (ϕL), compressional velocities (VP or VE), and compressional attenuations (QP or QE) in Fontainebleau sandstone over a continuous range of porosities ϕ from 3 to 28%. This large variation was achieved without any composition change: Fontainebleau sandstone is made of fine quartz grains with regular grain size (≈250 μm). Permeability was measured with a falling head permeameter. Velocities and attenuations were obtained either through an ultrasonic experiment for frequencies around 500 kHz or through a resonant bar technique experiment for frequencies around 5 kHz and in both cases with varying water saturation. The results show an excellent correlation between permeability k and total porosity ϕ for all our samples. For low porosities (ϕ = 3% to 9%), permeability (in millidarcies) is 2.75×10−5(ϕ)7.33, while for high porosities (ϕ = 9% to 28%), permeability k (in millidarcies) is given by 0.303(ϕ)3.05. The correlation is also excellent between free porosity and total porosity. On the other hand the correlation between acoustic properties and total porosity is not as clear as for hydraulic properties whatever the frequency (500 kHz or 5 kHz) or the water saturation. On the average, velocity decreases, and attenuation roughly increases with increasing total porosity. Velocity and attenuation values are related to the variation of grain contact structure, and two samples with the same porosity and permeability may exhibit different velocities and attenuations. The clear correlation between hydraulic properties and porosity is related to constant grain size, while the lack of correlation for acoustic properties emphasizes the importance of the microstructure.

Large-scale natural gradient tracer test in sand and gravel, Cape Cod, Massachusetts: 3. Hydraulic conductivity variability and calculated macrodispersivities

Abstract: Hydraulic conductivity (K) variability in a sand and gravel aquifer on Cape Cod, Massachusetts, was measured and subsequently used in stochastic transport theories to estimate macrodispersivities. Nearly 1500 K measurements were obtained by borehole flowmeter tests and permeameter analyses of cores. The geometric mean for the flowmeter tests (0.11 cm/s) is similar to that estimated from other field tests. The mean for the permeameter tests (0.035 cm/s) is significantly lower, possibly because of compaction of the cores. The variance for the flowmeter (0.24) is also greater than that for the permeameter (0.14). Geostatistical analyses applying negative exponential models with and without nuggets reveal similar spatial correlation structures for the two data sets. Estimated correlation scales range from 2.9 to 8 m in the horizontal and from 0.18 to 0.38 m in the vertical. Estimates of asymptotic longitudinal dispersivity (b.35–0.78 m) are similar in magnitude to that observed in the natural gradient tracer test (0.96 m) previously conducted at this site.

IN SITU MEASUREMENT OF FIELD-SATURATED HYDRAULIC CONDUCTIVITY, SORPTIVITY, AND THE α-PARAMETER USING THE GUELPH PERMEAMETER

Abstract: The Guelph permeameter method is used in 0.02-m- and 0.03-m-radius wells to measure in situ the field-saturated hydraulic conductivity (K10) and matric flux potential (φm) of a heterogeneous, anisotropic, structured loam soil. The K10, estimates, obtained using both Richards (GP-R) and Laplace (GP-L

Characterisation of Gas Transport Properties of the Opalinus Clay, a Potential Host Rock Formation for Radioactive Waste Disposal

Abstract: The Opalinus Clay in Northern Switzerland has been identified as a potential host rock formation for the disposal of radioactive waste. Comprehensive understanding of gas transport processes through this low-permeability formation forms a key issue in the assessment of repository performance. Field investigations and laboratory experiments suggest an intrinsic permeability of the Opalinus Clay in the order of 10-20 to 10-21 m2 and a moderate anisotropy ratio 25 nm. The determined entry pressures are in the range of 0.4-10 MPa and exhibit a marked dependence on intrinsic permeability. Both in situ gas tests and gas permeameter tests on drillcores demonstrate that gas transport through the rock is accompanied by porewater displacement, suggesting that classical flow concepts of immiscible displacement in porous media can be applied when the gas entry pressure (i.e. capillary threshold pressure) is less than the minimum principal stress acting within the rock. Essentially, the pore space accessible to gas flow is restricted to the network of connected macropores, which implies a very low degree of desaturation of the rock during the gas imbibition process. At elevated gas pressures (i.e. when gas pressure approaches the level of total stress that acts on the rock body), evidence was seen for dilatancy controlled gas transport mechanisms. Further field experiments were aimed at creating extended tensile fractures with high fracture transmissivity (hydro- or gasfracs). The test results lead to the conclusion that gas fracturing can be largely ruled out as a risk for post-closure repository performance.