Fractures transmissivity

Fig, XIV-12. Freeze-fracture transmission electron micrographs of a bicontinuous microemulsion consisting of 37.2% n-octane, 55.8% water, and the surfactant pentaethy-lene glycol dodecyl ether. In both cases 1 cm 2000 A (for purposes of microscopy, a system producing relatively coarse structures has been chosen), [(a) Courtesy of P. K. Vinson, W. G. Miller, L. E. Scriven, and H. T. Davis—see Ref. 110 (b) courtesy of R. Strey—see Ref. 111.]... 

Figure 11. Freeze-fracture transmission electron micrograph of the microemulsion...

Nordqvist, A.W., Y.W. Tsang, C.F. Tsang, B. Dverstorp, and J. Andersson. 1996. Effects of high variance of fracture transmissivity on transport and sorption at different scales in a discrete model for fractured rocks. J. Contamin. Hydrol. 22 39-66. 

Example 1 A study of effect of sU ess state on seepage conductivity of single natural rock fracture (MH) was conducted by one of authors of this paper. In Figure 2 the effect of normal stress on the permeability of rock joint in granite is shown. The original fracture transmissivity is reduced due to... 

Figure 3 presents the resulting relationship between fracture transmissivity and effective normal stress. This function represents a fracture whose initial aperture is 10 pm at an initial effective stress of 17 MPa, corresponding to the initial vertical effective stress across the horizontal fracture. 

Figure 3. Fracture transmissivity versus effective fracture stress derived for k,o = 56 GPa/m and V c = 65 Mm.

The normal closure/opening mechanism as shown in Figure 1(a) is relatively well understood. This mechanism causes a decrease/increase of fracture transmissivity with an increase/decrease of normal stress magnitude. This mechanism plays a dominant role in fluid permeability of fractured rocks when failure does not occur in the fracture and deformation is not close to residual state. 

In our approach a detailed hydraulic analysis is carried out, where the flow and transport properties at the small scale are analysed by means of the fracture network software FracMan, Derschowitz et al. (1998), and MAFIC, Miller et al. (1999), that handle complex fracture geometries and fracture transmissivity distributions. The approach is probabilistic. A large number of network... 

The obtained fracture normal stresses, a (MPa), were related to hydraulic apertures, b (pm), using an approximate empirical relationship based on the laboratory loading-unloading tests of core data in Equation 1. These hydraulic apertures, at 100 years of heating, were in turn related to fracture transmissivity, using the cubic law , and compared to the original, in-situ, fracture transmissivity. 

The M effects of repository excavation and swelling of back filling material proved to be small. Our results focus on TM effects at 100 years of repository heating in the lower formation, as described in section 3.6. The changes in fracture transmissivity as a function of radial distance from the repository centre, r, are shown in Figure 4. 

Figure 4. Fracture transmissivity change due to 100 years of healing, for repository distance divided into 7.5 m intervals.

A distortion can be seen at r = 70 m, which is caused by two fractures, partly inside tbe fault zone. The most interesting locations for further study was decided to be at r = 15 m, where transmissivity is reduced by a factor 2, and at r = 180 m, where sub-vertical fracture transmissivity is slightly decreased, while sub-horizontal fractures show a slight increase. 

The effective conductivity seems to follow the overall fracture transmissivity reduction. Figure 7 shows changes in effective conductivity, average fracture transmissivity change (disregarding orientations for fracture sets) and a fitted trend. 

Figure 6.3 (a) Schematic diagram of shadowing-, (b) freeze-fracture transmission electron micrograph of ice cream showing fat droplets (F) and casein micelles (C) in the matrix (M)... 

The final evidence for the formation of an Abrikosov flux lattice of screw dislocations in liquid crystals was achieved by Zasadzinski et al. [39] via the visualization of the screw dislocations of (R)- and (S-)l-methylheptyl 4 -(4-n-tetradecyloxyphenylpropioloyloxy)-biphenyl-4-carboxylates using freeze-fracture transmission electron microscopy. Freeze-fracture transmission microscopy (TEM) is an essential tool for visualizing the TGBA phase at sufficient resolution in order to resolve the molecular organization. 

D. Observation of AOT Reversed Micelles Using Freeze-Fracture Transmission Eiectron Microscopy and Cryotransmission Electron Microscopy... 

Reversed micelles have very highly dynamic structures and are in rapid equilibrium with surfactant monomers. Therefore, it is usually difficult to observe their real features by microscopy. A freeze-fracture transmission electron microscope (TEM) would probably show the real picture of a reversed micellar solution because a freeze-fracture film of the reversed micelles is made by rapid cooling to — 150°C to stop instantly the dynamic nature of the structure. Figure 2(a) shows an electron micrograph of the AOT reversed micellar solution (5% w/v AOT-iso-octane solution, IV = 1) [44]. The visual observation by a... 

FIG. 2 Freeze-fracture transmission electron micrographs of AOT reversed micelles. (From Ref. 44.)... 

Figure 14.9 Freeze-fracture transmission electron micrograph images of a latex film prepared at 36°C from a surfrtctant-free PBMA latex (

A polyethyleneoxide-Z)-polydimethylsiloxane-polyethyleneoxide surfactant, (EO)i5-(DMS)i5-(EO)i5, was studied with freeze-fracture transmission electron microscopy and pulsed-field gradient nuclear magnetic resonance speetroseopy, in order to establish the effeet of glyeerol on the permeability of vesiele membranes. Small vesicles with diameters of less than 25 run and multilamellar vesicles with diameters larger than 250 nm were observed in pure water, which were modified when water was gradually replaced with glycerol [47]. 

It will be appreciated that visualization of the structure of liquid crystalline materials is a particularly difficult task as the phase being studied has liquid-like character. The technique of freeze fracture transmission electron microscopy allows examination of most systems however, lyotropic materials which contain greater than 85% water still prove to be difficult. The technique involves the fast freezing of the material and then examination of the fracture surface. Despite the obvious attraction of this method it appears to be still in its infancy. Studies of cholesteric, smectic " phases have been reported and show that it is possible to identify stacks of well-ordered materials which are often bananashaped but do conform to the concepts that have been developed above. 

To verify the accuracy of horizontal fracture transmissibility coefficient measured in the single slug test, the test result of slug test is usually compared to that of common pumping test result. Slug test uses pneumatic test mode, which is shown in Figure 6. 

From the analysis of test results, we can see that the horizontal fracture transmissibility coefficient can be figured out by the slug test, the accuracy of which is high. This lays a theoretical... 

It was proposed that the monomer/dopant salts form micelles which then serve as the soft-template for the formation of tubular structures. For the dopant-free or simplified method in which only aniline and ammonium persulfate are mixed, the initial formation of spherical micelles was observed by freeze-fracture transmission electron microscopy from which tubular structures were obtained. ... 

Dynamic light scattering (DLS) along with freeze-fracture transmission electron microscopy (FF-TEM) measurements revealed that the sizes of single microemnl-sion droplets vary with temperatme [19,20]. The role of the organic solvent was also investigated for this system changing cyclohexane by benzene, tolnene, or p-xylene [21-26]. 

FIGURE 2.3 Freeze-fracture transmission electron micrographs of a biocontinuous microemulsion consisting of (A) 37.2% n-octane, 55.8% water, and smfactant pentathylene glycol dodecyl ether (From Vinson, P.K., Sheehan, J.G., Miller, W.G., Scriven, L.E., and Davis, H.T., J. Phys. Chem., 95, 2546, 1991. With permission.) (B) 43.05% n-dodecane, 43.05% water and 13.9% didodecyl-methylammonium bromide. (From Jahn, W. and Strey, R., J. Phys. Chem., 92, 2294, 1988. With permission.) In both cases 1 cm = 2000 A. 

P.K. Vinson, J.G. Sheehan, W.G. Miller, L.E. Scriven, and H.T. Davis 1991 Viewing microemulsions with freeze-fracture transmission electron microscopy, J. Phys. Chem. 95, 2546-2550. 

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