Permeability hydraulically created

Niitsuma, H., Detection of hydraulically created permeable structures in HDR/HWR reservoir by high-resolution seismic mapping techniques, this volume 2004... 

DETECTION OF HYDRAULICALLY CREATED PERMEABLE STRUCTURES IN HDR/HWR RESERVOIR BY HIGH RESOLUTION SEISMIC MAPPING TECHNIQUES... 

Niitsuma, H., Moriya, H., Asanuma, H., Evans, K., Jones, R., Jung, R. and Baria, R. (2002). Delecting hydraulically created permeable structures in the Soultz HDR site by high resolution seismic mapping techniques, Proc. of New Zealand Geothermal Workshop. 

Addition of rubber particles of 30% to 100% by weight to cement with a grain size of approximately 40 to 60 mesh (0.4 to 0.25 mm) will produce a lightweight cement. The addition of rubber particles also creates a low permeability. The compositions are advantageous for cementing zones subjected to extreme dynamic stresses such as perforation zones and the junctions of branches in a multi-sidetrack well. Recycled, expanded polystyrene lowers the density of a hydraulic cement formulation and is an environmentally friendly solution for downcycling waste materials. 

Hydraulic fracturing is a technique to stimulate the productivity of a well. A hydraulic fracture is a superimposed structure that remains undisturbed outside the fracture. Thus the effective permeability of a reservoir remains unchanged by this process. The increased productivity results from increased wellbore radius, because in the course of hydraulic fracturing, a large contact surface between the well and the reservoir is created. 

The formation of calcium carbonate (CaCOs), calcium sulfate, and barium sulfate scales in brine may create problems with permeability. Therefore it is advantageous that newly made fractures have a scale inhibitor in place in the fracture to help prevent the formation of scale. Formulations of hydraulic fracturing fluids containing a scale inhibitor have been described in the literature [1828]. 

Hydraulic conductivity is one of the characteristic properties of a soil relating to water flow. The movement of water in soil depends on the soil structure, in particular its porosity and pore size distribution. A soil containing more void space usually has a higher permeability. Most consolidated bedrocks are low in permeability. However, rock fractures could create a path for water movement. 

Comparing these airflow intervals with those permeable zones induced by conventional hydraulic fracturing indicated that explosive fracturing created additional communication paths to wells 2 and 5 at the 73-ft level. However, the injection capacity of well 3 was reduced 64%. This may have resulted from too wide a dispersion of the liquid explosive, so that the shot was not strong enough to lift and fracture the overburden rock permanently, or the fractures may have been plugged by fine oil-shale particles or mud. 

The through-flow zone has so far been described in a simplified mode, assuming all the hosting rocks are homogeneously permeable. Deviations from the simplified L-shape of the flow path are caused by the presence of hydraulic barriers, such as clay and shale, that may in certain places block the downflow and create local perched water systems and springs (Fig. 2.16) or cause steps in the path of the lateral flow zone. But the overall L-shape is generally preserved, as the water of perched systems finds pathways to resume the vertical downflow direction. 

The selection and preparation of sites for any of these gas stores is a fairly delicate process, because tightness can rarely be guaranteed on the basis of geological test drillings and modelling. The detailed properties of the cavity will not become fully disclosed until the installation is complete. The ability of the salt cavern to keep an elevated pressure may turn out not to live up to expectations. The stability of a natural rock cave, or of a fractured zone created by explosion or hydraulic methods, is also imcertain until actual full-scale pressure tests have been conducted. For the aquifers, the decisive measurements of permeability can only be made at a finite number of places, so surprises are possible due to rapid permeability change over small distances of displacement (Sorensen, 2004a). 

These concepts have been routinely employed to determine psds of genuine porous media [88]. A difficulty arises when they are applied to PEMs, since these membranes do not possess an intrinsic porosity. Instead, pores in them are created by the water of hydration, whereas in the dry state the pore network collapses. Gas permeability of PEM is very small. Thus, only with a certain degree of tolerance can one speak about three-phase capillary equilibria, implied in the Laplace equation. It is rather a semiempirical phenomenology, that allows one to relate the liquid pressure (the driving force of the hydraulic permeation)... 

The sample used in the laboratory permeability test had the same characteristics as the phosphogypsum in the piles. It was formed by settling a phosphogypsum slurry, followed by compaction, which is the same way the stockpiles are created. The permeability figure that resulted from the tests was the saturated hydraulic conductivity since the sample was completely immersed in a column of water during the test. However, phosphogypsum in the piles is not saturated with water but contains an average of about 15% moisture. Permeability decreases drastically with decreases in moisture content because of the loss of water head. The unsaturated hydraulic conductivity would be 10% or less of the saturated value I/O], or approximately 0.024 cm/h (2.0 m/year). 

Interstitial fluid pressures in normal tissues are approximately atmospheric or slightly sub-atmospheric, but pressures in tumors can exceed atmospheric by 10 to 30mmHg, increasing as the tumor grows. For 1-cm radius tumors, elevated interstitial pressures create an outward fluid flow of 0.1 fim/s [11]. Tumors experience high interstitial pressures because (i) they lack functional lymphatics, so that normal mechanisms for removal of interstitial fluid are not available, (ii) tumor vessels have increased permeability, and (iii) tumor cell proliferation within a confined volume leads to vascular collapse [12]. In both tissue-isolated and subcutaneous tumors, the interstitial pressure is nearly uniform in the center of the tumor and drops sharply at the tumor periphery [13]. Experimental data agree with mathematical models of pressure distribution within tumors, and indicate that two parameters are important determinants for interstitial pressure the effective vascular pressure, (defined in Section 6.2.1), and the hydraulic conductivity ratio, (also defined in Section 6.2.1) [14]. The pressure at the center of the tumor also increases with increasing tumor mass. 

Through observation of induced microseismic events and examination of well logging data, it has been understood that the permeable zone seems to be created by migration of shearing joints during hydraulic fracturing test, and that microseismic multiplets is considered to be seismic events associated with shearing of fractures which are favourably oriented to stress field. 

Mehta and Zydney [41] show a similar relationship exists for ultrafiltration membranes where transport through the membrane occurs by convective pore flow. A Robeson plot was created by taking the selectivity of an ultrafiltration membrane as the reciprocal of the protein sieving coefficient (the ratio of protein concentration in the permeate to that in the fluid adjacent to the membrane surface) and the permeability as the solvent hydraulic permeability. A plot of literature data for bovine serum albumin separation shows the existence of an upper bound. The location of the upper bound was predicted assuming the... 

The compressibility of cakes, i.e. the increasing resistance of cakes with pressure, can be tested in various ways. As was briefly mentioned in section 9.2.2, one way of testing the relationship a =/(Apc) is in the compression-permeability cell. The solids compression is created by the mechanical action of the piston—an obvious assumption made is that hydraulic pressime can be simulated by mechanical compression. 

Fractures are important for fluid flow in oil, gas, and water production and geothermal processes. In such cases, the fluids are stored mainly in the matrix porosity but produced primarily using fracture permeability. Fractures penetrating impermeable shale layers create hydraulic conductivity and can develop a reservoir. Artificial fracturing (hydrofrac) can create new fractures or magnify existing fracture. On the other hand, fractures significantly reduce mechanical rock properties. 

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