Temperature fracture permeability

R.A., Jr. "High Efficiency Fracturing Fluids for High-Temperature, Low-Permeability Reservoirs", SPE/DOE paper 11615, 1983 SPE/DOE Symposium on Low Permeability, Denver, March 14-16. 

Abstract We analyse the effect of thermal contraction of rock on fracture permeability. The analysis is carried out by using a 2D FEM code which can treat the coupled problem of fluid flow in fractures, elastic and thermal deformation of rock and heat transfer. In the analysis, we assume high-temperature rock with a uniformly-distributed fracture network. The rock is subjected to in-situ confining stresses. Under the conditions, low-temperature fluid is injected into the fracture network. Our results show that even under confining environment, the considerable increase in fracture permeability appears due to thermal deformation of rock, which is caused by the difference in temperature of rock and injected fluid. However, for the increase of fracture permeability, the temperature difference is necessary to be larger than a critical value, STc, which is given as a function of in-situ stresses, pore pressure and elastic properties of rock. 

Thus if the temperature difference AT becomes larger than AT, defined by Equation (8), the fracture permeability will increase drastically. AT, is referred to the critical temperature difference. Note that AT is independent of the size of the cooled region, i.e. d. 

Hydroxypropylguar gum gel can be crosslinked with borates [1227], ti-tanates, or zirconates. Borate-crosslinked fluids and linear hydroxyethyl-cellulose gels are the most commonly used fluids for high-permeability fracture treatments. This is for use for hydraulic fracturing fluid under high-temperature and high-shear stress. 

A methyl quatemized erucyl amine [660] is useful for aqueous viscoelastic surfactant-based fracturing fluids in high-temperature and high-permeability formations. 

McDaniel, B.W. "Realistic Fracture Conductivities of Proppants as a Function of Reservoir Temperature," SPE/DOE paper 16453, 1987 SPE/DOE Low Permeability Reservoirs Symposium, Denver, May 18-19. 

Infiltration of the permeable concrete with molten sulfur yields a matrix which is almost impermeable to water. The freeze-thaw durability tests have indicated this is so, and immersion tests showed that fully infiltrated specimens absorbed less than 0.3% water by volume over several months, although methanol immersion and vacuum poro-simeter measurements revealed that a pososity of over 5% was available for filling. A total shrinkage of about 13% (Table I) occurs when liquid sulfur crystallizes to the stable low-temperature S< form, but much of the volume change appears to be accommodated in closed pores and intercrystal inversion fractures which affect the permeability little. 

Plants exert additional effects on weathering. The presence of forest trees tends to lower soil surface temperatures by shading the soil surface and reducing surface albedo (Kelly et al., 1998). Also, roots fracture mineral grains and increase soil porosity and permeability, which allows greater contact between soil solutions and minerals (April and Keller, 1990 Colin et al., 1992). 

Long term rearrangement, i.e., after gel formation, can occur under some conditions. In first instance, it leads to straightening of strands of particles in the gel, which causes an increase in modulus, a weaker dependence of the modulus on particle concentration, and a decrease in fracture strain the fracture stress and the permeability are hardly affected. Stronger rearrangement does lead to an increase in permeability, and syneresis can readily occur. All these changes depend on gel type, formation temperature, storage temperature, pH, etc. 

Deterministic permeability models. Application of the above principles to high temperature stable isotopes was pioneered by Norton and Taylor (1979) in their models of isotopic alteration of the Skaergaard layered intrusion and its host rocks. They used discreet zones and layers to which they assigned individual permeability values. Cartwright (1997) presented two-dimensional cases in which he modeled individual high permeability networks (fractures). Cook et al. (1997) used multiple, constant permeability zones to model the distribution of lithologies in the Alta stock area (see detailed discussion below). The advantage of this approach is that the calculated stable isotope patterns can be compared directly with measured patterns provided the permeability structure is adequately known. Permeability is also a function of time. Bolton et al. 

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