Fracture conductivity

Borate-crosslinked fracturing fluids have been successfully used in fracturing operations. These fluids provide excellent rheologic, fluid loss, and fracture conductivity properties over fluid temperatures up to 105° C. The mechanism of borate crosslinking is an equilibrium process that can produce very high fluid viscosities under conditions of low shear [336]. 

Dewatering surfactants can be polyoxyethylene, polyoxypropylene, and polyethylene carbonates [1348] or p-tert-amylphenol condensed with formaldehyde, or they can be composed of a copolymer from 80% to 100% alkyl methacrylate monomers and hydrophilic monomers [777]. Such a well treatment fluid may be used in both fracturing and competition operations to enhance and maintain fracture conductivity over an extended period of production. 

The fracture must be wide enough to permit entry of proppant to a distance sufficient to stimulate production. Tons of proppant are normally required to fill this void. Therefore the fracturing fluid must suspend the proppant long enough for it to be transported and placed, by flow, throughout the fracture. To preserve the maximum accessible flow area, the proppant should be uniformly suspended inside the entire propped fracture area while the fracture closes. Kaspereit(15), as well as Smith(16), has made the point that fracture conductivity can be a limiting factor. If the... 

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. 

McDaniel, B.W. "Use of Wet Gas Flow for Long-Term Fracture Conductivity Measurements in the Presence of Gel Filter Cakes," SPE paper 17543, 1988 SPE Rocky Mountain Regional Meeting, Casper, May 11-13. 

ICim, C.M. and Losacano, J.A. "Fracture Conductivity Damage Due to Crosslinked Gel Residue and Closure Stress on Propped 20/40 Mesh Sand," 1985 SPE Annual Technical Conference and Exhibition, Las Vegas, September 22-25. 

Makurat, A., Barton, N. and Rad, N.S. 1990. Fracture conductivity variation due to normal and shear deformation. In Proe. Int. Symp. on Rock Fractures, Loen, Norway, pp. 535-540. 

Successful fradure acidizing treatments do not depend solely on good fluid-loss properties (30). Adequate fracture flow capadty must be established by the add system used. The quantity of rock removed and the pattern in which it is removed from the fracture face are important. Fracture flow capadty is dependent on the nature of the rock and the characteristics of the add, such as add type, volume, and concentration. Other factors that lead to increased fracture flow conductivity include foam quality and pumping rate. As long as the foam is stable, foamed add of any quality increases the fracture flow conductivity when compared with non-foamed adds. As well, increases in total treatment pumping rates achieve better fracture conductivities because of greater acidized fradure lengths. 

Zou, Yushi et al. 2012. Damage mechanism of coal powder on fracture conductivity. Journal of China Coal Society 37(11) 1890 1894. 

Foam fracturing fluid could improve sand ratio to ensure that fracturing fluid to carry proppant into the far-reaching cracks, thereby effectively increased the fracture conductivity. 

Fracture conductivity The capability of the fracture to conduct fluids under a given hydraulic head difference. 

Brannon, H. D., Ault, M. G. New Delayed Borate-Crosslinked Fluid Provides Improve Fracture Conductivity in High Temperature Applications 66th Annual Technical Conference and Exhibition of SPE, DaUas, Texas, October 6-9, 1991 (SPE 22838). 

With hydraulic fracturing, fracture conductivity is maintained by propping open a fracture created with a solid material, such as sand, bauxite, ceramic, and certain lighter-weight materials. When used in hydraulic fracturing, these materials are referred to as proppants. 

As mentioned in chapter 2, fracture acidizing is an alternative to hydraulic (propped) fracturing in carbonates. With fracture acidizing, fracture conductivity is achieved by using acid to etch the walls of the created fracture. With hydraulic fracturing, fracture conductivity is achieved by filling the fracture with solid proppant to hold it open. 

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