Hydraulic fracturing fluids

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. 

Naturally occurring polysaccharides and their derivatives form the predominant group of water-soluble species generally used as thickeners to impart viscosity to treating fluids [1092]. Other synthetic polymers and biopolymers have found ancillary applications. Polymers increase the viscosity of the fi ac-turing fluid in comparatively small amounts. The increase in fluid viscosity of hydraulic fracturing fluids serves for improved proppant placement and fluid loss control. Table 17 summarizes polymers suitable for fracturing fluids. 

Acrylics, A copolymer of 2-ethylhexylacrylate and acrylic acid is not soluble either in water or in hydrocarbons. The ester units are hydrophobic and the acid units are hydrophilic. An aqueous suspension with a particle size smaller than 10 p can be useful in preparing aqueous hydraulic fracturing fluids [776]. 

Relatively small quantities of a bacterial cellulose (0.60 to 1.8 g/liter) in hydraulic fracturing fluids enhance their rheologic properties [1425]. Proppant suspension is enhanced and friction loss through well casings is reduced. 

Fluid Loss Additives for Hydraulic Fracturing Fluids... 

A defoamer and an antifoamer composition are described for defoaming aqueous fluid systems [1908]. The composition of a typical defoamer for hydraulic fracturing fluids is shown in Table 17-9. 

A hydraulic fracturing fluid containing guar gum or other natural polymers can be stabilized against bacterial attack by adding heterocyclic sulfur... 

Figure 17-12. Biocides for hydraulic fracturing fluids 2-mercaptobenzoim-idazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercapto-thiazoline, 2,5-dimercapto-1,3,4-thiadiazole, and 2-imidazolidinethion.

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]. 

Buechley, T.C. and Lord, D.L. "Hydraulic Fracturing Fluid Mechanics State of the Art," Fluid Mechanics of Oil and Gas Production Symposium, 1973 National Meeting, A.I.Ch.E., New Orleans, March 11 15. 

Gall, B.L. and Raible, C.J. "The Use of Size Exclusion Chromatography to Study the Degradation of Water Soluble Polymers Used in Hydraulic Fracturing Fluids," Polvm. Mater. Sci. Eng. 1986, 55, 572 75, Anaheim. 

Raible, C.J. "Formation Damage Due to Hydraulic Fracturing Fluids," National Institute for Petroleum and Energy Research. Cooperative Agreement DE-FC01-83FE60149, October 1, 1983-September 30, 1988. 

Typical hydraulic fracturing fluid compositions have been described by several authors (1 ). The fluids may be aqueous or hydrocarbon base and may also contain energizing gases such as nitrogen or... 

---