Proppant

To carry proppant material into the fracture to create a conductive path for produced fluids... 

After the completion of the fracturing treatment, the fluid viscosity should decrease to allow the placement of the proppant and a rapid fluid return through the fracture. It is important to control the time at which the viscosity break occurs. In addition, the degraded polymer should produce little residue to restrict the flow of fluids through the fracture. 

To enhance fracture creation and proppant-carrying capability... 

Water-based polymers Thickener, to transport proppant reduces leak-off in formation... 

Intermediate- to high-strength ceramics Proppant material... 

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. 

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. 

Interactions Between Fracturing Fluid Additives and Enzyme Breakers. Despite their advantages over conventional oxidative breakers, enzyme breakers have limitations because of interferences and incompatibilities with other additives. Interactions between enzyme breakers and fracturing fluid additives including biocides, clay stabilizers, and certain types of resin-coated proppants have been reported [1455]. 

For worthwhile oil or gas well stimulation, the best proppant and fluids have to be combined with a good design plan and the right equipment. The selection of a proppant is an important factor in determining how successful the stimulation treatment can be. To select the best proppant for each well, a general understanding of available proppants is imperative. 

Sand is the simplest proppant material. Sand is cheap, but at higher stresses it shows a comparatively strong reduction in permeability. 

Fired ceramic spheroids have been described for use as a well proppant [1051], Each spheroid has a core made from raw materials comprising mineral particulates, silicium carbide, and a binder. The mixture includes a mineral with chemically bound water or sulfur, which blows the mixture during firing. Therefore the core has a number of closed air cells. Each spheroid has an outer shell surrounding the core, comprising a metal oxide selected from aluminum oxide and magnesium oxide. The fired ceramic spheroids have a fired density less than 2.2 g/cm. ... 

It is possible to build within the formation a porous pack that is a mixture of fibers and the proppant. The fibrous material may be any suitable material (e.g., natural or synthetic organic fibers, glass fibers, ceramic fibers, carbon fibers). 

The flowback of a proppant following fracture stimulation treatment is a major concern because of the damage to equipment and loss in well production. The mechanisms of flowback and the methods to control flowback have been recently discussed in the literature [ 1343]. To reduce proppant flow-back, a curable resin-coated proppant can be applied [1349]. The agent must be placed across the producing interval to prevent or reduce the proppant flowback. 

Thermoplastic Films. Recently, thermoplastic film [1342,1343] materials have been developed to reduce the proppant flowback that can occur after fracturing treatments. A heat-shrinkable film cut into thin slivers provides flowback reduction over broad temperature ranges and closure stress ranges... 

Adhesive-Coated Material. The addition of an adhesive-coated material [335] to proppants decreases the flowback of the particulates. Such adhesive-coated materials can be inorganic or organic fibers, flakes, and the like. The adhesive-coated material interacts mechanically with the proppant particles to prevent the flowback of particulates to the wellbore. The consolidation of a proppant also may occur via a polyurethane coating, which will slowly polymerize after the fracturing treatment because of a polyaddition process [1856]. 

M. D. Clark, P. L. Walker, K. L. Schreiner, and P. D. Nguyen. Methods of preventing well fracture proppant flow-back. Patent US 6116342, 2000. 

B. Dewprashad. Method of producing coated proppants compatible with oxidizing gel breakers. Patent US 5420174, 1995. 

P. D. Ellis and B. W. Surles. Chemically inert resin coated proppant system for control of proppant flowback in hydraulically fractured wells. Patent US 5604184,1997. 

J. J. Fitzgibbon. Use of uncalcined/partially calcined ingredients in the manufacture of sintered pellets useful for gas and oil well proppants. Patent US 4623630, 1986. 

J. J. Fitzgibbon. Sintered, spherical, composite pellets prepared from clay as a major ingredient useful for oil and gas well proppants. Patent CA 1232751, 1988. 

C. K. Johnson, K. T. Tse, and C. J. Korpics. Improved phenolic resin coated proppants with reduced hydraulic fluid interaction. Patent EP 542397, 1993. 

A. Khaund. Sintered low density gas and oil well proppants from a low cost unblended clay material of selected composition. Patent US 4668645,1987. 

A. K. Khaund. Improved stress-corrosion resistant proppant for oil and gas wells. Patent EP 207427,1987. 

P. R. Lemieux and D. S. Rumpf. Lightweight proppant for oil and gas wells and methods for making and using same. Patent AU 637575,... 

K. H. Nimerick, S. B. McConnell, and M. L. Samuelson. Compatibility of resin-coated proppants with crosslinked fracturing fluids. In Proceedings Volume, pages 245-250.65th Annu SPE Tech Conf (New Orleans, LA, 9/23-9/26), 1990. 

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