Fracture Design

Stimulations are optimized to ensure that fracture development is confined to the target formation. 

Microseismic mapping technology is rooted in the observation that when a fracture is induced into a reservoir or the bounding rock layers the in situ stress is disturbed, resulting in shear failure and subsequent mini-earthquakes (Walser, 2010). 

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Kaspereit, D.H. "Fracture Design for Suspended Sand Packs" SPE paper 1843, 1979 SPE Annual Technical Conference and Exhibition, Las Vegas, September 23-26. 

Veatch, R.U., Jr. "Overview of Current Hydraulic Fracturing Design and Treatment Technology -... 

Hill, O.F., Ward, A.J., and Clement, C.C. "Austin Chalk Fracturing Design Using a Crosslinked Natural Polymer as a Diverting Agent," J. Pet. Technol.. 1978, 30(12), 1795 804. 

Harrington, L. and Hannah, R.R. "Fracturing Design Using Perfect Support Fluids for Selected Fracture Proppant Concentrations in Vertical Fractures," 1975 SPE Annual Meeting, Dallas, September 28 October 1. 

Nolte, K.G. "Fracture Design Considerations Based on Pressure Analysis," SPE paper 10911, 1982 SPE Cotton Valley Symposium, Tyler, May 20. See also Nolte, K.G. "Principles for Fracture Design Based on Pressure Analysis," SPE Prod. Eng.. February 1988, 22 30 Nolte, K.G. "Application of Fracture Design Based on Pressure Analysis," SPE Prod. Eng.. February 1988, SI-42. 

Nierode, D.E. "Comparison of Hydraulic Fracture Design Methods to Observed Field Results," SPE paper 12059, 1983 SPE Annual Technical Conference and Exhibition, San Francisco, October 5 8. 

Schlottnan, B.U., Miller, U.K., II and Lueders, R.K. "Massive Hydraulic Fracture Design for the East Texas Cotton Valley Sands," SPE paper 10133, 1981 SPE Annual Technical Conference and Exhibition of AIME, San Antonio, October 5-7. 

Evans, D.W. and Willis, K. "Fracture Execution An Essential Part of Every Fracture Design," paper No. 86-37 70, 1986 Annual Technical Meeting of the Petroleum Society of CIM, Calgary, June 8-11 -... 

Examples. To illustrate the use of fracture mechanics concepts, we will present several examples. Because these examples are intended to demonstrate the methods involved, they have been necessarily oversimplified the reader is cautioned against using them as exact patterns for actual fracture design and is referred to the references cited at the end of this chapter for additional details on practical problems. 

In the early days of fracturing treatments, proppant concentrations were 1-6 lb/gal, but now concentrations of 14 and 16 lb/gal are not uncommon. The effect of proppant on fluid viscosity (under laminar flow in the fracture) at low solid concentrations is not significant but is at higher solid concentrations. With recent advances in placement of high proppant concentrations and the desire to predict fracture geometry and extension accurately, it has become important to include the effect of proppant concentration on the viscosity of fracturing fluids in the currently available fracture design simulators. 

The magnitude and nature of the load are considered in formulating the design. The load may be essentially quasistatic, cycHc, or impact. Many stmctural failures, for example, have been caused by supposedly innocuous stmctural details welded in place without any consideration given to their effect on fatigue properties. The service temperatures are also important, since they affect the fracture resistance of a material. 

Injection Molding. Any standard design plunger or reciprocating screw injection machine can be used for PEA 340, although a reciprocating screw machine is preferred (32). Slow injection into mold cavities avoids surface or internal melt fracture, and control of ram speed is important at low... 

Sohd materials, such as gilsonite and asphalt, and partially soluble sulfonated asphalt may also be added to plug small fractures in exposed shale surfaces and thereby limit water entry into the formation (105,124). The asphalts are oxidized or treated to impart partial solubiUty. These materials may be softened by the downhole temperature, causing them to deform and squeeze into small openings exposed to the borehole. Laboratory tests designed to evaluate shale-stabilizing muds have confirmed the beneficial action of these materials (125) (see also Soil STABILIZATION). 

When the design temperatures are significantly below ambient temperature, the primary threat to tank integrity is failure of the material by britde fracture. The tank design codes usually provide thorough treatment of this topic to prevent catastrophic failure. Additionally, there is the consideration of corrosion allowance, defined as extra thickness added beyond that required for strength. Corrosion allowance is not discussed herein. 

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