Fracturing-Pressure Analysis for Nonideal Behavior

Nolte, K.G.

doi:10.2118/20704-pa

Cited by 111 publications

(29 citation statements)

References 12 publications

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“…The fluid flow could be laminar, turbulent, or Darcy flow through proppant pack, and is described correspondingly by different laws. For the general case of 1D laminar flow of power-law fluid in any given fracture branch obeys the Poiseuille law (Nolte, 1991) 1 '…”

Section: Ufm Model Descriptionmentioning

confidence: 99%

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Modeling of Interaction of Hydraulic Fractures in Complex Fracture Networks

et al. 2012

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A recently developed unconventional fracture model (UFM) is able to simulate complex fracture network propagation in a formation with pre-existing natural fractures. Multiple fracture branches can propagate simultaneously and intersect/cross each other. Each open fracture exerts additional stresses on the surrounding rock and adjacent fractures, which is often referred to as "stress shadow" effect. The stress shadow can cause significant restriction of fracture width, leading to greater risk of proppant screenout. It can also alter the fracture propagation path and drastically affect fracture network patterns. It is hence critical to properly model the fracture interaction in a complex fracture model.A method for computing the stress shadow in a complex hydraulic fracture network is presented. The method is based on an enhanced 2D Displacement Discontinuity Method with correction for finite fracture height. The computed stress field is compared to 3D numerical simulation in a few simple examples and shows the method provides a good approximation for the 3D fracture problem. This stress shadow calculation is incorporated in the UFM. The results for simple cases of two fractures shows the fractures can either attract or repel each other depending on their initial relative positions and compares favorably with an independent 2D non-planar hydraulic fracture model. Additional examples of both planar and complex fractures propagating from multiple perforation clusters are presented, showing that fracture interaction controls the fracture dimension and propagation pattern. In a formation with small stress anisotropy, fracture interaction can lead to dramatic divergence of the fractures as they tend to repel each other. However, even when stress anisotropy is large and fracture turning due to fracture interaction is limited, stress shadowing still has a trong effect on fracture width, which affects the injection rate distribution into multiple perforation clusters, and hence verall fracture network geometry and proppant placement. s o

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Section: Ufm Model Descriptionmentioning

confidence: 99%

“…Nolte (1991) derived this stress and takes it into account in the fissure opening pressure calculation in the analysis of pressure-dependent leakoff in fissured formation.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Interaction of Hydraulic Fractures in Complex Fracture Networks

et al. 2012

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“…The low-permeability shales should act as a fracture barrier to blunt upward fracture growth and prevent vertical fluid communication. Whether the low-permeability formation adjacent to the injection zone will act as a fracture barrier is strongly dependent on the stress contrast between the layers (Nolte 1991). During a slurry injection, the carrying fluid bleeds off rapidly, leaving behind solid waste within the fracture.…”

Section: Deep Well Injection Of Solid Wastementioning

confidence: 99%

The role of hydromechanical coupling in fractured rock engineering

Rutqvist

Stephansson

2003

Hydrogeology Journal

577

332

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This paper provides a review of hydromechanical (HM) couplings in fractured rock, with special emphasis on HM interactions as a result of or directly connected with human activities. In the early 1960s, the coupling between hydraulic and mechanical processes in fractured rock started to receive wide attention. A series of events-including dam failures, landslides, and injection-induced earthquakes-were believed to result from HM interaction. Moreover, the advent of the computer technology in the 1970s made possible the integration of nonlinear processes such as stress-permeability coupling and rock mass failure into coupled HM analysis. Coupled HM analysis is currently being applied to many geological engineering practices. One key parameter in such analysis is a good estimate of the relationship between stress and permeability. Based on available laboratory and field data it was found that the permeability of fractured rock masses tends to be most sensitive to stress changes at shallow depth (low stress) and in areas of low in situ permeability. In highly permeable fractured rock sections, fluid flow may take place in clusters of connected fractures that are locked open as a result of previous shear dislocation or partial cementation of hard mineral filling. Such locked open fractures tend to be relatively insensitive to stress and may therefore be conductive at great depths.Because of out the great variability of HM properties in fractured rock, and the difficulties in using laboratory data for deriving in situ material properties, the HM properties of fractured rock masses are best characterized in situ.

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“…Nolte [17] derived an equation of this stress in the analysis of pressure-dependent leakoff in fissured formation.…”

Section: Interaction Between Parallel Fracturesmentioning

confidence: 99%