Role of permeability and storage in the initiation and propagation of natural hydraulic fractures

Boutt, D. F.; Goodwin, Laurel B.; McPherson, Brian

doi:10.1029/2007wr006557

Cited by 12 publications

(9 citation statements)

References 38 publications

(59 reference statements)

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“…Model conditions are instantiated through this process much like the building of the rock itself. Grains are packed into an area, allowed to compact under load, and cements may be added under a state of stress 40, 53, 54. Various loading conditions can be applied to the numerical sample to model laboratory and field conditions.…”

Section: Modeling Sand Productionmentioning

confidence: 99%

A coupled fluid–solid model for problems in geomechanics: Application to sand production

Boutt

Cook

Williams

2011

Num Anal Meth Geomechanics

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SUMMARYSome of the most challenging problems in geomechanics involve the coupling between fluid flow and solid deformation. In this paper we briefly present an overview of existing coupling methods to problems involving fluid flow and deformation and describe testing of a new discrete-based coupling method for problems in porous media. Modeled permeability and porosity distributions are compared to idealized packed assemblies and results are presented for simulations of steady flow through porous media. Previously published results for the coupled model focused on few or multiple particles in a fluid, whereas our results show good agreement to packed assemblies of particles (i.e. porous media). Finally, the two-dimensional model is applied to sand production, a common problem in geomechanics. Sand production is defined as the co-production of both a fluid and solid phase in oil and gas wells. In our models, we capture initial sand production associated with early-time drawdown. Later-time results show episodic sanding rates associated with formation stability and instabilities. Both observations are qualitatively consistent with laboratory and field observations. We find that high confining pressure inhibits the production of sand, through elevated interparticle contact forces. It is argued that these physically based models have a use in testing and evaluating competing hypotheses of sand production but their applicability is currently limited to small spatial and temporal scales. We believe these models bridge an important gap between the underlying physics of micro-mechanical interactions of fluid and solid grains and the continuum descriptions of those systems.

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Section: Modeling Sand Productionmentioning

confidence: 99%

A coupled fluid–solid model for problems in geomechanics: Application to sand production

Boutt

Cook

Williams

2011

Num Anal Meth Geomechanics

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“…It includes a large variety of phenomena such as methane venting [1], hydraulic fractures [2][3][4], pockmarks [5][6][7], hydrothermal complexes [8,9], kimberlite pipes [10][11][12] or mud volcanoes [13][14][15][16]. Since the 90's, the technique of air sparging has also been developed.…”

Section: Introductionmentioning

confidence: 99%

Flow and fracture in water-saturated, unconstrained granular beds

et al. 2015

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The injection of gas in a liquid-saturated granular bed gives rise to a wide variety of invasion patterns. Many studies have focused on constrained porous media, in which the grains are fixed in the bed and only the interstitial fluid flows when the gas invades the system. With a free upper boundary, however, the grains can be entrained by the ascending gas or fluid motion, and the competition between the upward motion of grains and sedimentation leads to new patterns. We propose a brief review of the experimental investigation of the dynamics of air rising through a water-saturated, unconstrained granular bed, in both two and three dimensions. After describing the invasion pattern at short and long time, a tentative regime-diagram is proposed. We report original results showing a dependence of the fluidized zone shape, at long times, on the injection flow rate and grain size. A method based on image analysis makes it possible to detect not only the fluidized zone profile in the stationary regime, but also to follow the transient dynamics of its formation. Finally, we describe the degassing dynamics inside the fluidized zone, in the stationary regime. Depending on the experimental conditions, regular bubbling, continuous degassing, intermittent regime or even spontaneous flow-to-fracture transition are observed.

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“…Drained tests were not performed on Abo siltstone in our study. However, a similar sample of Abo siltstone was tested previously by Boutt et al [2009]. In that case, the drained test did not produce a fracture in either the bedding perpendicular or parallel cores, but the NHF test produced a fracture in the bedding perpendicular core.…”

Section: Resultsmentioning

confidence: 85%

“…Therefore, the primary difference between NHFs and induced hydraulic fractures is that propagation of NHFs is limited by the hydrologic properties of the rock. Because they have not been studied experimentally, the current understanding of NHF initiation and propagation is based on a large body of theoretical work and numerical modeling [ Secor , 1965; Rice and Cleary , 1976; Pollard and Holzhausen , 1979; Lacazette and Engelder , 1992; Renshaw and Harvey , 1994; Miller , 1995; Boutt et al , 2009]. Models for formation include continuum mechanics models of poroelastic deformation and linear elastic micro‐mechanical models.…”

Section: Introductionmentioning

confidence: 99%

Sample dilation and fracture in response to high pore fluid pressure and strain rate in quartz‐rich sandstone and siltstone

French¹,

Boutt²,

Goodwin³

2012

J. Geophys. Res.

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Natural hydraulic fractures (NHFs) are inferred to form where pore pressure exceeds the least compressive stress by an amount equal to the tensile strength of the rock. We improved upon an experimental protocol that meets the NHF criterion within cylindrical samples with the most tensile effective stress parallel to the sample axis. The effective tensile stresses achieved during these experiments ranged from 17–47 MPa. The pore fluids used had higher viscosities than water and the axial strain rate was rapid (∼10−3s−1) to delay dissipation of fluid pressure by flow. Four experiments on St. Peter Sandstone samples and two on an Abo Formation siltstone sample were performed under these conditions and under drained conditions. None of the drained experiments resulted in failure, but all of the sandstone and one of the siltstone samples fractured in response to elevated pore pressures. Consistent with field and theoretical studies, mechanical heterogeneity was a first order control on fracture location. In the absence of mesoscopic heterogeneity, fracture location coincided with the maximum pore pressure. Samples responded to elevated pore pressures and differential stresses by dilating, the magnitude of which was sufficient to achieve atmospheric pore pressure. Samples failed 2 to 250 s after experiencing the greatest pore pressures, when the effective stresses were no longer tensile. Thus, the high pore pressures and effective tensile stresses experienced early in the experiments were sufficient to fracture the rocks, even though they were not sustained until failure. These results provide insight into processes of fluid‐driven fracture formation.

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Role of permeability and storage in the initiation and propagation of natural hydraulic fractures

Cited by 12 publications

References 38 publications

A coupled fluid–solid model for problems in geomechanics: Application to sand production

A coupled fluid–solid model for problems in geomechanics: Application to sand production

Flow and fracture in water-saturated, unconstrained granular beds

Sample dilation and fracture in response to high pore fluid pressure and strain rate in quartz‐rich sandstone and siltstone

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