Analysis of the power input needed to propagate multiple hydraulic fractures

Bunger, Andrew P.

doi:10.1016/j.ijsolstr.2013.01.004

Cited by 61 publications

(59 citation statements)

References 29 publications

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“…This new simulator features an implicit level set scheme to locate the propagating hydraulic fracture fronts that respond to their regimes of propagation and enables highly accurate simulations using a very coarse mesh, and the capability to dynamically partition the fluid among multiple, simultaneously growing hydraulic fractures in parallel, overlapping planes. Consistent with the predictions of Bunger (2013), these simulations demonstrate that two factors, substantial dissipation of energy through viscous fluid flow and effective containment of height growth, are critical to promoting simultaneous growth of multiple hydraulic fractures.…”

Section: Introductionsupporting

confidence: 73%

“…Germanovich et al 1997, Olson and Dahi-Taleghani 2009, Damjanac et al 2010, Cipolla et al 2011, Nagel et al 2011, Meyer and Bazan 2011, Kresse et al 2013, McClure and Horne 2013, a different and complimentary approach has recently been developed that uses simple analytical models to clarify the basic contributors to the energy balance of a system of multiple, simultaneously growing and parallel HFs (Bunger 2013). The analysis is built on the premise is that, given a well interval of a certain length with multiple entry points, the number of HFs that will actually grow corresponds to the number that minimizes the required energy input.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Simultaneous Growth of Multiple Interacting Hydraulic Fractures from Horizontal Wells

Bunger

Peirce

2014

Shale Energy Engineering 2014

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The technique of multistage hydraulic fracturing from horizontal wells is universally credited with enabling the economical production of hydrocarbon resources from shale formations. The method almost always entails the injection of fluid through the wellbore with the potential to create hydraulic fractures from multiple reservoir entry points, typically clusters of wellbore perforations, that are spaced out along the wellbore within a section that is colloquially referred to as a "stage". Arguably the most basic question about this situation is how many perforation clusters within a given fracturing stage can be expected to produce growing hydraulic fractures. This paper presents a numerical investigation of this issue that employs a newly-developed, fully coupled parallel planar 3D hydraulic fracturing simulator that features: implicit time stepping, an implicit level set scheme to locate the propagating hydraulic fracture fronts that respond to their regimes of propagation and enables highly accurate simulations using a very coarse mesh, and the capability to dynamically partition the fluid among multiple, simultaneously growing hydraulic fractures in parallel, overlapping planes. Our results demonstrate the dependence of the energetically preferred number of growing hydraulic fractures on the length of the isolated zone, the height of the reservoir, and the relative importance of the fluid viscosity. In particular, we show that reservoirs with effective height containment and injection strategies that ensure substantial viscous dissipation will promote growth of multiple simultaneous hydraulic fractures rather than localization to just one or two dominant fractures.

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Section: Introductionsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Simultaneous Growth of Multiple Interacting Hydraulic Fractures from Horizontal Wells

Bunger

Peirce

2014

Shale Energy Engineering 2014

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“…in the host rockU (i) , overcomes the work that is done on that dyke by the 290 stresses induced by the othersẆ be neglected for the present study (see Bunger (2013) for a more thorough 295 discussion).…”

mentioning

confidence: 92%

“…If mechanical models predict a natural spacing that tends to zero or 62 Lister, 1990; Adachi and Peirce, 2008). Here we examine the mechanical evi-88 dence for a natural, or optimal spacing within dyke swarms by extending the 89 method that has been previously developed by Bunger (2013) …”

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confidence: 99%

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Analytical predictions for a natural spacing within dyke swarms

Bunger

Menand

Cruden

et al. 2013

Earth and Planetary Science Letters

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Dykes often grow next to other dykes, evidenced by the widespread occurrence of dyke swarms that comprise many closely-spaced dykes. In giant dyke swarms, dykes are observed to maintain a finite spacing from their neighbors that is tens to hundreds of times smaller than their length. To date, mechanical models have not been able to clarify whether there exists an optimum, or natural spacing between the dykes. And yet, the existence of a natural spacing is at the heart of why dykes grow in swarms in the first place. Here we present and examine a mechanical model for the horizontal propagation of multiple, closely-spaced blade-like dykes in order to find energetically optimal dyke spacings associated with both constant pressure and constant * 710 Benedum Hall, 3700 O'Hara Street, Pittsburgh, PA, 15261, USA Email address: bunger@pitt.edu (Andrew P. Bunger) Preprint submitted to Earth and Planetary Science Letters May 9, 2013influx magma sources. We show that the constant pressure source leads to an optimal spacing that is equal to the height of the blade-like dykes. We also show that the constant influx source leads to two candidates for an optimal spacing, one which is expected to be around 0.3 times the dyke height and the other which is expected to be around 2.5 times the dyke height.Comparison with measurements from dyke swarms in Iceland and Canada lend initial support to our predictions, and we conclude that dyke swarms are indeed expected to have a natural spacing between first generation dykes and that this spacing scales with, and is on the order of, the height of the blade-like dykes that comprise the swarm.

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Mechanics of two interacting magma‐driven fractures: A numerical study

2014

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To understand magma focusing from broad melting zones in the crust, propagation in brittle rocks of two interacting dikes ascending from a single deep source has been modeled using a time-dependent plane strain hydraulic fracturing model. The source is assumed to generate a constant influx rate to feed the dike growth, which is also aided by buoyancy effects. In contrast to uncoupled model results, the simultaneous parallel growth of two dikes to a certain distance is found to occur provided that the two dikes are initially of different heights, which might be produced either by previous magma intrusion or during nucleation. The shorter dike will chase the longer one and they can either progressively merge or continue subparallel growth at a reduced spacing, depending on the deviator stress between the vertical and horizontal stresses and the initial lateral separation, with parameters given in dimensionless forms. Numerical results reveal the mechanics for simultaneous ascents of two subparallel dikes, in that dike interaction can produce a low-stress field, which is just above the tip of the shorter dike, favorable to growth of the shorter dike. The energy analysis indicates that the energy required for two subparallel dikes is less than that for a single dike during the late-time buoyancy-viscosity propagation stage where considerable ascent occurs. This growth behavior might provide the mechanism for simultaneous, instead of sequential, growth of various dikes in a single set.

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Analysis of the power input needed to propagate multiple hydraulic fractures

Cited by 61 publications

References 29 publications

Numerical Simulation of Simultaneous Growth of Multiple Interacting Hydraulic Fractures from Horizontal Wells

Numerical Simulation of Simultaneous Growth of Multiple Interacting Hydraulic Fractures from Horizontal Wells

Analytical predictions for a natural spacing within dyke swarms

Mechanics of two interacting magma‐driven fractures: A numerical study

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