Approaching a universal scaling relationship between fracture stiffness and fluid flow

Pyrak‐Nolte, L. J.; Nolte, David D.

doi:10.1038/ncomms10663

Cited by 150 publications

(107 citation statements)

References 26 publications

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“…Figure 6a shows the fracture aperture size decreasing with an increase in confining pressure. Large-scale fractures are less affected by stress, while small-sized fractures are strongly affected by stresses37. The aperture tends to be constant as the confining pressure increases to 18.0 MPa.…”

Section: Resultsmentioning

confidence: 97%

Experimental investigation of the hydraulic and heat-transfer properties of artificially fractured granite

Luo

Zhu

Guo

et al. 2017

Sci Rep

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In this paper, the hydraulic and heat-transfer properties of two sets of artificially fractured granite samples are investigated. First, the morphological information is determined using 3D modelling technology. The area ratio is used to describe the roughness of the fracture surface. Second, the hydraulic properties of fractured granite are tested by exposing samples to different confining pressures and temperatures. The results show that the hydraulic properties of the fractures are affected mainly by the area ratio, with a larger area ratio producing a larger fracture aperture and higher hydraulic conductivity. Both the hydraulic apertureand the hydraulic conductivity decrease with an increase in the confining pressure. Furthermore, the fracture aperture decreases with increasing rock temperature, but the hydraulic conductivity increases owing to a reduction of the viscosity of the fluid flowing through. Finally, the heat-transfer efficiency of the samples under coupled hydro-thermal-mechanical conditions is analysed and discussed.

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Section: Resultsmentioning

confidence: 97%

Experimental investigation of the hydraulic and heat-transfer properties of artificially fractured granite

Luo

Zhu

Guo

et al. 2017

Sci Rep

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“…The state of stress influences the fluid flow in fractures through changing the void space between the two fracture surfaces in partial contact. Initial stress field and changes in stress regimes during CO 2 injection, therefore, affect the hydraulic and mechanical properties of the rock mass (Pyrak-Nolte and Nolte, 2016). While it is the size and spatial distribution of fracture apertures that control the volumetric flow rate and hydraulic properties, it is the asperities that define the mechanical properties of fractures (PyrakNolte and Nolte, 2016).…”

Section: Introductionmentioning

confidence: 99%

Effect of brine-CO₂ fracture flow on velocity and electrical resistivity of naturally fractured tight sandstones

et al. 2018

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Fracture networks inside geological CO 2 storage reservoirs can serve as primary fluid flow conduit, particularly in low-permeability formations. While some experiments focused on the geophysical properties of brine-and CO 2 -saturated rocks during matrix flow, geophysical monitoring of fracture flow when CO 2 displaces brine inside the fracture seems to be overlooked.We have conducted laboratory geophysical monitoring of fluid flow in a naturally fractured tight sandstone during brine and liquid CO 2 injection. For the experiment, the low-porosity, lowpermeability naturally fractured core sample from the Triassic De Geerdalen Formation was acquired from the Longyearbyen CO 2 storage pilot at Svalbard, Norway. Stress-dependence, hysteresis and the influence of fluid-rock interactions on fracture permeability were investigated.The results suggest that in addition to stress level and pore pressure, mobility and fluid type can affect fracture permeability during loading and unloading cycles. Moreover, the fluid-rock interaction may impact volumetric strain and consequently fracture permeability through swelling and dry out during water and CO 2 injection, respectively. Acoustic velocity and electrical resistivity were measured continuously in the axial direction and three radial levels.Geophysical monitoring of fracture flow revealed that the axial P-wave velocity and axial electrical resistivity are more sensitive to saturation change than the axial S-wave, radial P-wave, and radial resistivity measurements when CO 2 was displacing brine, and the matrix flow was negligible. The marginal decreases of acoustic velocity (maximum 1.6% for axial V p ) compared to 11% increase in axial electrical resistivity suggest that in the case of dominant fracture flow within the fractured tight reservoirs, the use of electrical resistivity methods have a clear advantage compared to seismic methods to monitor CO 2 plume. The knowledge learned from

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“…Fracture surface area loss under large effective stress has been observed in previous work [9,10]. The effect of contact area loss is often misinterpreted as the reduction of fracture permeability.…”

Section: Stress-dependent Fracture Permeability and Contact Surface Areamentioning

confidence: 90%

“…For example, Huo and Benson [9] reported a loss of contact area of opened fractures by scanning shale samples layer by layer. Later, Pyrak-Nolte and Nolte [10] conducted numerical simulations on fluid flow through porous media and the contact surface area was found to decrease with increasing effective stress as well. However, a mathematical model that represents the impact of contact surface area loss on shale gas production has not been investigated yet.…”

Section: Stress-dependent Matrix Permeabilitymentioning

confidence: 99%

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Impact of Stress-Dependent Matrix and Fracture Properties on Shale Gas Production

Tang

Zhang

et al. 2017

Energies

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Unconventional shale gas production is often characterized by a short period of high production followed by a rapid decline in the production rate. Given the high costs of hydraulic fracturing and horizontal drilling, it is critical to identify the mechanisms behind the production loss. The existing shale gas production models often assume constant matrix permeability. However, laboratory observations show that matrix permeability can decrease significantly with increasing effective stress, which highlights the necessity of considering the stress-dependent properties of shale matrix in production analysis. Moreover, the compaction of pore space will also increase the matrix permeability by enhancing the gas-slippage effect. In this paper, a matrix permeability model which couples the effect of pore volume compaction and non-Darcy slip flow is derived. Numerical simulations are conducted to understand the role of matrix permeability evolution during production. Changes of fractures' permeability and contact area during depletion process are also taken into account. The results indicate that the loss of fracture permeability has a greater impact at the early stage of the depletion process, while matrix permeability evolution is more important for the long-term production.

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Approaching a universal scaling relationship between fracture stiffness and fluid flow

Cited by 150 publications

References 26 publications

Experimental investigation of the hydraulic and heat-transfer properties of artificially fractured granite

Experimental investigation of the hydraulic and heat-transfer properties of artificially fractured granite

Effect of brine-CO₂ fracture flow on velocity and electrical resistivity of naturally fractured tight sandstones

Impact of Stress-Dependent Matrix and Fracture Properties on Shale Gas Production

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Approaching a universal scaling relationship between fracture stiffness and fluid flow

Cited by 150 publications

References 26 publications

Experimental investigation of the hydraulic and heat-transfer properties of artificially fractured granite

Experimental investigation of the hydraulic and heat-transfer properties of artificially fractured granite

Effect of brine-CO2 fracture flow on velocity and electrical resistivity of naturally fractured tight sandstones

Impact of Stress-Dependent Matrix and Fracture Properties on Shale Gas Production

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Product

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Effect of brine-CO₂ fracture flow on velocity and electrical resistivity of naturally fractured tight sandstones