Permeability enhancement through hydraulic fracturing: laboratory measurements combining a 3D printed jacket and pore fluid over-pressure

Gehne, Stephan; Benson, Philip

doi:10.1038/s41598-019-49093-1

Cited by 37 publications

(24 citation statements)

References 28 publications

(30 reference statements)

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“…The mechanical and P ‐wave anisotropy is 60% and 56%, respectively, as measured from indirect tensile strength tests and radial P ‐wave velocities (Gehne et al, ). It has a porosity of approximately ~6.5%, measured by helium pycnometery, and an intact permeability of approximately 10 −18 m 2 parallel to bedding and 10 −20 m 2 normal to bedding (Gehne & Benson, ), also measured using helium gas.…”

Section: Methodsmentioning

confidence: 99%

Fluid‐Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure

Gehne¹,

Inskip²,

Benson³

et al. 2020

JGR Solid Earth

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A number of key processes, both natural and anthropogenic, involve the fracture of rocks subjected to tensile stress, including vein growth and mineralization, and the extraction of hydrocarbons through hydraulic fracturing. In each case, the fundamental material property of mode‐I fracture toughness must be overcome in order for a tensile fracture to propagate. While measuring this parameter is relatively straightforward at ambient pressure, estimating fracture toughness of rocks at depth, where they experience confining pressure, is technically challenging. Here we report a new analysis that combines results from thick‐walled cylinder burst tests with quantitative acoustic emission to estimate the mode‐I fracture toughness (KIc) of Nash Point Shale at confining pressure simulating in situ conditions to approximately 1‐km depth. In the most favorable orientation, the pressure required to fracture the rock shell (injection pressure, Pinj) increases from 6.1 MPa at 2.2‐MPa confining pressure (Pc), to 34 MPa at 20‐MPa confining pressure. When fractures are forced to cross the shale bedding, the required injection pressures are 30.3 MPa (at Pc = 4.5 MPa) and 58 MPa (Pc = 20 MPa), respectively. Applying the model of Abou‐Sayed et al. (1978, https://doi.org/10.1029/JB083iB06p02851) to estimate the initial flaw size, we calculate that this pressure increase equates to an increase in KIc from 0.36 to 4.05 MPa·m1/2 as differential fluid pressure (Pinj − Pc) increases from 3.2 to 22.0 MPa. We conclude that the increasing pressure due to depth in the Earth will have a significant influence on fracture toughness, which is also a function of the inherent anisotropy.

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Section: Methodsmentioning

confidence: 99%

Fluid‐Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure

Gehne¹,

Inskip²,

Benson³

et al. 2020

JGR Solid Earth

Self Cite

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show abstract

“…We do not observe the

r \propto t^{1 false/ 2}

behavior, characteristic of diffusion‐controlled microseismicity. Realistic values of diffusivity for hydraulically fractured rock are considered to be 1.0 m

^{2}

^{- 1}

(

\sim 1

D) or less, which Figure shows is clearly not adequate to describe the observed spatiotemporal distribution (Gehne and Benson, ; Tan et al, ; Gehne and Benson, ). Instead, we observe microseismicity occurring near instantaneously across a range of distances from the injection point.…”

Section: Hydraulic Fracturing At Preston New Road Ukmentioning

confidence: 99%

Stress Transfer From Opening Hydraulic Fractures Controls the Distribution of Induced Seismicity

et al. 2020

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Understanding the dominant physical processes that cause fault reactivation due to fluid injection is vital to develop strategies to avoid and mitigate injection-induced seismicity. Injection-induced seismicity is a risk for several industries, including hydraulic fracturing, geothermal stimulation, oilfield waste disposal and carbon capture and storage, with hydraulic fracturing having been associated with some of the highest magnitude induced earthquakes (M > 5). As such, strict regulatory schemes have been implemented globally to limit the felt seismicity associated with operations. In the UK, a very strict "traffic light" system is currently in place. These procedures were employed several times during injection at the PNR-1z well at Preston New Road, Lancashire, UK, from October to December 2018. As injection proceeded, it became apparent to the operator that stages were interacting with a seismogenic planar structure, interpreted as a fault zone, with several M L > 0.5 events occurring. Microseismicity was clustered along this planar structure in a fashion that could not readily be explained through pore pressure diffusion or hydraulic fracture growth. Instead, we investigate the role of static elastic stress transfer created by the tensile opening of hydraulic fractures. We find that the spatial distributions of microseismicity are strongly correlated with areas that receive positive Mohr-Coulomb stress changes from the tensile fracture opening, while areas that receive negative Mohr-Coulomb stress change are quiescent. We conclude that the stressing due to tensile hydraulic fracture opening plays a significant role in controlling the spatiotemporal distribution of induced seismicity.

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“…As its surface is converted by oxygen ions, the sensor resistance returns to the initial value. The response of MOS sensor is affected by a series of factors, such as the number of surface oxygen ions, permeability 25 , sensor film thickness, temperature, and gas concentration. Reference 26 , 27 shows that the oxygen ion concentration on the sensor surface changes with different annealing temperature and noble metal doping, and the resistance value of the sensor in the air environment.…”

Section: Sensing Principlementioning

confidence: 99%

Simulation of gas sensing mechanism of porous metal oxide semiconductor sensor based on finite element analysis

Zhang

Wang

2021

Sci Rep

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In recent years, finite element analysis is increasingly adopted to simulate the mechanism of metal oxide semiconductor (MOS) resistive gas sensors. In this article, the chemical reaction engineering module in the COMSOL Multiphysics tool is used to describe the dynamic equilibrium process of oxygen ions in the sensor. The boundary conditions of temperature transfer, conductivity model, and mass transfer are applied to simulate the convection, diffusion, and penetration processes. The response of the sensor at different temperatures (445 K–521 K) and different target gas concentrations (1–500 ppm) is simulated. In this paper, the dynamic model of oxygen ions is used creatively as a bridge between gas concentration and sensor response instead of the traditional direct parameter fitting method. The simulated result of the surface oxygen ion control and permeability control model of the MOS gas sensor shows a good agreement with the real sensor. For explaining the principle of metal oxide semiconductor gas sensors simulations has been performed on COMSOL Multiphysics software. The proposed method in this paper is based on the underlying transfer logic of the sensor signal, it is expected to predict the sensor signal and assist the sensor design.

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Permeability enhancement through hydraulic fracturing: laboratory measurements combining a 3D printed jacket and pore fluid over-pressure

Cited by 37 publications

References 28 publications

Fluid‐Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure

Fluid‐Driven Tensile Fracture and Fracture Toughness in Nash Point Shale at Elevated Pressure

Stress Transfer From Opening Hydraulic Fractures Controls the Distribution of Induced Seismicity

Simulation of gas sensing mechanism of porous metal oxide semiconductor sensor based on finite element analysis

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