scholarly journals Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

2017 ◽  
Vol 44 (7) ◽  
pp. 3109-3118 ◽  
Author(s):  
Yusuke Mukuhira ◽  
Hirokazu Moriya ◽  
Takatoshi Ito ◽  
Hiroshi Asanuma ◽  
Markus Häring
Keyword(s):  
Pore Pressure ◽  
Low Pressure ◽  
Hydraulic Stimulation ◽  
Permeability Enhancement ◽  
Subcritical Fracture

scholarly journals The influence of fault reactivation on injection-induced dynamic triggering of permeability evolution

2020 ◽  
Vol 223 (3) ◽  
pp. 1481-1496
Author(s):  
Elif Cihan Yildirim ◽  
Kyungjae Im ◽  
Derek Elsworth
Keyword(s):  
Pore Pressure ◽  
Fluid Pressure ◽  
Fault Reactivation ◽  
Permeability Evolution ◽  
Fracture Permeability ◽  
Permeability Enhancement ◽  
Pressure Pulses ◽  
Fracture Sealing ◽  
Permeability Increase ◽  
Pressure Driven

SUMMARY Mechanisms controlling fracture permeability enhancement during injection-induced and natural dynamic stressing remain unresolved. We explore pressure-driven permeability (k) evolution by step-increasing fluid pressure (p) on near-critically stressed laboratory fractures in shale and schist as representative of faults in sedimentary reservoirs/seals and basement rocks. Fluid is pulsed through the fracture with successively incremented pressure to first examine sub-reactivation permeability response that then progresses through fracture reactivation. Transient pore pressure pulses result in a permeability increase that persists even after the return of spiked pore pressure to the null background level. We show that fracture sealing is systematically reversible with the perturbing pressure pulses and pressure-driven permeability enhancement is eminently reproducible even absent shear slip and in the very short term (order of minutes). These characteristics of the observed fracture sealing following a pressure perturbation appear similar to those of the response by rate-and-state frictional healing upon stress/velocity perturbations. Dynamic permeability increase scales with the pore pressure magnitude and fracture sealing controls the following per-pulse permeability increase, both in the absence and presence of reactivation. However, initiation of the injection-induced reactivation results in a significant increase in the rate of permeability enhancement (dk/dp). These results demonstrate the role of frictional healing and sealing of fractures at interplay with other probable processes in pore pressure-driven permeability stimulation, such as particle mobilization.

scholarly journals Novel chemical stimulation for geothermal reservoirs by chelating agent driven selective mineral dissolution in fractured rocks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Noriaki Watanabe ◽  
Kaori Takahashi ◽  
Ryota Takahashi ◽  
Kengo Nakamura ◽  
Yusuke Kumano ◽  
...  
Keyword(s):  
Fractured Rocks ◽  
Chelating Agent ◽  
Chemical Stimulation ◽  
Mineral Dissolution ◽  
Moderate Intensity ◽  
Geothermal Systems ◽  
Confining Stress ◽  
Traditional Methods ◽  
Hydraulic Stimulation ◽  
Permeability Enhancement

AbstractImproving geothermal systems through hydraulic stimulation to create highly permeable fractured rocks can induce seismicity. Therefore, the technique must be applied at a moderate intensity; this has led to concerns of insufficient permeability enhancement. Adding chemical stimulation can mitigate these issues, but traditional methods using strong mineral acids have challenges in terms of achieving mineral dissolution over long distances and highly variable fluid chemistry. Here, we demonstrate a novel chemical stimulation method for improving the permeability of rock fractures using a chelating agent that substantially enhances the dissolution rate of specific minerals to create voids that are sustained under crustal stress without the challenges associated with the traditional methods. Applying this agent to fractured granite samples under confining stress at 200 °C in conjunction with 20 wt% aqueous solutions of sodium salts of environmentally friendly chelating agents (N-(2-hydroxyethyl)ethylenediamine-N, N′, N′-triacetic acid and N, N-bis(carboxymethyl)-l-glutamic acid) at pH 4 was assessed. A significant permeability enhancement of up to approximately sixfold was observed within 2 h, primarily due to the formation of voids based on the selective dissolution of biotite. These results demonstrate a new approach for chemical stimulation.

scholarly journals Permeability Enhancement From a Hydraulic Stimulation Imaged With Ground Penetrating Radar

2020 ◽  
Vol 47 (17) ◽  
Author(s):  
A. Shakas ◽  
H. Maurer ◽  
P.‐L. Giertzuch ◽  
M. Hertrich ◽  
D. Giardini ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Hydraulic Stimulation ◽  
Permeability Enhancement ◽  
Ground Penetrating

scholarly journals Using Microseismicity to Estimate Formation Permeability for Geological Storage of CO2

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
D. A. Angus ◽  
J. P. Verdon
Keyword(s):  
Pore Pressure ◽  
Effective Stress ◽  
Large Scale ◽  
Microseismic Monitoring ◽  
Seepage Force ◽  
Triggering Mechanism ◽  
Hydraulic Stimulation ◽  
Microseismic Data ◽  
Order Of Magnitude ◽  
Force Mechanism

We investigate two approaches for estimating formation permeability based on microseismic data. The two approaches differ in terms of the mechanism that triggers the seismicity: pore-pressure triggering mechanism and the so-called seepage-force (or effective stress) triggering mechanism. Based on microseismic data from a hydraulic fracture experiment using water and supercritical CO2 injection, we estimate permeability using the two different approaches. The microseismic data comes from two hydraulic stimulation treatments that were performed on two formation intervals having similar geological, geomechanical, and in situ stress conditions, yet different injection fluid was used. Both approaches (pore-pressure triggering, and the seepage-force triggering) provide estimates of permeability within the same order of magnitude. However, the seepage-force mechanism (i.e., effective stress perturbation) provides more consistent estimates of permeability between the two different injection fluids. The results show that permeability estimates using microseismic monitoring have strong potential to constrain formation permeability limitations for large-scale CO2 injection.

scholarly journals Permeability enhancement from a hydraulic stimulation imaged with Ground Penetrating Radar

2020 ◽  
Author(s):  
Alexis Shakas ◽  
Hansruedi Maurer ◽  
Peter-Lasse Giertzuch ◽  
Marian Hertrich ◽  
Domenico Giardini ◽  
...  
Keyword(s):  
Ground Penetrating Radar ◽  
Hydraulic Stimulation ◽  
Permeability Enhancement ◽  
Ground Penetrating

Effects of Electrical Discharges in Low Pressure Gases on the Morphology of Polyethylene Crystals

1974 ◽  
Vol 32 ◽  
pp. 544-545
Author(s):  
L.H. Bolz ◽  
D.H. Reneker
Keyword(s):  
Power Distribution ◽  
Electrical Discharge ◽  
Dielectric Breakdown ◽  
Ionic Species ◽  
Low Pressure ◽  
Polymer Surfaces ◽  
Electrical Discharges ◽  
Adhesive Bonds ◽  
Power Distribution Lines ◽  
Modification Of The Surface

The attack, on the surface of a polymer, by the atomic, molecular and ionic species that are created in a low pressure electrical discharge in a gas is interesting because: 1) significant interior morphological features may be revealed, 2) dielectric breakdown of polymeric insulation on high voltage power distribution lines involves the attack on the polymer of such species created in a corona discharge, 3) adhesive bonds formed between polymer surfaces subjected to such SDecies are much stronger than bonds between untreated surfaces, 4) the chemical modification of the surface creates a reactive surface to which a thin layer of another polymer may be bonded by glow discharge polymerization.

Field ion microscopy

1988 ◽  
Vol 46 ◽  
pp. 434-435
Author(s):  
Gert Ehrlich
Keyword(s):  
Low Temperature ◽  
Sample Surface ◽  
Low Pressure ◽  
Radius Of Curvature ◽  
Field Ion Microscopy ◽  
Phosphor Screen ◽  
Ion Microscopy ◽  
Field Ion Microscope

The field ion microscope, devised by Erwin Muller in the 1950's, was the first instrument to depict the structure of surfaces in atomic detail. An FIM image of a (111) plane of tungsten (Fig.l) is typical of what can be done by this microscope: for this small plane, every atom, at a separation of 4.48Å from its neighbors in the plane, is revealed. The image of the plane is highly enlarged, as it is projected on a phosphor screen with a radius of curvature more than a million times that of the sample. Müller achieved the resolution necessary to reveal individual atoms by imaging with ions, accommodated to the object at a low temperature. The ions are created at the sample surface by ionization of an inert image gas (usually helium), present at a low pressure (< 1 mTorr). at fields on the order of 4V/Å.

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