Detection and quantification of 3D hydraulic fractures with vertical borehole induction resistivity measurements

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. E259-E264 ◽  
Author(s):  
Kai Yang ◽  
Carlos Torres-Verdín ◽  
Ali E. Yılmaz
Keyword(s):  
Electrical Conductivity ◽  
Low Frequency ◽  
Hydraulic Fractures ◽  
Electrically Conductive ◽  
Resistivity Measurements ◽  
Effective Electrical Conductivity ◽  
Shale Formation ◽  
Logging Tool ◽  
Conductivity Contrast ◽  
Vertical Borehole

We have investigated the ability of low-frequency induction resistivity measurements to detect and appraise hydraulic fractures induced near vertical boreholes. Integral-equation-based simulations indicate that coplanar measurements can detect fractures when they are injected with electrically conductive proppant to increase their conductivity contrast with the shale background. Specifically, when a logging tool consisting of one transmitter and two receivers that are 1.2 and 1.5 m away is used to detect fractures with the effective electrical conductivity of [Formula: see text] in a homogeneous shale formation of [Formula: see text] conductivity, the measurements (1) can indicate the boundary of fractures intersecting with vertical boreholes by the signal spikes generated only when the tool enters/exits fractures, (2) can detect fractures as small as approximately 0.15 m and differentiate fractures up to approximately 10 m in width, (3) can detect fractures with height as small as 0.3 m, (4) can differentiate elliptical and rectangular fractures from each other if they exhibit the same width; e.g., they can discriminate if their widths are within approximately 0.4–10 m, and (5) are sensitive to the effective electrical conductivity of the fracture. A second logging tool consisting of one transmitter and two receivers that are 18 and 19.2 m away is found to be less useful in the detection and appraisal of hydraulic fractures induced near vertical boreholes.

scholarly journals Sensitivity analysis for the appraisal of hydrofractures in horizontal wells with borehole resistivity measurements

Geophysics ◽  
2013 ◽  
Vol 78 (4) ◽  
pp. D209-D222 ◽  
Author(s):  
David Pardo ◽  
Carlos Torres-Verdín
Keyword(s):  
High Frequency ◽  
Horizontal Well ◽  
Low Frequency ◽  
Horizontal Wells ◽  
Hydraulic Fractures ◽  
Electrically Conductive ◽  
Resistivity Measurements ◽  
Electromagnetic Measurements ◽  
Open Hole ◽  
Thin Disks

We numerically evaluate the possibility of using borehole electromagnetic measurements to diagnose and quantify hydraulic fractures that have been artificially generated in a horizontal well. Hydrofractures are modeled as thin disks perpendicular to the well and filled with either sand-based or electrically conductive proppant. The study focuses on the effect of thickness and length (radius) of hydrofractures to assess their effects on specific configurations of borehole-resistivity instruments. Numerical results indicate that several measurements (e.g., those obtained with low- and high-frequency solenoids) could be used to assess the thickness of a fracture. However, only low-frequency measurements performed with electrodes and large-spacing between transmitter and receivers (18 m) exhibit the necessary sensitivity to reliably and accurately estimate the length of long hydrofractures (up to 150 m) in open-hole wells. In the case of steel-cased wells, the casing acts as a long electrode, whereby conventional low-frequency short-spaced, through-casing measurements are suitable for the accurate diagnosis of long hydrofractures (up to 150 m in length).

A goal-oriented framework for rapid integral-equation-based simulation of borehole resistivity measurements of 3D hydraulic fractures

Geophysics ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. D123-D133 ◽  
Author(s):  
Kai Yang ◽  
Ali E. Yılmaz ◽  
Carlos Torres-Verdín
Keyword(s):  
Integral Equation ◽  
Method Of Moments ◽  
Low Frequency ◽  
Hydraulic Fractures ◽  
Approximate Methods ◽  
Electrically Conductive ◽  
Resistivity Measurements ◽  
Integral Equation Methods ◽  
Approximate Integral ◽  
Quantities Of Interest

We have developed a goal-oriented framework for fast integral-equation-based simulation of low-frequency borehole resistivity measurements of 3D arbitrarily shaped hydraulic fractures. The framework explores the possibility of applying various approximate integral-equation methods to simulate borehole electromagnetic (EM) measurements acquired in the vicinity of 3D hydraulic fractures generated with electrically conductive proppant. It includes four approximate methods that are progressively more accurate, costly, and rigorous. Each method is used to approximate the method-of-moments solution of the integral equation and to evaluate/extract quantities of interest, e.g., bucked signals detected at receivers. When compared with rigorous fast Fourier transform (FFT)-accelerated method-of-moments solutions, the numerical results obtained with the four methods indicate the following (1) All of the approximate methods capture the main features of the quantities of interest, e.g., the shape of detected signals. (2) Different approximate methods exhibit different accuracies and efficiencies in the simulation of EM scattering from various 3D fractures. (3) The identified approximate method achieves accurate results (error [Formula: see text]) while reducing the simulation time by a factor of 2–1000 compared with the FFT-accelerated rigorous method. Thus, our approximate simulation framework is a promising candidate for evaluating the Jacobian matrix in the fast inversion of borehole EM measurements to detect and assess the geometry of 3D hydraulic fractures generated with electrically conductive proppant.

Preparation and Characterization of Porous Si-Coated SiC Fiber Media

2004 ◽  
Vol 449-452 ◽  
pp. 233-236 ◽  
Author(s):  
Jun Suh Yu ◽  
B.S. Lee ◽  
Sung Churl Choi ◽  
Ji Hun Oh ◽  
Jae Chun Lee
Keyword(s):  
Electrical Conductivity ◽  
Silicon Content ◽  
Porous Si ◽  
Electrically Conductive ◽  
Electrode Distance ◽  
Sic Fiber ◽  
Effective Electrical Conductivity ◽  
The One ◽  
Fiber Preforms

Electrically conductive porous Si/SiC fiber media were prepared by infiltration of liquid silicon into porous carbon fiber preforms. The series rule of mixture for the effective electrical conductivity was applied to the disc shaped samples to estimate their silicon content, effective electrical conductivity and porosity. The electrical conductivity was estimated by assuming the disc sample as a plate of equivalent geometry, i.e., same thickness, electrode distance and volume. As the volumetric content of silicon in a sample increases from 0.026% to 0.97%, the estimated electrical conductivity increases from 0.17 S/cm to 2.09 S/cm. The porosity of the samples measured by Archimedes principle was in the range of 75~83% and 1~4% less than the one estimated by the series rule of mixture for the effective electrical conductivity.

Modeling of Low-Frequency Downhole Electrical Measurements for Mapping Proppant Distribution in Hydraulic Fractures in Casedhole Wells

SPE Journal ◽  
2018 ◽  
Vol 23 (06) ◽  
pp. 2147-2157 ◽  
Author(s):  
Peng Zhang ◽  
Mrinal K. Sen ◽  
Mukul M. Sharma ◽  
Jeff Gabelmann ◽  
David Glowka
Keyword(s):  
Electrical Potential ◽  
Synthetic Data ◽  
Low Frequency ◽  
Electrical Current ◽  
Hydraulic Fractures ◽  
Single Fracture ◽  
Electrical Measurements ◽  
Multiple Fractures ◽  
Electrically Conductive ◽  
Simulation Results

Summary A tool concept using downhole electrical measurements for mapping electrically conductive proppant in hydraulic fractures is presented in this paper. The method relies on direct excitation of the casing, which is expected to overcome the severe limitations of induction tools in casedhole wells. An array of insulating gaps is installed and cemented in place as a permanent part of the casing string. The envisioned electrical measurements are performed by imposing a voltage across each insulating gap, one at a time, before and after hydraulic-fracture operations. The voltages across other insulating gaps near the transmitter gap are recorded. The proposed tool's response to the geometry of a single fracture was modeled by solving for the electrical potential with a finite-volume method. Previous simulation results have shown that the electrically conductive proppant alters the path of the electrical current in the formation, and this is recorded as differential signals by the string of insulating gaps surrounding the source gap. The simulated differential signals are highly sensitive to a fracture's location, length, and orientation, and less sensitive to the fracture's aspect ratio. However, to enable the implementation of such a practical system, various aspects of the tool concept must be investigated further through simulations. Following our previous work, this paper focuses on the forward modeling of the tool's response to multiple fractures, which demonstrates the influence of these fractures on the signals, and provides important guidance for inverse modeling. Parametric inversion of fractures from synthetic data, generated by exciting various insulating gaps, is solved with very fast simulated annealing (VFSA). Simulation results show that, when multiple hydraulic fractures are present, the voltages measured at the receiver gaps are determined primarily by the fracture that is in direct contact with the excited section of casing. When two fractures touch the same casing section, they induce voltages very similar to those from a single fracture with the same conductivity and volume. Preliminary inversion results that use synthetic data computed from circular fractures indicate that the proposed VFSA can solve for the multiple fractures’ widths and radii at the same time, without requiring numerous forward simulations. Even with noisy synthetic data, VFSA can make good estimates of the fractures’ parameters. This indicates that the VFSA technique is a proper and robust inversion technique for the measured voltages at various receiver gaps.

Effect of Graphene Nanoplatelet Addition on the Conductive Behavior of Solution Mixing Processed Polylactide Biopolymer Nanocomposites

2019 ◽  
Author(s):  
Qi Zhang ◽  
Pierre Mertiny
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Conductive Polymer ◽  
Polymer Materials ◽  
Molding Process ◽  
Electrically Conductive ◽  
Fourfold Increase ◽  
Resistivity Measurements ◽  
Solution Blending ◽  
Anisotropic Thermal Conductivity

Abstract The fabrication of highly thermally and electrically conductive polymer materials is of interest for multiple applications, for example, in electronics packaging and biosensors. Polylactic acid (PLA), a commercially available and biodegradable polyesters, is widely used and studied since it is considered a environmentally friendly alternative to petrochemical-based synthetic polymers. In the present study, graphene nanoplatelets (GNP) reinforced PLA composites were prepared via solution blending followed by a compression molding process. Various physical and thermo-mechanical analyses were performed with the prepared composites. For instance, the electrical conductivity of PLA/GNP composites at various filler loadings was determined using four-point probe resistivity measurements. An electrical conductivity of 0.1 S/cm was achieved at a GNP loading of 12 wt%. Using the hot-disk transient plane source method, anisotropic thermal conductivity properties were evaluated. An in-plane and through-plane thermal conductivity of 0.87 W/mK and 0.58 W/mK was achieved with the addition of 6 wt% GNP, which is a nearly twofold and over fourfold increase compared to neat PLA, respectively.

Radio and Electrical Measurements on Glacial Streams

1987 ◽  
Vol 33 (114) ◽  
pp. 239-242
Author(s):  
M. E. R. Walford
Keyword(s):  
Electrical Conductivity ◽  
Water Channel ◽  
Water System ◽  
Low Frequency ◽  
Water Channels ◽  
Radiative Loss ◽  
Radio Waves ◽  
Electrical Measurements ◽  
Water Conductivity ◽  
Glacier Surface

AbstractWe discuss the suggestion that small underwater transmitters might be used to illuminate the interior of major englacial water channels with radio waves. Once launched, the radio waves would naturally tend to be guided along the channels until attenuated by absorption and by radiative loss. Receivers placed within the channels or at the glacier surface could be used to detect the signals. They would provide valuable information about the connectivity of the water system. The electrical conductivity of the water is of crucial importance. A surface stream on Storglaciären, in Sweden, was found, using a low-frequency technique, to have a conductivity of approximately 4 × 10−4 S m−1. Although this is several hundred times higher than the conductivity of the surrounding glacier ice, the contrast is not sufficient to permit us simply to use electrical conductivity measurements to establish the connectivity of englacial water channels. However, the water conductivity is sufficiently small that, under favourable circumstances, radio signals should be detectable after travelling as much as a few hundred metres along an englacial water channel. In a preliminary field experiment, we demonstrated semi quantitatively that radio waves do indeed propagate as expected, at least in surface streams. We conclude that under-water radio transmitters could be of real practical value in the study of the englacial water system, provided that sufficiently robust devices can be constructed. In a subglacial channel, however, we expect the radio range would be much smaller, the environment much harsher, and the technique of less practical value.

Polypyrrole/PU hybrid hydrogels: electrically conductive and fast self-healing for the potential application in body-monitor sensor

2021 ◽  
Author(s):  
Zhanyu Jia ◽  
Guangyao Li ◽  
Juan Wang ◽  
shouhua Su ◽  
Jie Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Potential Application ◽  
Self Healing ◽  
Electrically Conductive ◽  
Sensor Application ◽  
Hybrid Hydrogels ◽  
Health Monitor

Conductivity, self-healing and moderate mechanical properties are necessary for multifunctional hydrogels which have great potential in health-monitor sensor application. However, the combination of electrical conductivity, self-healing and good mechanical properties...

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

scholarly journals Electrically Conductive Networks from Hybrids of Carbon Nanotubes and Graphene Created by Laser Radiation

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1875
Author(s):  
Alexander Yu. Gerasimenko ◽  
Artem V. Kuksin ◽  
Yury P. Shaman ◽  
Evgeny P. Kitsyuk ◽  
Yulia O. Fedorova ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Laser Irradiation ◽  
Flexible Electronics ◽  
Threshold Energy ◽  
Wavelength Region ◽  
Hybrid Nanostructures ◽  
Graphene Sheets ◽  
Electrically Conductive ◽  
Walled Carbon Nanotubes

A technology for the formation of electrically conductive nanostructures from single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), and their hybrids with reduced graphene oxide (rGO) on Si substrate has been developed. Under the action of single pulses of laser irradiation, nanowelding of SWCNT and MWCNT nanotubes with graphene sheets was obtained. Dependences of electromagnetic wave absorption by films of short and long nanotubes with subnanometer and nanometer diameters on wavelength are calculated. It was determined from dependences that absorption maxima of various types of nanotubes are in the wavelength region of about 266 nm. It was found that contact between nanotube and graphene was formed in time up to 400 fs. Formation of networks of SWCNT/MWCNT and their hybrids with rGO at threshold energy densities of 0.3/0.5 J/cm2 is shown. With an increase in energy density above the threshold value, formation of amorphous carbon nanoinclusions on the surface of nanotubes was demonstrated. For all films, except the MWCNT film, an increase in defectiveness after laser irradiation was obtained, which is associated with appearance of C–C bonds with neighboring nanotubes or graphene sheets. CNTs played the role of bridges connecting graphene sheets. Laser-synthesized hybrid nanostructures demonstrated the highest hardness compared to pure nanotubes. Maximum hardness (52.7 GPa) was obtained for MWCNT/rGO topology. Regularity of an increase in electrical conductivity of nanostructures after laser irradiation has been established for films made of all nanomaterials. Hybrid structures of nanotubes and graphene sheets have the highest electrical conductivity compared to networks of pure nanotubes. Maximum electrical conductivity was obtained for MWCNT/rGO hybrid structure (~22.6 kS/m). Networks of nanotubes and CNT/rGO hybrids can be used to form strong electrically conductive interconnections in nanoelectronics, as well as to create components for flexible electronics and bioelectronics, including intelligent wearable devices (IWDs).

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