DEDUCTING DISPERSIVE PERMITTIVITY FROM LWD RESISTIVITY MEASUREMENTS

2019 ◽  
Author(s):  
Stein Ottar Stalheim
Keyword(s):  
Resistivity Measurements ◽  
Lwd Resistivity

REAL-TIME 2.5D INVERSION OF LWD RESISTIVITY MEASUREMENTS USING DEEP LEARNING FOR GEOSTEERING APPLICATIONS ACROSS FAULTED FORMATIONS

2021 ◽  
Author(s):  
Kyubo Noh ◽  
◽  
Carlos Torres-Verdín ◽  
David Pardo ◽  
◽  
...  
Keyword(s):  
Deep Learning ◽  
Real Time ◽  
Fault Plane ◽  
Synthetic Data ◽  
Field Measurements ◽  
Geological Structure ◽  
Inversion Method ◽  
Adaptive Finite Element ◽  
Resistivity Measurements ◽  
Lwd Resistivity

We develop a Deep Learning (DL) inversion method for the interpretation of 2.5-dimensional (2.5D) borehole resistivity measurements that requires negligible online computational costs. The method is successfully verified with the inversion of triaxial LWD resistivity measurements acquired across faulted and anisotropic formations. Our DL inversion workflow employs four independent DL architectures. The first one identifies the type of geological structure among several predefined types. Subsequently, the second, third, and fourth architectures estimate the corresponding spatial resistivity distributions that are parameterized (1) without the crossings of bed boundaries or fault plane, (2) with the crossing of a bed boundary but without the crossing of a fault plane, and (3) with the crossing of the fault plane, respectively. Each DL architecture employs convolutional layers and is trained with synthetic data obtained from an accurate high-order, mesh-adaptive finite-element forward numerical simulator. Numerical results confirm the importance of using multi-component resistivity measurements -specifically cross-coupling resistivity components- for the successful reconstruction of 2.5D resistivity distributions adjacent to the well trajectory. The feasibility and effectiveness of the developed inversion workflow is assessed with two synthetic examples inspired by actual field measurements. Results confirm that the proposed DL method successfully reconstructs 2.5D resistivity distributions, location and dip angles of bed boundaries, and the location of the fault plane, and is therefore reliable for real-time well geosteering applications.

On the depth of detection of logging-while-drilling resistivity measurements for looking-around and looking-ahead applications

2020 ◽  
Vol 8 (3) ◽  
pp. SL151-SL158
Author(s):  
Hu Li ◽  
Jun Zhu ◽  
Yanchun Xiong ◽  
Gang Liu ◽  
Yuanshi Tian ◽  
...  
Keyword(s):  
Data Interpretation ◽  
Detection Capability ◽  
Vertical Wells ◽  
Detection Thresholds ◽  
Resistivity Measurements ◽  
Resistivity Logs ◽  
Logging While Drilling ◽  
Definition Of ◽  
Azimuthal Resistivity ◽  
Lwd Resistivity

The depth of detection (DOD), which is an important concept in logging data interpretation, describes the detection capability of the borehole measurements. We have extended the definition of DOD for azimuthal information, namely, the geosignal delivered by azimuthal resistivity tools, to resistivity logs in logging-while-drilling (LWD) applications. Instead of using the radial geometric factor, the detection thresholds in predicting a geologic boundary are used to describe the DOD of a measurement. This definition unifies the criteria to evaluate the detectability of different borehole measurements, such as LWD resistivity measurements and geosignals. It also can be generalized to other kinds of well logging methods in LWD applications. Using the proposed definition, we analyze the detection capability of the LWD resistivity measurements in looking-around and looking-ahead applications; they provide more tangible descriptions. In vertical or near-vertical wells, the definition provides an indicator to evaluate the capability and reliability of looking ahead of deep/ultradeep LWD resistivity tools. The investigations on the influence of the DOD on the distance-to-boundary inversion, which can help in developing a robust and accurate inversion scheme, also are presented and discussed.

Anisotropy and True Formation Resistivity Measurements with a New LWD Resistivity Sensor

2012 ◽  
Author(s):  
Michael Bittar ◽  
Hsu-Hsiang Wu ◽  
Shanjun Li ◽  
Mohammed Bayrakdar
Keyword(s):  
Resistivity Measurements ◽  
Formation Resistivity ◽  
Lwd Resistivity

Direct Observation of the Diffusionless β → β + ω Transformation in Titanium Alloys

1971 ◽  
Vol 29 ◽  
pp. 122-123
Author(s):  
N. E. Paton ◽  
D. de Fontaine ◽  
J. C. Williams
Keyword(s):  
Electron Microscope ◽  
Titanium Alloys ◽  
Direct Observation ◽  
Dark Field ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Selected Area Electron Diffraction ◽  
Ti Alloys ◽  
Thin Foils ◽  
Field Device

The electron microscope has been used to study the diffusionless β → β + ω transformation occurring in certain titanium alloys at low temperatures. Evidence for such a transformation was obtained by Cometto et al by means of x-ray diffraction and resistivity measurements on a Ti-Nb alloy. The present work shows that this type of transformation can occur in several Ti alloys of suitable composition, and some of the details of the transformation are elucidated by means of direct observation in the electron microscope.Thin foils were examined in a Philips EM-300 electron microscope equipped with a uniaxial tilt, liquid nitrogen cooled, cold stage and a high resolution dark field device. Selected area electron diffraction was used to identify the phases present and the ω-phase was imaged in dark field by using a (101)ω reflection. Alloys were water quenched from 950°C, thinned, and mounted between copper grids to minimize temperature gradients in the foil.

In-situ electrical-resistivity measurements in the high-voltage electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 68-69
Author(s):  
W. E. King
Keyword(s):  
Electrical Resistivity ◽  
Electron Microscope ◽  
High Voltage ◽  
Resistivity Measurements ◽  
Voltage Electron ◽  
High Voltage Electron Microscope ◽  
High Voltage Electron ◽  
Wide Range ◽  
Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

Structural, optical and electrical properties of thermal evaporated nano sized In2Te3 thin films

2018 ◽  
Vol 1 (1) ◽  
pp. 21-25
Author(s):  
R Revathi ◽  
R Karunathan
Keyword(s):  
Thin Films ◽  
Negative Temperature Coefficient ◽  
Thermal Evaporation ◽  
Structural Parameters ◽  
Negative Temperature ◽  
Resistivity Measurements ◽  
Allowed Transition ◽  
Evaporation Technique ◽  
Indium Telluride ◽  
Made In

Indium Telluride thin films were prepared by thermal evaporation technique. Films were annealed at 573K under vacuum for an hour. Both as-deposited and annealed films were used for characterization. The structural parameters were discussed on the basis of annealing effect for a film of thickness 1500 Å. Optical analysis was carried out on films of different thicknesses for both as - deposited and annealed samples. Both the as- deposited and annealed films exhibit direct and allowed transition. Electrical resistivity measurements were made in the temperature range of 303-473 K using Four-probe method. The calculated resistivity value is of the order of 10-6 ohm meter. The activation energy value decreases with increasing film thickness. The negative temperature coefficient indicates the semiconducting nature of the film.

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