Numerical modeling and interpretation of drillstring waves

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1569-1581 ◽  
Author(s):  
Flavio Poletto ◽  
Massimo Malusa ◽  
Francesco Miranda
Keyword(s):  
Signal Processing ◽  
Numerical Modeling ◽  
Boundary Conditions ◽  
Transmission Line ◽  
Reflection Coefficients ◽  
Drill Bit ◽  
Noise Sources ◽  
Numeric Modeling ◽  
Joint Contribution ◽  
Group Velocities

Drill‐bit seismic and pilot seismograms contain drillstring periodicities from signal and environmental noise sources. These coherent components are similar in seismic‐while‐drilling correlations, and their joint contribution may cause distortions in signal processing. Numeric modeling of the drillstring transmission line is used to correctly interpret the axial and torsional events with similar propagating modes of signal and noise. The reflection coefficients are computed for drillstrings of arbitrary materials, and their average mechanical features are related to the axial and torsional group velocities obtained by the dispersion equations. Fitting of the periodical components in the real seismograms is used to automatically correct the drill‐bit pilot delays and to estimate the surface and downhole boundary conditions.

Upon Impact Numerical Modeling of Foam Materials

2017 ◽  
Vol 54 (2) ◽  
pp. 195-202
Author(s):  
Vasile Nastasescu ◽  
Silvia Marzavan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Numerical Analysis ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
General Character ◽  
Foam Material ◽  
Various Boundary Conditions ◽  
Specific Behaviour

The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.

scholarly journals Location of agate geodes in Permian deposits of Simota gully using the GPR

2021 ◽  
Author(s):  
Michał Mierczak ◽  
Jerzy Karczewski
Keyword(s):  
Signal Processing ◽  
High Frequency ◽  
Electromagnetic Energy ◽  
Reflection Coefficients ◽  
Electric Permittivity ◽  
Pyroclastic Deposits ◽  
High Attenuation ◽  
Subsurface Geology ◽  
Study Test

AbstractThe article describes the establishment of the location of agate geodes using the GPR method in the area of the Simota gully (Lesser Poland Voivodeship). Agates (a multicolored variety of gemstone of chalcedony group) have multifaceted values that informed their study. Traditional methods of geode location are less reliable, hence the attempt to use the GPR method. Measurements were taken at two study test sites with subsurface geology of weathered melaphyre and pyroclastic deposits using a GPR system (ProEx). A high-frequency antenna (1.6 GHz) was used along with the pre-established profiles of lengths of 6-m and 10-cm intervals. Furthermore, simple soil tests using the soil sampler tool were made prior to the GPR measurement. The GPR results show significant high attenuation of the electromagnetic energy interpreted to be due to clay components of the regolith. Advanced signal processing procedures (such as the attribute of the signal) were used on the data for better enhancement that aided interpretation. Other anomalies depicted on the radargrams were thought to be the presence of roots, pieces of melaphyres-targeted agates. Furtherance to ascertain the reflection coefficients as recorded on the GPR data, in situ samples (root pieces, melaphyres, agates) taken were tested in the laboratory for electric permittivity property. Based on the interpretation results, several agate geodes were dug out from the ground.

scholarly journals Numerical Modeling of the Motion of the Flat Textile Structures

2011 ◽  
Vol 2011 ◽  
pp. 1-8
Author(s):  
Piotr Szablewski
Keyword(s):  
Numerical Modeling ◽  
Boundary Conditions ◽  
Discrete Model ◽  
Gravity Force ◽  
Dynamic Conditions ◽  
Textile Structure ◽  
Sewing Thread ◽  
Lagrange’S Equations ◽  
Lagrange's Equations ◽  
Time Boundary

In many problems from the field of textile engineering (e.g., fabric folding, motion of the sewing thread) it is necessary to investigate the motion of the objects in dynamic conditions, taking into consideration the influence of the forces of inertia and changing in the time boundary conditions. This paper deals with the model analysis of the motion of the flat textile structure using Lagrange's equations in two variants: without constraints and with constraints. The motion of the objects is under the influence of the gravity force. Lagrange's equations have been used for discrete model of the structure.

scholarly journals Structural Health Monitoring of Steel Pipes under Different Boundary Conditions and Choice of Signal Processing Techniques

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Rais Ahmad ◽  
Tribikram Kundu
Keyword(s):  
Signal Processing ◽  
Boundary Conditions ◽  
Fourier Transforms ◽  
Guided Wave ◽  
Continuous Wavelet ◽  
Mother Wavelet ◽  
Different Boundary Conditions ◽  
Steel Pipes ◽  
Processing Techniques ◽  
Signal Processing Techniques

Guided wave technique is an efficient method for monitoring structural integrity by detecting and forecasting possible damages in distributed pipe networks. Efficient detection depends on appropriate selection of guided wave modes as well as signal processing techniques. Fourier analysis and wavelet analysis are two popular signal processing techniques that provide a flexible set of tools for solving various fundamental problems in science and engineering. In this paper, effective ways of using Fourier and Wavelet analyses on guided wave signals for detecting defects in steel pipes are discussed for different boundary conditions. This research investigates the effectiveness of Fourier transforms and Wavelet analysis in detecting defects in steel pipes. Cylindrical Guided waves are generated by piezo-electric transducers and propagated through the pipe wall boundaries in a pitch-catch system. Fourier transforms of received signals give information regarding the propagating guided wave modes which helps in detecting defects by selecting appropriate modes that are affected by the presence of defects. Continuous wavelet coefficients are found to be sensitive to defects. Several types of mother wavelet functions such as Daubechies, Symlet, and Meyer have been used for the continuous wavelet transform to investigate the most suitable wavelet function for defect detection. This research also investigates the effect of different boundary conditions on wavelet transforms for different mother wavelet functions.

Boundary conditions for the numerical solution of wave propagation problems

Geophysics ◽  
1978 ◽  
Vol 43 (6) ◽  
pp. 1099-1110 ◽  
Author(s):  
Albert C. Reynolds
Keyword(s):  
Wave Propagation ◽  
Reflection Coefficient ◽  
Finite Difference ◽  
Boundary Conditions ◽  
Numerical Solution ◽  
Neumann Boundary ◽  
Synthetic Seismograms ◽  
Neumann Boundary Conditions ◽  
Numerical Calculations ◽  
Reflection Coefficients

Many finite difference models in use for generating synthetic seismograms produce unwanted reflections from the edges of the model due to the use of Dirichlet or Neumann boundary conditions. In this paper we develop boundary conditions which greatly reduce this edge reflection. A reflection coefficient analysis is given which indicates that, for the specified boundary conditions, smaller reflection coefficients than those obtained for Dirichlet or Neumann boundary conditions are obtained. Numerical calculations support this conclusion.

scholarly journals Application of transmission-line super theory to classical transmission lines with risers

2015 ◽  
Vol 13 ◽  
pp. 161-168 ◽  
Author(s):  
R. Rambousky ◽  
J. Nitsch ◽  
S. Tkachenko
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Ground Plane ◽  
Reflection Coefficients ◽  
Geometrical Parameters ◽  
Horizontal Line ◽  
Line Configuration ◽  
Entire Line ◽  
Line Parallel ◽  
Horizontal Part

Abstract. By applying the Transmission-Line Super Theory (TLST) to a practical transmission-line configuration (two risers and a horizontal part of the line parallel to the ground plane) it is elaborated under which physical and geometrical conditions the horizontal part of the transmission-line can be represented by a classical telegrapher equation with a sufficiently accurate description of the physical properties of the line. The risers together with the part of the horizontal line close to them are treated as separate lines using the TLST. Novel frequency and local dependent reflection coefficients are introduced to take into account the action of the bends and their radiation. They can be derived from the matrizant elements of the TLST solution. It is shown that the solution of the resulting network and the TLST solution of the entire line agree for certain line configurations. The physical and geometrical parameters for these corresponding configurations are determined in this paper.

Research of Interleaved Code Applied in XCP Signal Processing

2012 ◽  
Vol 433-440 ◽  
pp. 3433-3438
Author(s):  
Zhi Cheng Jia ◽  
Xiao Hua Song ◽  
Yong Jun Li ◽  
Yan Zhang ◽  
Ning Liu
Keyword(s):  
Signal Processing ◽  
Velocity Profile ◽  
Transmission Line ◽  
Time Use ◽  
Data Transmission ◽  
Water Velocity ◽  
Processing Technology ◽  
Observation Instruments ◽  
Current Profiler ◽  
Fast Access

The XCP(eXpendable Current Profiler, XCP) is a one-time use of the current profiler observation instruments which is cheap, fast access to the parameters of the water velocity profile. The signal processing is an important part of the research of XCP. The paper discusses the coding study in the signal processing technology, analysises the interference and noise of the transmission line, uses the interleaved code method for reducing errors to improve the reliability of the communication, and simulates the interleaving encoding and decoding system by the Systemview tool, demonstrates the reliability and feasibility of data transmission by using interleaved coded.

High-Precision Drill Bit Tracking

2021 ◽  
Author(s):  
Marianne Houbiers ◽  
Sascha Bussat ◽  
Florian Schopper ◽  
Fredrik Hansteen
Keyword(s):  
High Precision ◽  
Lateral Position ◽  
Optimal Placement ◽  
Drill Bit ◽  
Noise Sources ◽  
Position Uncertainty ◽  
Passive Seismic ◽  
Continuous Stream ◽  
Well Trajectory ◽  
Passive Measurements

Abstract The lateral well position uncertainty of magnetic/gyro MWD measurements can often exceed the requirements regarding anti-collision, for optimal placement of infill wells between existing producers, or for hitting targets with limited geological extent. The positional uncertainty can be significantly reduced by implementing high-precision drill-bit localization using passive seismic data. Consequently, not only drilling risks can be reduced, but optimal reservoir drainage is ensured as well. By utilizing passive seismic recordings from the seafloor, we can "listen" to the noise generated by the BHA while drilling. Despite various noise sources in the vicinity (e.g. vessels and rigs), advanced data processing and the combination of hundreds of seafloor receivers spread above the ongoing drilling, enable us to detect the drilling signal and locate the drill bit. Whereas the magnetic and gyro MWD tools have errors that accumulate with measured depth, each bit position derived from seismic (usually every 90 seconds) is completely independent. For horizontal sections, the error does not increase with measured depth, and hence can provide improved lateral accuracy. No additional BHA tool is required and the measurements are neither dependent on the magnetic nor gravitational field. Moreover, the passive seismic measurements can be used to obtain an improved lateral well position estimate. This is done by optimizing the azimuth information of the well trajectory in the minimum curvature method. A lateral uncertainty measure can be derived from the residuals between the passive measurements and the updated well path. Since 2018, we have used the continuous stream of passive data from permanent seafloor sensors at the Grane field with its reservoir depth of around 1800 m TVDSS to follow all wells with this drill bit tracking scheme. Lateral deviations from the magnetic/gyro measurements of up to 20m have been observed. The lateral position uncertainty can be as low as a couple of meters under optimal conditions.

Sign in / Sign up

Export Citation Format

Share Document