Rock Physics Diagnostics as a prerequisite for optimal Petrophysics

2021 ◽  
Author(s):  
A. Mathur
Keyword(s):  
Model Building ◽  
Rock Physics ◽  
Original Form ◽  
Variable Porosity ◽  
Depositional Processes ◽  
Sonic Log ◽  
Empirical Relations ◽  
Velocity Relationship ◽  
Petrophysical Model

One of the key outputs from petrophysical evaluation is porosity. Sonic log is considered as one of the logs for deriving petrophysical volumes including porosity. However, the sonic data might not be always suitable to be included in the petrophysical model even if the quality of the log is quite good. One of the key reasons lies behind the variable porosity-velocity relationship for different types of formations attributed to post depositional processes. Without performing proper rock physics diagnostics before petrophysics model building can create inconsistencies in the petrophysical volumes as well as force the petrophysicist to use unreasonable endpoints for matrix or fluid. In this paper, an attempt is made to perform rock physics diagnostics using Wyllie-time-average and Raymer-Hunt-Gardner relations, drawing conclusion on the consolidation state of the rock, followed by computation of porosity from sonic using these relations. Later, rock physics diagnostic using theoretical rock physics models is carried out to confirm and complement this understanding of rock’s consolidation state. The results show that even though these empirical relations in their original form are useful and widely used but it is not quite suitable for unconsolidated and weakly cemented (poorly consolidated) formations or at least cannot justify the porosity-velocity trend in the data. Here computed sonic porosity is compared with field calibrated density porosity. It could be seen from this study that, in order to match sonic porosity with density porosity, an unreasonable matrix/fluid endpoints or non-theoretical empirical fitting coefficient is required. Since, this might not always be the case, a proper assessment using rock physics diagnostic should be carried out before incorporating sonic data into the petrophysical model.

scholarly journals The Use of Model Atmospheres for Temperature-Gravity Calibration

1973 ◽  
Vol 54 ◽  
pp. 173-221
Author(s):  
J. C. Pecker
Keyword(s):  
Model Building ◽  
Stellar Atmosphere ◽  
Line Formation ◽  
Early Type ◽  
New Concepts ◽  
Total Luminosity ◽  
Classical Models ◽  
Early Type Stars ◽  
Two Parameters

Regardless of the degree of elaboration of series of models, just how can they be used for calibration purposes? And how much is this calibration sensitive to the quality of the model theory? These two questions are the basis of our discussion, which covers : I – The general principles of the use of model atmospheres in stellar calibration (1 – The two dimensional classifications; 2 – The use of the total luminosity; 3 – The cases of Vega and Sirius; 4 – The calibration of ST – Teff relation); II – The failures of the two parameters model atmospheres (1 – The observational need for more-than-two-parameters classification; 2 – The abundance of elements, the line formation, and the model atmospheres; 3 – Various sources of unadequacy of models; 4 – Envelopes or shell features; their influence on model-building; 5 – The case of HD 45677. Diagnostic of early-type stars; 6 – Various unexplained spectral features); III – The present state of the model factory (1 – The classical models; 2 – New concepts in the description of a stellar atmosphere; 3 – New approaches in model making; 4 – Conclusions).

Integrated VTI model building with seismic data, geologic information, and rock-physics modeling — Part 1: Theory and synthetic test

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. C177-C191 ◽  
Author(s):  
Yunyue Li ◽  
Biondo Biondi ◽  
Robert Clapp ◽  
Dave Nichols
Keyword(s):  
Seismic Data ◽  
Seismic Anisotropy ◽  
Model Building ◽  
Rock Physics ◽  
Seismic Inversion ◽  
Additional Information ◽  
Synthetic Test ◽  
Rock Physics Modeling ◽  
Physics Modeling ◽  
Geologic Information

Seismic anisotropy plays an important role in structural imaging and lithologic interpretation. However, anisotropic model building is a challenging underdetermined inverse problem. It is well-understood that single component pressure wave seismic data recorded on the upper surface are insufficient to resolve a unique solution for velocity and anisotropy parameters. To overcome the limitations of seismic data, we have developed an integrated model building scheme based on Bayesian inference to consider seismic data, geologic information, and rock-physics knowledge simultaneously. We have performed the prestack seismic inversion using wave-equation migration velocity analysis (WEMVA) for vertical transverse isotropic (VTI) models. This image-space method enabled automatic geologic interpretation. We have integrated the geologic information as spatial model correlations, applied on each parameter individually. We integrate the rock-physics information as lithologic model correlations, bringing additional information, so that the parameters weakly constrained by seismic are updated as well as the strongly constrained parameters. The constraints provided by the additional information help the inversion converge faster, mitigate the ambiguities among the parameters, and yield VTI models that were consistent with the underlying geologic and lithologic assumptions. We have developed the theoretical framework for the proposed integrated WEMVA for VTI models and determined the added information contained in the regularization terms, especially the rock-physics constraints.

Synthetic Sonic Log Generation With Machine Learning: A Contest Summary From Five Methods

2021 ◽  
Vol 62 (4) ◽  
pp. 393-406
Author(s):  
Yanxiang Yu ◽  
◽  
Chicheng Xu ◽  
Siddharth Misra ◽  
Weichang Li ◽  
...  
Keyword(s):  
Machine Learning ◽  
Test Data ◽  
Short Term Memory ◽  
Rock Physics ◽  
Training Data ◽  
Machine Learning Techniques ◽  
Blind Test ◽  
Data Set ◽  
Benchmark Model ◽  
Sonic Log

Compressional and shear sonic traveltime logs (DTC and DTS, respectively) are crucial for subsurface characterization and seismic-well tie. However, these two logs are often missing or incomplete in many oil and gas wells. Therefore, many petrophysical and geophysical workflows include sonic log synthetization or pseudo-log generation based on multivariate regression or rock physics relations. Started on March 1, 2020, and concluded on May 7, 2020, the SPWLA PDDA SIG hosted a contest aiming to predict the DTC and DTS logs from seven “easy-to-acquire” conventional logs using machine-learning methods (GitHub, 2020). In the contest, a total number of 20,525 data points with half-foot resolution from three wells was collected to train regression models using machine-learning techniques. Each data point had seven features, consisting of the conventional “easy-to-acquire” logs: caliper, neutron porosity, gamma ray (GR), deep resistivity, medium resistivity, photoelectric factor, and bulk density, respectively, as well as two sonic logs (DTC and DTS) as the target. The separate data set of 11,089 samples from a fourth well was then used as the blind test data set. The prediction performance of the model was evaluated using root mean square error (RMSE) as the metric, shown in the equation below: RMSE=sqrt(1/2*1/m* [∑_(i=1)^m▒〖(〖DTC〗_pred^i-〖DTC〗_true^i)〗^2 + 〖(〖DTS〗_pred^i-〖DTS〗_true^i)〗^2 ] In the benchmark model, (Yu et al., 2020), we used a Random Forest regressor and conducted minimal preprocessing to the training data set; an RMSE score of 17.93 was achieved on the test data set. The top five models from the contest, on average, beat the performance of our benchmark model by 27% in the RMSE score. In the paper, we will review these five solutions, including preprocess techniques and different machine-learning models, including neural network, long short-term memory (LSTM), and ensemble trees. We found that data cleaning and clustering were critical for improving the performance in all models.

scholarly journals Celebration of childbirth through dance and the demystification of the male child in the Igbo Patriarchal Society: A decisive exposition

2020 ◽  
Vol 7 (15) ◽  
pp. 191-209
Author(s):  
Christian Chima Chukwu ◽  
Ignatius Sunday Ume
Keyword(s):  
Y Chromosome ◽  
Oral Tradition ◽  
Special Kind ◽  
Male Gender ◽  
Male Child ◽  
Original Form ◽  
Girl Child ◽  
Patriarchal Society ◽  
Good Music

Celebration of childbirth, among the Igbo, is looked upon as an occasion of feasting and so every festal feature, especially good music is made available as a mark of thanksgiving to God. The birth of a new child is announced with a special kind of song called irri muo, and it is sung in celebration of the birth. Songs sung at childbirth are called umanwa, while in neighbouring communities, they are egwu omugho. Umanwa music is exclusively performed by women, and has survived until today in its original form through oral tradition. This paper, therefore, examines the celebration of childbirth through dance and the demystification of the male child in the Igbo Patriarchal Society. Among the findings, the paper acknowledges that there is always some excitement, merriment, joy and intoxication, mixed with some sparks of faith when the new entrant is added to a household. In addition, the paper recognizes that women are never fully recognized as mothers until the birth of a boy child. Disturbing as the preference is, this paper wonders and questions why women are being easily ridiculed, subjugated and divorced when and where the Y-chromosome, the sole determinant of the birth of the boy child is the exclusive preserve of the male gender. With this, the paper argues that since human personality, a prerogative and quality of every human being does not rest on gender, but on ability; the emphasis on the boy child is absolutely unnecessary because it does not add anything to ability. The paper further calls on the educated elite to enlighten their people to be aware that the dignity of the girl child is fundamentally, essentially and unquestionably equal to the dignity of the boy child. Finally, the paper concludes that, the male child has not in most cases fulfilled the long awaited expectations of being the second father in the house.

Introduction to this special section: Rock physics

2019 ◽  
Vol 38 (5) ◽  
pp. 332-332
Author(s):  
Yongyi Li ◽  
Lev Vernik ◽  
Mark Chapman ◽  
Joel Sarout
Keyword(s):  
Reservoir Characterization ◽  
Model Building ◽  
Seismic Analysis ◽  
Focal Point ◽  
Special Section ◽  
Rock Physics ◽  
Seismic Inversion ◽  
Reservoir Properties ◽  
Model Studies ◽  
Experimental Rock

Rock physics links the physical properties of rocks to geophysical and petrophysical observations and, in the process, serves as a focal point in many exploration and reservoir characterization studies. Today, the field of rock physics and seismic petrophysics embraces new directions with diverse applications in estimating static and dynamic reservoir properties through time-variant mechanical, thermal, chemical, and geologic processes. Integration with new digital and computing technologies is gradually gaining traction. The use of rock physics in seismic imaging, prestack seismic analysis, seismic inversion, and geomechanical model building also contributes to the increase in rock-physics influence. This special section highlights current rock-physics research and practices in several key areas, namely experimental rock physics, rock-physics theory and model studies, and the use of rock physics in reservoir characterizations.

scholarly journals Generating a Cancellable Fingerprint using Matrices Operations and Its Fingerprint Processing Requirements

2018 ◽  
Vol 14 (6) ◽  
pp. 1 ◽  
Author(s):  
Riki Mukhaiyar
Keyword(s):  
Region Of Interest ◽  
Original Form ◽  
Biometric Data ◽  
Matrix Operations ◽  
The Matrix ◽  
Robust Image ◽  
Reciprocal Matrix ◽  
Processing Steps ◽  
Fingerprint Feature

Cancellable fingerprint uses transformed or intentionally distorted biometric data instead of the original biometric data for identifying person. When a set of biometric data is found to be compromised, they can be discarded, and a new set of biometric data can be regenerated. This initial principal is identical with a non-invertible concept in matrices operations. In matrix domain, a matrix cannot be transformed into its original form if it meets several requirements such as non-square form matrix, consist of one zero row/column, and no row as multiple of another row. These conditions can be acquired by implementing three matrix operations using Kronecker Product (KP) operation, Elementary Row Operation (ERO), and Inverse Matrix (INV) operation. KP is useful to produce a non-square form matrix, to enlarge the size of matrix, to distinguish and disguise the element of matrix by multiplying each of elements of the matrix with a particular matrix. ERO can be defined as multiplication and addition force to matrix rows. INV is utilized to transform one matrix to another one with a different element or form as a reciprocal matrix of the original. These three matrix operations should be implemented together in generating the cancellable feature to robust image. So, if once three conditions are met by imposter, it is impossible to find the original image of the fingerprint. The initial aim of these operations is to camouflage the original look of the fingerprint feature into an abstract-look to deceive an un-authorized personal using the fingerprint irresponsibly. In this research, several fingerprint processing steps such as fingerprint pre-processing, core-point identification, region of interest, minutiae extration, etc; are determined to improve the quality of the cancellable feature. Three different databases i.e. FVC2002, FVC2004, and BRC are utilized in this work.

Frequency-dependent seismic analysis: Data processing, modeling, and interpretation

2019 ◽  
Vol 38 (7) ◽  
pp. 556-557
Author(s):  
Yi Shen ◽  
Kui Bao ◽  
Doug Foster ◽  
Dhananjay Kumar ◽  
Kris Innanen ◽  
...  
Keyword(s):  
Model Building ◽  
Seismic Analysis ◽  
Rock Physics ◽  
Analysis Data ◽  
Seismic Interpretation ◽  
Seismic Attenuation ◽  
Frequency Dependent ◽  
University Of Texas ◽  
Q Model ◽  
Physics Modeling

A one-day postconvention workshop held during the 2018 SEG Annual Meeting in Anaheim, California, focused on seismic attenuation model building and compensation through imaging in the morning and on frequency-dependent seismic interpretation and rock physics in the afternoon. The workshop was organized by Dhananjay Kumar (BP), Yi Shen (Shell), Kui Bao (Shell), Mark Chapman (University of Edinburgh), Doug Foster (The University of Texas at Austin), Wenyi Hu (Advanced Geophysical Tech Inc.), and Tieyuan Zhu (Pennsylvania State University). The main topics discussed were: attenuation and Q model building using seismic, vertical seismic profiling, well-log and core data, seismic attenuation compensation, rock-physics modeling, seismic modeling, and frequency-dependent seismic interpretation.

Protein phasing at non-atomic resolution by combining Patterson andVLDtechniques

2014 ◽  
Vol 70 (7) ◽  
pp. 1994-2006 ◽  
Author(s):  
Rocco Caliandro ◽  
Benedetta Carrozzini ◽  
Giovanni Luca Cascarano ◽  
Giuliana Comunale ◽  
Carmelo Giacovazzo ◽  
...  
Keyword(s):  
Model Building ◽  
Protein Structures ◽  
Experimental Information ◽  
Atomic Resolution ◽  
Data Sets ◽  
Density Maps ◽  
Combined Use ◽  
Final Electron ◽  
Automatic Model Building

Phasing proteins at non-atomic resolution is still a challenge for anyab initiomethod. A variety of algorithms [Patterson deconvolution, superposition techniques, a cross-correlation function (Cmap), theVLD(vive la difference) approach, the FF function, a nonlinear iterative peak-clipping algorithm (SNIP) for defining the background of a map and thefree lunchextrapolation method] have been combined to overcome the lack of experimental information at non-atomic resolution. The method has been applied to a large number of protein diffraction data sets with resolutions varying from atomic to 2.1 Å, with the condition that S or heavier atoms are present in the protein structure. The applications include the use ofARP/wARPto check the quality of the final electron-density maps in an objective way. The results show that resolution is still the maximum obstacle to protein phasing, but also suggest that the solution of protein structures at 2.1 Å resolution is a feasible, even if still an exceptional, task for the combined set of algorithms implemented in the phasing program. The approach described here is more efficient than the previously described procedures:e.g.the combined use of the algorithms mentioned above is frequently able to provide phases of sufficiently high quality to allow automatic model building. The method is implemented in the current version ofSIR2014.

The Shock-Absorbing Quality of Rubber

1935 ◽  
Vol 8 (4) ◽  
pp. 528-547
Author(s):  
L. Frumkin ◽  
V. Margaritov
Keyword(s):  
Shock Loading ◽  
Shock Absorber ◽  
Static Load ◽  
Original Form ◽  
Steel Spring ◽  
Easy Calculation ◽  
Absorbing Material ◽  
The Difference ◽  
The Impact

Abstract The extensive use of rubber as a shock-absorbing and vibration-absorbing material makes necessary a definite criterion for this property of rubber. In his work on the problem of the shock-absorbing quality of rubber, Morrison states: “To make possible an easy calculation of the rubber buffer, it is necessary to know (1) the permissible working strain at the static loading for a given rubber, (2) the maximum strain permissible at the shock loading, and (3) the energy absorbed by a unit volume of rubber in tile transition from static to shock loading.” Reference to static load is made because, in this calculation, it is necessary to consider those static forces which act on the rubber before shock. The energy absorbed by the rubber in the transition from the static to the shock load is supposed by Morrison to be that energy which is absorbed by the rubber in its deformation by the shock. The question of the energy returned by the rubber in resuming its original form is not considered by him. Vetchinkin in his study of the work of shock-absorbing aeroplane cords fails also to take into consideration the energy returned by the cord on resuming its original form, and bases his calculation only on the absorption by the rubber of a definite quantity of energy during stretching caused by the impact of the aeroplane against the ground. He mentions only casually that, by increasing the preliminary tautness of tile cords, their hysteresis losses of energy are increased. However, such a concept of the work of a rubber shock-absorber seem to us inadequate. In fact, let us distinguish clearly between the work of shock-absorption of rubber and a steel spring. Of course it should be noted that for deformations by the highest possible stresses for rubber and for a steel spring, the former requires more energy per unit of weight. Thus, according to the above quoted paper by Morrison, 1 kg. of rubber absorbs 172 kg. of energy and 1 kg. of steel only 119 kg., i.e., 44% less. According to Geer (cf. “The Reign of Rubber” the difference is many times greater, viz., 10,000 kg. for rubber and 230 kg. for steel.

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