scholarly journals EFFECTS OF THE DEVIATION ANGLE OF THE BOREHOLE IN THE INDUCTION ANISOTROPY LOGS

2018 ◽  
Vol 36 (4) ◽  
pp. 1
Author(s):  
Paulo Roberto de Carvalho ◽  
Cícero Régis ◽  
Valdelírio da Silva e Silva
Keyword(s):  
Well Logging ◽  
Deviation Angle ◽  
Vertical Wells ◽  
One Dimensional ◽  
Anisotropic Models ◽  
Coil Arrays ◽  
Complex Models ◽  
Dip Angle ◽  
Basic Insight ◽  
Vertical Case

ABSTRACT. This paper performs an analysis of the effects of the well’s deviated angle on the tensor triaxial induction tool signals within a thinly sand-shale laminated reservoirs and their equivalent intrinsic anisotropic models. The responses from coaxial and coplanar coil arrays in inclined wells are studied in detail, including the analysis of their apparent anisotropy logs, as well as their estimation of sand conductivity in the environments with a structural anisotropy.The dip angle effects are modeled in simple geometries as one-dimensional (1D) models, neglecting the presence of the borehole and the invasion zones, since they provide basic insight for understanding tool responses in more complex models. The results show a strong sensitivity of both the coaxial and coplanar signals to the deviated angle. It is verified that the anisotropy values are significantly reduced when the well is inclined as compared to what is found for the true vertical case, even for inclinations small enough for the wells to be classified as technically vertical (30 degrees or less). Therefore, the angle effects must be carefully considered, even for technically vertical wells. Otherwise, potential finely laminated reservoirs can be underestimated or even ignored.Keywords: deviated well logging, tensor induction tool, laminated reservoirs, electrical anisotropy.RESUMO. Neste trabalho é apresentado como as incertezas na interpretação sísmica impactam na cons-trução do modelo de velocidades e na conversão tempo-profundidade resultante. A área de estudo de estudo está localizada na Bacia de Campos, Brasil. O principal objetivo deste trabalho é mostrar como os dados de entrada e parâmetros afetam na modelagem de velocidade e conversão tempo x profundidade. A metodologia é comparar três diferentes cenários para calibração da velocidade de processamento e imageamento com as interpretações sísmicas e de poços: o cenário 1 utiliza ajuste por horizonte com marcador geológico e raio de influência 5 km; no cenário 2 é utilizada as tabelas tempo-profundidade, raio de influência 5 km por krigagem com derivada externa; e o cenário 3 utilizou-se tabelas tempo-profundidade, raio de influência 2 km por krigagem com deriva externa. O controle de qualidade dos três modelos de velocidade são avaliados pela conversão dos horizontes, seções sísmicas e perfis de pseudo-impedância. No cenário 1, os horizontes convertidos apresentam menores diferenças de profundidade em relação aos marcadores comparados aos demais cenários. Por outro lado, os cenários 2 e 3 apresentam maiores correlações entre o sismograma sintético e a seção sísmica convertida para o cenário 1. Palavras-chave: poços desviados, ferramentas triaxiais, reservatórios laminados, anisotropia elétrica.

Singular value decomposition for cross‐well tomography

Geophysics ◽  
1993 ◽  
Vol 58 (11) ◽  
pp. 1655-1661 ◽  
Author(s):  
Reinaldo J. Michelena
Keyword(s):  
Singular Value Decomposition ◽  
Null Space ◽  
Vertical Component ◽  
Singular Values ◽  
Singular Value ◽  
Velocity Estimation ◽  
One Dimensional ◽  
Anisotropic Models ◽  
Value Decomposition ◽  
Frequency Variations

I perform singular value decomposition (SVD) on the matrices that result in tomographic velocity estimation from cross‐well traveltimes in isotropic and anisotropic media. The slowness model is parameterized in four ways: One‐dimensional (1-D) isotropic, 1-D anisotropic, two‐dimensional (2-D) isotropic, and 2-D anisotropic. The singular value distribution is different for the different parameterizations. One‐dimensional isotropic models can be resolved well but the resolution of the data is poor. One‐dimensional anisotropic models can also be resolved well except for some variations in the vertical component of the slowness that are not sensitive to the data. In 2-D isotropic models, “pure” lateral variations are not sensitive to the data, and when anisotropy is introduced, the result is that the horizontal and vertical component of the slowness cannot be estimated with the same spatial resolution because the null space is mostly related to horizontal and high frequency variations in the vertical component of the slowness. Since the distribution of singular values varies depending on the parametrization used, the effect of conventional regularization procedures in the final solution may also vary. When the model is isotropic, regularization translates into smoothness, and when the model is anisotropic regularization not only smooths but may also alter the anisotropy in the solution.

scholarly journals A New Approach for Accurate Prediction of Liquid Loading of Directional Gas Wells in Transition Flow or Turbulent Flow

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Ruiqing Ming ◽  
Huiqun He
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Correction Coefficient ◽  
Calculation Error ◽  
Gas Velocity ◽  
Transition Flow ◽  
Deviation Angle ◽  
Vertical Wells ◽  
Liquid Loading ◽  
New Model

Current common models for calculating continuous liquid-carrying critical gas velocity are established based on vertical wells and laminar flow without considering the influence of deviation angle and Reynolds number on liquid-carrying. With the increase of the directional well in transition flow or turbulent flow, the current common models cannot accurately predict the critical gas velocity of these wells. So we built a new model to predict continuous liquid-carrying critical gas velocity for directional well in transition flow or turbulent flow. It is shown from sensitivity analysis that the correction coefficient is mainly influenced by Reynolds number and deviation angle. With the increase of Reynolds number, the critical liquid-carrying gas velocity increases first and then decreases. And with the increase of deviation angle, the critical liquid-carrying gas velocity gradually decreases. It is indicated from the case calculation analysis that the calculation error of this new model is less than 10%, where accuracy is much higher than those of current common models. It is demonstrated that the continuous liquid-carrying critical gas velocity of directional well in transition flow or turbulent flow can be predicted accurately by using this new model.

Optimal Design of Sandwich Beam With Frequency Constraints

2007 ◽  
Author(s):  
Vladimir B. Gantovnik ◽  
Alexander V. Lopatin ◽  
Lubov V. Shumkova
Keyword(s):  
Equations Of Motion ◽  
Sandwich Beam ◽  
Vibrational Analysis ◽  
Optimal Parameters ◽  
One Dimensional ◽  
Sandwich Plates And Shells ◽  
Complex Models ◽  
Plates And Shells ◽  
Transversal Vibrations ◽  
Selection Of

In this paper, we analyze selection of optimal parameters of sandwich beam in the presence of constraints on the frequencies of the transversal vibrations. The employed equations of motion take into account the transverse shear deformations in the core and rotatory inertia of the beam cross-section. The expressions for the transversal vibrations are obtained. The results show that one-dimensional model of the sandwich beam can be used for preliminary vibrational analysis of more complex models of sandwich plates and shells.

scholarly journals Getting started with controlled-source electromagnetic 1D modeling

2017 ◽  
Vol 36 (4) ◽  
pp. 352-355 ◽  
Author(s):  
Dieter Werthmüller
Keyword(s):  
Forward Modeling ◽  
Higher Dimensions ◽  
Hydrocarbon Exploration ◽  
Fine Scale ◽  
One Dimensional ◽  
Controlled Source ◽  
1D Modeling ◽  
Resistivity Anisotropy ◽  
Complex Models ◽  
Diffusive Term

Forward modeling is an important part of understanding controlled-source electromagnetic (CSEM) responses. The diffusive term in the electromagnetic wave equation is dominant over the displacement term at these frequencies. It is the diffusive behavior that makes it difficult to imagine the actual propagation of the signal. An important tool in gaining experience therefore is forward modeling, and lots of it. The advantage of one-dimensional (1D) forward modeling, besides its speed, is to study isolated effects (see for instance Key, 2009): What is the influence of resistivity anisotropy, or of fine-scale resistivity variations? What is the influence of the airwave? With 1D modeling you can quickly study these effects in isolation before you go on to more complex models in higher dimensions. For an introduction to CSEM for hydrocarbon exploration see, for instance, Constable (2010).

scholarly journals A numerical model to investigate the polarisation azimuth of ULF waves through an ionosphere with oblique magnetic fields

2005 ◽  
Vol 23 (11) ◽  
pp. 3457-3471 ◽  
Author(s):  
M. D. Sciffer ◽  
C. L. Waters ◽  
F. W. Menk
Keyword(s):  
Magnetic Fields ◽  
Low Frequency ◽  
Wave Mode ◽  
Ulf Waves ◽  
High Latitudes ◽  
Wave Fields ◽  
One Dimensional ◽  
Ulf Wave ◽  
Dip Angle ◽  
Ground Wave

Abstract. A one dimensional, computational model for the propagation of ultra low frequency (ULF; 1-100 mHz) wave fields from the Earth's magnetosphere through the ionosphere, atmosphere and into the ground is presented. The model is formulated to include solutions for high latitudes where the Earth's magnetic field, (B0), is near vertical and for oblique magnetic fields applicable at lower latitudes. The model is used to investigate the wave polarisation azimuth in the magnetosphere compared with the ground wave fields, as a function of the dip angle of B0. We find that for typical ULF wave scale sizes, a 90° rotation of the wave polarisation azimuth from the magnetosphere to the ground occurs at high latitudes. However, this effect does not necessarily occur at lower latitudes in all cases. We show that the degree to which the wave polarisation azimuth rotates critically depends on the properties of the compressional ULF wave mode.

scholarly journals Stochastic Hydrology: Is Scientific Understanding Growing?

2020 ◽  
Vol 163 ◽  
pp. 06001
Author(s):  
Mikhail Bolgov
Keyword(s):  
Climate Changes ◽  
Probability Distributions ◽  
Random Processes ◽  
Stochastic Hydrology ◽  
One Dimensional ◽  
Probabilistic Forecasts ◽  
Markovian Property ◽  
New Models ◽  
Complex Models ◽  
With Memory

Among many problems of stochastic hydrology, several major problems may be singled out. (1) The methodology problem – may fluctuation of hydro-meteorological values be considered within the framework of probabilities and random processes? Was this topic discussed after 1953? (2) One-dimensional probability distributions – is there progress? Are there new models? (3) Random Processes: Is Markovian property sufficient or more complex models with memory are needed? (4) Lack of stability resulting from climate changes: Is there progress in understanding the approaches to probabilistic forecasts?

scholarly journals A collection of programs for one-dimensional Ising analysis of linear repeat proteins with point substitutions

2020 ◽  
Author(s):  
Jacob D. Marold ◽  
Kevin Sforza ◽  
Kathryn Geiger-Schuller ◽  
Tural Aksel ◽  
Sean Klein ◽  
...  
Keyword(s):  
Parameter Uncertainty ◽  
Free Energies ◽  
Interfacial Coupling ◽  
Bootstrap Analysis ◽  
One Dimensional ◽  
Repeat Proteins ◽  
Rigorous Statistical Analysis ◽  
Estimate Parameter ◽  
Rigorous Framework ◽  
Complex Models

AbstractA collection of programs is presented to analyze the thermodynamics of folding of linear repeat proteins using a 1D Ising model to determine intrinsic folding and interfacial coupling free energies. Expressions for folding transitions are generated for a series of constructs with different repeat numbers and are globally fitted to transitions for these constructs. These programs are designed to analyze Ising parameters for capped homopolymeric consensus repeat constructs as well as heteropolymeric constructs that contain point substitutions, providing a rigorous framework for analysis of the effects of mutation on intrinsic and directional (i.e., N- versus C-terminal) interfacial coupling free-energies. A bootstrap analysis is provided to estimate parameter uncertainty as well as correlations among fitted parameters. Rigorous statistical analysis is essential for interpreting fits using the complex models required for Ising analysis of repeat proteins, especially heteropolymeric repeat proteins. Programs described here are available at https://github.com/barricklab-at-jhu/Ising_programs.

scholarly journals REVISITING SOME OLD UNEXPLAINED EFFECTS IN INDUCTION LOGS WITHIN LAMINATED FORMATIONS WITH THE TRIAXIAL INDUCTION TOOL

2016 ◽  
Vol 34 (3) ◽  
Author(s):  
Paulo Roberto De Carvalho ◽  
Cícero Roberto Teixeira Régis
Keyword(s):  
Electrical Resistivity ◽  
Well Logging ◽  
Electrical Anisotropy ◽  
One Dimensional ◽  
Resistivity Anisotropy ◽  
Induction Logs

ABSTRACT. Modern induction triaxial or multicomponent well logging tools provide resistivity anisotropy logs, and estimates of the electrical resistivity of sand laminae in thinly laminated formations. In this paper, coaxial and coplanar vertical logs were modeled in one-dimensional (1D) laminated packages and in their equivalent anisotropic beds, neglecting the presence of the borehole and the invasion...Keywords: well logging, multicomponent induction tool, laminated reservoirs, electrical anisotropy. RESUMO. As atuais ferramentas de perfilagem em poço por indução eletromagnética, denominadas triaxias ou multicomponentes, fornecem perfis de anisotropia elétrica e permitem estimar a resistividade de lâminas de areia em ambientes finamente laminados. Neste artigo, os perfis dos arranjos coaxial e coplanar de bobinas foram simulados em modelos...Palavras-chave: perfilagem de poço, ferramentas multicomponetes, reservatórios laminados, anisotropia elétrica.

Wellbore Stability of Shale below Salt Formation of Faqui Oilfield in Iraq

2014 ◽  
Vol 641-642 ◽  
pp. 451-457
Author(s):  
Fan Zhang ◽  
Yun Long Mu ◽  
Shuang Cheng ◽  
Jin Gen Deng ◽  
Bao Hua Yu ◽  
...  
Keyword(s):  
Strength Criterion ◽  
Wellbore Stability ◽  
Experimental Results ◽  
Salt Formation ◽  
Deviation Angle ◽  
Collapse Pressure ◽  
Stress Orientations ◽  
Dip Angle ◽  
High Degree ◽  
Coulomb Criterion

Serious borehole collapse has occurred in shale below salt formation of Fauqi oilfield in Iraq. The Lots of bedding shale cavings returned to ground. The strength of bedding shale cores with different bedding dip angle are tested, which changes along in a high degree with the dip angle and reach the minimum in 50°-60°. The experimental results are regressed by different strength criterion, which demonstrate that McLamore strength criterion is more accurate. The collapse pressure of shale below salt formation is calculated by Mohr-Coulomb criterion and McLamore criterion respectively. The maximum collapse pressure by Mohr-Coulomb criterion occurs in the maximum in-stress orientations and 90° deviation angle, and that by McLamore criterion occurs in the maximum in-stress orientations and 50°-60° deviation angle. By analyzing the actual drilling situation, McLamore criterion is proved to be more accurate and can be used in Fauqi oilfield.

Domestic rotary steerable systems development potential for drilling horizontal wells

2020 ◽  
pp. 74-80
Author(s):  
V. V. Saltykov ◽  
Yu. S. Makovsky ◽  
M. M. Mansurova
Keyword(s):  
Horizontal Wells ◽  
Systems Development ◽  
Oil Field ◽  
High Tech ◽  
Technological Solution ◽  
Deviation Angle ◽  
Vertical Wells ◽  
Special Equipment ◽  
The Past

A complex of special equipment is required for the construction of high-tech wells. The basis of modern time efficient, precise and safe drilling is rotary steerable systems (RSS). For the past five years, rotary steerable systems have been using in Russia as a technical and technological solution to reduce accidents and to improve the quality of well construction with large vertical deviations of the extended drilling radius. These systems allow drilling to be oriented along the entire length of the well. Rotary steerable systems allows drilling both perfectly vertical wells with a deviation angle of not more than 0,2°, and horizontal wells more than 2 000 metres long. Implementation of rotary steerable systems allows building wells with extremely extended reach and conducting wells in 1–2 metres thick reservoirs with precision. In 2016, OktoGeo LLC carried out pilot well program with APS Technology's 172 mm RSS (with power section) at an oil field in the territory of KhantyMansiysk Autonomous Okrug — Ugra. All the rotary steerable system positioning programs were completed based on the results of that work and results of drilling 2 205 metres long directional well.

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