Borehole dc resistivity response for a transitional invaded zone

Geophysics ◽  
1994 ◽  
Vol 59 (12) ◽  
pp. 1796-1805 ◽  
Author(s):  
K. K. Roy ◽  
D. J. Dutta
Keyword(s):  
Separation Of Variables ◽  
Electrode Array ◽  
Forward Model ◽  
Scale Model ◽  
Model Data ◽  
Mud Cake ◽  
Alternative Approach ◽  
Data Points ◽  
Invaded Zone ◽  
D Model

A borehole direct‐current resistivity boundary value problem for normal and lateral elctrode configuratin is soved assuming axial symmetry. The borehole mud, a flushed zone, an invaded zone, and an unciontaminated zone are all assumed to be present. A linear transition in resistivity is assumed for the invaded zone. Frobenius extended power series and the method of separation of variables are used to solved the 1-D problem. Single-run borehole resistivity sounding and solution of the inverse problem are suggested fo estimatingthe resisitivity of the uncontaminated zone and the radius of invasion. Finite‐difference modeling is dione to estimate the effect of shoulder beds ion borehole sounding. Some of the computed 1-D and 2-D model apparent reisivity curves are compared with the existing scale model data. The analysis reveals that the mud cake effect is negligible for normal and lateral electrode array and the invasion zone thickness is feflected in the forward models. Apparent resistivity curves with and without a transitional invaded zone are well separated. Resistivity departure curves are well separated for fixed resistivity and variable resistivity invaded zone models. A normal electrode configuration can feel the presence of the shoulder bed in a 2-D model when the bed thickness is about 12 time the electrode separation. One‐dimensional ridge regression inversion the synthetic forward model data is presented to suggest an alternative approach for determining the resistivey of the uncontaminated zone ([Formula: see text]) and the radius of invasion [Formula: see text]. We conclude that (1) a single run borehole sounding with 10 or 12 data points from a normal or lateral log may be used, rather than 3 points from a dual laterolog [Formula: see text] tool, for better estimation of [Formula: see text], and (2) a borehole forward model should include a transitional invaded zone. Finally, an alternative approach for the estimation of the radius of invasion is proposed.

scholarly journals Constraining a complex biogeochemical model for CO<sub>2</sub> and N<sub>2</sub>O emission simulations from various land uses by model–data fusion

2017 ◽  
Vol 14 (14) ◽  
pp. 3487-3508 ◽  
Author(s):  
Tobias Houska ◽  
David Kraus ◽  
Ralf Kiese ◽  
Lutz Breuer
Keyword(s):  
Data Fusion ◽  
Arable Land ◽  
Shallow Groundwater ◽  
Scale Model ◽  
Biogeochemical Model ◽  
N2o Emissions ◽  
Model Errors ◽  
Model Data ◽  
Validation Data ◽  
Fusion Concept

Abstract. This study presents the results of a combined measurement and modelling strategy to analyse N2O and CO2 emissions from adjacent arable land, forest and grassland sites in Hesse, Germany. The measured emissions reveal seasonal patterns and management effects, including fertilizer application, tillage, harvest and grazing. The measured annual N2O fluxes are 4.5, 0.4 and 0.1 kg N ha−1 a−1, and the CO2 fluxes are 20.0, 12.2 and 3.0 t C ha−1 a−1 for the arable land, grassland and forest sites, respectively. An innovative model–data fusion concept based on a multicriteria evaluation (soil moisture at different depths, yield, CO2 and N2O emissions) is used to rigorously test the LandscapeDNDC biogeochemical model. The model is run in a Latin-hypercube-based uncertainty analysis framework to constrain model parameter uncertainty and derive behavioural model runs. The results indicate that the model is generally capable of predicting trace gas emissions, as evaluated with RMSE as the objective function. The model shows a reasonable performance in simulating the ecosystem C and N balances. The model–data fusion concept helps to detect remaining model errors, such as missing (e.g. freeze–thaw cycling) or incomplete model processes (e.g. respiration rates after harvest). This concept further elucidates the identification of missing model input sources (e.g. the uptake of N through shallow groundwater on grassland during the vegetation period) and uncertainty in the measured validation data (e.g. forest N2O emissions in winter months). Guidance is provided to improve the model structure and field measurements to further advance landscape-scale model predictions.

Skin Friction Resistance of Ships

1957 ◽  
Vol 1 (03) ◽  
pp. 3-12
Author(s):  
F. H. Todd
Keyword(s):  
Skin Friction ◽  
Present Status ◽  
Comparative Studies ◽  
Scale Model ◽  
Small Scale ◽  
Model Data ◽  
Towing Tank ◽  
Friction Resistance ◽  
Small Scale Model

The International Towing Tank Conference (ITTC) is to hold its 8th meeting in Madrid in September of this year. One of the subjects to be discussed will be the perennial one of how to estimate the resistance of a ship from that measured on a small-scale model in a towing tank. The Skin Friction Committee of the Conference was charged at the last meeting in Scandinavia in 1954, with reviewing the available data and making recommendations to the Conference in Madrid which will, it is hoped, be universally acceptable. Such a decision would remove one of the principal difficulties experienced in the use of model data in comparative studies. It is believed that a review of the present status of our knowledge in this field may be of interest to the members of the Society at this time.

Gaussian Processes for Hydrocarbon Depth Estimation in Forward Modeling of Seabed Logging

2019 ◽  
Vol 24 (3) ◽  
pp. 399-408
Author(s):  
Muhammad Naeim Mohd Aris ◽  
Hanita Daud ◽  
Sarat Chandra Dass ◽  
Khairul Arifin Mohd Noh
Keyword(s):  
Electric Field ◽  
Gaussian Processes ◽  
Depth Estimation ◽  
Forward Modeling ◽  
Hydrocarbon Reservoir ◽  
Offset Distance ◽  
Data Points ◽  
Gp Model ◽  
D Model ◽  
True Values

Seabed logging (SBL) is an application of the marine controlled-source electromagnetic (CSEM) technique to discover offshore hydrocarbon reservoirs underneath the seabed. This application is based on electrical resistivity contrast between hydrocarbon and its surroundings. In this paper, simulation and forward modeling were performed to estimate the hydrocarbon depths in one-dimensional (1-D) SBL data. 1-D data, consisted offset distance (input) and magnitude of electric field (output), were acquired from SBL models developed using computer simulation technology (CST) software. The computer simulated outputs were observed at various depths of hydrocarbon reservoir (250 m–2,750 m with an increment of 250 m) with frequency of 0.125 Hz. Gaussian processes (GP) was employed in the forward modeling by utilizing prior information which is electric field (E-field) at all observed inputs to provide E-field profile at unobserved/untried inputs with uncertainty quantification in terms of variance. The concept was extended for two-dimensional (2-D) model. All observations of E-field were then investigated with the 2-D forward GP model. Root mean square error (RMSE) and coefficient of variation (CV) were utilized to compare the acquired and modeled data at random untried hydrocarbon depths at 400 m, 950 m, 1,450 m, 2,100 m and 2,600 m. Small RMSE and CV values have indicated that developed model can fit well the SBL data at untried hydrocarbon depths. The measured variances of the untried inputs revealed that the data points (true values) were very close to the estimated values, which was 0.003 (in average). RMSEs obtained were very small as an average of 0.049, and CVs found as very reliable percentages, an average of 0.914%, which implied well fitting of the GP model. Hence, the 2-D forward GP model is believed to be capable of predicting unobserved hydrocarbon depths.

Use of Scale-Model Aids in Solution of Complex Air-Flow Design Problem

1965 ◽  
Author(s):  
Arthur Oppenheim ◽  
Frederic M. Oran
Keyword(s):  
Scale Construction ◽  
Scale Model ◽  
Inlet Section ◽  
Engine Test ◽  
Model Data ◽  
Jet Engine ◽  
Basic Fluid ◽  
Air Stream ◽  
Step Procedure ◽  
Selection Of

This paper describes a method used to design the inlet section of a jet-engine test cell. Calculations, accomplished with the use of standard, tabulated flow formulas and coefficients which can be found in basic fluid-flow texts, are shown. The step-by-step procedure enables the reader to use the methods and formulas in this paper as a guide for solving similar problems. Selection of an optimum turning-vane configuration is described herein by the use of tufts of cotton in the air stream of the model. A table is included which compares the model data with actual full-scale construction at various stages.

Acoustic modeling and migration of stacked cross‐hole data

Geophysics ◽  
1988 ◽  
Vol 53 (4) ◽  
pp. 492-500 ◽  
Author(s):  
Xianhuai Zhu ◽  
George A. McMechan
Keyword(s):  
Line Source ◽  
Synthetic Data ◽  
Point Sources ◽  
Scale Model ◽  
Model Data ◽  
Reverse Time ◽  
Imaging Condition ◽  
Surface Survey ◽  
Excitation Time ◽  
And Migration

Prestack computations for cross‐hole data are relatively expensive, as they are for prestack surface survey data. It is therefore of interest to develop methodologies for modeling and processing stacked cross‐hole data. In this context, stacking is over sources, not midpoints. Modeling with a line source produces data that are equivalent (by Huygen’s principle) to those obtained by stacking over a line of point sources. Reverse‐time finite‐difference migration may be applied to the resulting stacked section by generalizing the excitation‐ time imaging condition for a point source to a line source. Illustrations include successful applications to both synthetic data and scale‐model data.

scholarly journals Resilience of Student Viewed from Gender, Culture Background and Attachment of parents and Implication in Guidance and Counseling

10.32698/0522 ◽  
2018 ◽  
Vol 1 (1) ◽  
pp. 44
Author(s):  
Vasco Delano ◽  
Daharnis Daharnis ◽  
Yeni Karneli
Keyword(s):  
Random Sampling ◽  
Cultural Background ◽  
Likert Scale ◽  
Quantitative Approach ◽  
Scale Model ◽  
Guidance And Counseling ◽  
Model Data ◽  
Gender Culture ◽  
Descriptive Method ◽  
Anova Technique

Resilience by disaster need to be grown in individual’s self in order that does not become problem in the development of individual to become a better person. Many factors affect resilience, including gender, cultural background and attachment of parents. This study aims to test the relevancy of resilience with several factors. This research uses quantitative approach with comparative descriptive method. The population  is 912 students with a sample amounts 278 students with using Proportional Random Sampling. The instrument used is Likert scale model. Data were analyzed by three way ANOVA technique. The results showed that gender and attachment of parents affect individual’s resilience while culture significantly has no relevance resilience. The implications of this research will be discussed.

scholarly journals Comparison of observed borehole temperatures in Antarctica with simulations using a forward model driven by climate model outputs covering the past millennium

2020 ◽  
Author(s):  
Zhiqiang Lyu ◽  
Anais J. Orsi ◽  
Hugues Goosse
Keyword(s):  
Surface Temperature ◽  
Antarctic Peninsula ◽  
Time Domain ◽  
Climate Model ◽  
Forward Model ◽  
Model Data ◽  
West Antarctica ◽  
Data Comparison ◽  
Borehole Temperature ◽  
The Time Domain

Abstract. The reconstructed surface temperature series from boreholes in Antarctica have significantly contributed to our understanding of centennial and multi-decadal temperature changes and thus provides us a good way to evaluate the climate model ability to reproduce low-frequency climate variability. However, up to now, there were no systematic model-data comparisons based on temperature from boreholes at regional or local scale in Antarctica. Here, we discuss two different ways to perform such a comparison using boreholes measurements and the corresponding reconstructions of surface temperature at West Antarctic Ice Sheet (WAIS), Larissa, Mill Island and Styx in Antarctica. The standard approach is to compare climate model outputs at the grid point closest to each site with the reconstructions in the time domain derived from the direct borehole temperature observations. Although some characteristics of the reconstructions, for instance the non-uniform smoothing, limit to some extent the model-data comparison, several robust features can be evaluated. In addition, a more direct model-data comparison based on the temperature measured in the boreholes is conducted using a forward model that simulates explicitly the subsurface temperature profiles when driven with climate model outputs. This comparison in the depth domain provides many consistent signals with those in the time domain, but also suggest some information that we cannot extract from the comparison in the time domain. The major results from these comparisons are used to define some metrics derived from the borehole temperature data for future model-data comparison, and demonstrate the spatial representativity of the sites chosen for the metrics. The long term cooling trend in West Antarctica from 1000 to 1600 CE (−1.0 °C) is generally reproduced by the models, but often with a weaker amplitude. The 19th century cooling in the Antarctic Peninsula (−0.94 °C) is not reproduced by any of the models, which tend to show warming instead. The trend over the last 50 years is generally well reproduced in West Antarctica and at Larissa (Antarctic Peninsula), but overestimated at other sites. The wide range of simulated trends indicates the importance of internal variability on the observed trends, and show the value of model-data comparison to investigate the response to forcings.

scholarly journals Kontribusi Media Pembelajaran Daring terhadap Minat Belajar Siswa

2021 ◽  
pp. 76-81
Author(s):  
Nazyumei Arbah ◽  
Rini Sefriani ◽  
Astri Indah Juwita
Keyword(s):  
Online Learning ◽  
Data Analysis ◽  
Data Collection ◽  
Random Sampling ◽  
Sampling Technique ◽  
Scale Model ◽  
Student Interest ◽  
Model Data ◽  
Microsoft Excel ◽  
Network Service

This study aims to determine the contribution of online learning media to students' interest in learning in network service technology subjects for class XI Smk Negeri 8 Padang. The type of this research is correlational quantitative, the sampling is done using the Proportion Random Sampling technique. Total 66 people. The instrument used in data collection in this study was a questionnaire compiled according to the Likert scale model. Data analysis was performed using SPSS 20 and Microsoft Excel. Based on the results of the study, the value of rcount -0.212 while the value of rtable is 0.250 because the value of rcount is smaller than the value of rtable is 0.212 < 0.250) it can be concluded that there is no significant relationship between online learning media and student interest in learning, with a contribution value of 4.5% which means that online learning contributes to students' interest in learning in network service technology subjects is very low. which means that online learning contributes to students' interest in learning in network service technology subjects is very low.

Sign in / Sign up

Export Citation Format

Share Document