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Analysis of Well log Data Using Detrended Fluctuation Analysis and its Comparison with Other Methods (Multifractal Analysis of Well Log Data)
, M.Sc. Thesis Sharif University of Technology ; Sahimi, Mohammad (Supervisor) ; Massihi, Mohsen (Supervisor) ; Jafari, Gholam Reza (Supervisor)
Abstract
One of the main challenges in characterization and simulation of larg scale porous media is spatial heterogeneity and variability of porous media properties such as porosity, density, and lithology at different scales. These information can be achieved at different scale from coring, well logging or seismic data. Well logs are an efficient way to obtain rock and fluid properties of geological patterns specially water resources and hydrocarbon reservoirs. One of the characteristics of geophysical well logs is their complex behavior which seems to imply a multifractal nature.In this study we investigate multifractality and presence of long range correlations in petrophysical well log data such...
The estimation of formation permeability in a carbonate reservoir using an artificial neural network
, Article Petroleum Science and Technology ; Volume 30, Issue 10 , 2012 , Pages 1021-1030 ; 10916466 (ISSN) ; Masihi, M ; Fatholahi, S ; Sharif University of Technology
2012
Abstract
Reservoir permeability is an important parameter that its reliable prediction is necessary for reservoir performance assessment and management. Although many empirical formulas are derived regarding permeability and porosity in sandstone reservoirs, these correlations cannot be accurately depicted in carbonate reservoir for the wells that are not cored and for which there are no welltest data. Therefore, having a framework for estimation of these parameters in reservoirs with neither coring samples nor welltest data is crucial. Rock properties are characterized by using different well logs. However, there is no specific petrophysical log for estimating rock permeability; thus, new methods...
Analysis of cross correlations between well logs of hydrocarbon reservoirs
, Article Transport in Porous Media ; Volume 90, Issue 2 , 2011 , Pages 445-464 ; 01693913 (ISSN) ; Jafari, G. R ; Lai, Z. K ; Masihi, M ; Sahimi, M ; Sharif University of Technology
Abstract
We carry out a series of cross-correlation analysis of raw well-log data, in order to study the possible connection between natural gamma ray (GR) logs and other types of well logs, such as neutron porosity (NPHI), sonic transient time (denoted usually by DT), and bulk density (RHOB) of oil and gas reservoirs. Three distinct, but complementary, methods are used to analyze the cross correlations, namely, the multifractal detrended cross-correlation analysis (MF-DXA), the so-called Qcc(m) test in conjunction with the statistical test-the χ2(m) distribution-and the cross-wavelet transform (XWT) and wavelet coherency. The Qcc(m) test and MF-DXA are used to identify and quantify the strength of...
Evaluation of different machine learning frameworks to predict CNL-FDC-PEF logs via hyperparameters optimization and feature selection
, Article Journal of Petroleum Science and Engineering ; Volume 208 , 2022 ; 09204105 (ISSN) ; Heidaryan, E ; Ostadhassan, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Although being expensive and time-consuming, petroleum industry still is highly reliant on well logging for data acquisition. However, with advancements in data science and AI, methods are being sought to reduce such dependency. In this study, several important well logs, CNL, FDC and PEF from ten wells are predicted based on ML models such as multilinear regression, DNN, DT, RT, GBoost, k-NN, and XGBoost. Before applying these models, depth matching, bad hole correction, de-spiking, and preprocessing of the data, including normalization, are carried out. Three statistical metrics, R2, RMSE, and PAP, are applied to evaluate the models' performance. Results showed that RF, k-NN, and XGBoost...
Scaling, multifractality, and long-range correlations in well log data of large-scale porous media
, Article Physica A: Statistical Mechanics and its Applications ; Vol. 390, issue. 11 , June , 2011 , p. 2096-2111 ; ISSN: 03784371 ; Jafari, G. R ; Sahimi, M ; Masihi, M ; Sharif University of Technology
Abstract
Three distinct methods, namely, the spectral density, the multifractal random walk approach, and the multifractal detrended fluctuation analysis are utilized to study the properties of four distinct types of well logs from three oil and gas fields, namely, the natural gamma ray emission, neutron porosity, bulk density, and the sonic transient time logs. Such well logs have never been analyzed by the methods that we utilize in the present study. The results indicate that the well logs exhibit multifractal characteristics, and the estimated Hurst exponents by the three methods are close to each other. Using multifractal detrended fluctuation analysis and the shuffled and surrogated data, we...
Scaling, multifractality, and long-range correlations in well log data of large-scale porous media
, Article Physica A: Statistical Mechanics and its Applications ; Volume 390, Issue 11 , 2011 , Pages 2096-2111 ; 03784371 (ISSN) ; Jafari, G. R ; Sahimi, M ; Masihi, M ; Sharif University of Technology
2011
Abstract
Three distinct methods, namely, the spectral density, the multifractal random walk approach, and the multifractal detrended fluctuation analysis are utilized to study the properties of four distinct types of well logs from three oil and gas fields, namely, the natural gamma ray emission, neutron porosity, bulk density, and the sonic transient time logs. Such well logs have never been analyzed by the methods that we utilize in the present study. The results indicate that the well logs exhibit multifractal characteristics, and the estimated Hurst exponents by the three methods are close to each other. Using multifractal detrended fluctuation analysis and the shuffled and surrogated data, we...
Fully Digital Implementation and Optimization of Openhole Oil Well Surface Modem
, M.Sc. Thesis Sharif University of Technology ; Movahedian, Hamid (Supervisor) ; Gholampour, Iman (Co-Supervisor)
Abstract
Once a well has been drilled before it is cased with the steels (open-hole well), some logging must be done to record information’s about layers, geologic formations, geophysical and petrophysical properties of well. All the information’s that gathered from sensors and tools transmitted to the surface by a down-hole modem. This information is corrupted during the transmission by the communication channel. The most notable influence of this channel is noise, attenuation and interference between successive data bits. On the other hand, the characteristic of channel changes with the length of the cable, temperature, connections and so on. So using a set of fixed filters is not effective. The...
Density Measurement in Oil and Gas Wells using Ultrasonic Sensors
, M.Sc. Thesis Sharif University of Technology ; Movahedian Attar, Hamid (Supervisor)
Abstract
Production logging consists of running measurement instruments called logging tools into an oil or gas well to measure various parameters such as temperature, flow velocity, pressure, density, etc. The primary purpose for production logging is to allow enhancing production profits and decreasing costs. Nowadays the common way for fluid density measurement as a part of these tools depends on radioactive source. Special considerations must be taken upon the use of this principle due to its radioactive character. This thesis is focused on a non-radioactive method of determining density. The subject of this thesis is to consider methods for measuring density based on principle of acoustic...
Application of artificial neural network for estimation of formation permeability in an iranian reservoir
, Article 1st International Petroleum Conference and Exhibition, Shiraz, 4 May 2009 through 6 May 2009 ; 2009 ; Masihi, M ; Fatholahi, S ; Sharif University of Technology
European Association of Geoscientists and Engineers, EAGE
2009
Abstract
The permeability is one of the most important reservoir parameters and its accurate prediction is necessary for reservoir management and enhancement. Although many empirical formulas are derived regarding permeability and porosity in sandstone reservoirs [1], these correlations cannot be modified accurately in carbonate reservoir for the wells which are not cored and there is no welltest data. Therefore estimation of these parameters is a challenge in reservoirs with no coring sample and welltest data. One of the most powerful tools to estimate permeability from well logs is Artificial Neural Network (ANN) whose advantages and disadvantages have been discussed by several authors [2]. In this...
The estimation of formation permeability in a carbonate reservoir using an artificial neural network
, Article Petroleum Science and Technology ; Vol. 30, issue. 10 , Apr , 2010 , p. 1021-1030 ; ISSN: 10916466 ; Masihi, M ; Fatholah,i S ; Sharif University of Technology
Abstract
Reservoir permeability is an important parameter that its reliable prediction is necessary for reservoir performance assessment and management. Although many empirical formulas are derived regarding permeability and porosity in sandstone reservoirs, these correlations cannot be accurately depicted in carbonate reservoir for the wells that are not cored and for which there are no welltest data. Therefore, having a framework for estimation of these parameters in reservoirs with neither coring samples nor welltest data is crucial. Rock properties are characterized by using different well logs. However, there is no specific petrophysical log for estimating rock permeability; thus, new methods...
Analysis of porosity distribution of large-scale porous media and their reconstruction by Langevin equation
, Article Physical Review E - Statistical, Nonlinear, and Soft Matter Physics ; Volume 83, Issue 2 , February , 2011 ; 15393755 (ISSN) ; Sahimi, M ; Rasaei, M. R ; Tabar, M. R. R ; Sharif University of Technology
Abstract
Several methods have been developed in the past for analyzing the porosity and other types of well logs for large-scale porous media, such as oil reservoirs, as well as their permeability distributions. We developed a method for analyzing the porosity logs φ(h) (where h is the depth) and similar data that are often nonstationary stochastic series. In this method one first generates a new stationary series based on the original data, and then analyzes the resulting series. It is shown that the series based on the successive increments of the log y(h)=φ(h+δh)-φ(h) is a stationary and Markov process, characterized by a Markov length scale hM. The coefficients of the Kramers-Moyal expansion for...
Permeability modeling using ANN and collocated cokriging
, Article 72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 ; Volume 5 , 2010 , Pages 3939-3943 ; 9781617386671 (ISBN) ; Masihi, M ; Sharif University of Technology
Society of Petroleum Engineers
2010
Abstract
Obtaining a reliable reservoir permeability map that is consistent with all available data is of great important for reservoir engineers. However, there is not enough core from existing wells to estimate the reservoir permeability directly but Well log data are more widely available. This study aims to model permeability within the reservoir while there is no enough data. In particular, we use artificial neural networks to estimate permeability using four input logs of sonic, gravity, porosity and neutron logs in six existing wells. In order to eliminate the correlated data, we have done Principal Component Analysis on selected input logs. Collocated cokriging is considered as a valuable...
Casing failure in salt rock: numerical investigation of its causes
, Article Rock Mechanics and Rock Engineering ; Volume 53, Issue 9 , 2020 , Pages 3903-3918 ; Pak, A ; Sharif University of Technology
Springer
2020
Abstract
Numerous cases of casing failure have been reported worldwide. Depletion-induced compaction is one of the main factors that may cause casing failure. Stress perturbation in salt layers may accommodate rock flow which endangers the stability of cased wells. Besides, poor cementing jobs are recognized as one of the wellbore instability causes. These factors need to be considered to determine the mechanism behind the casing failure. In this study, the creep behavior of the caprock salt layer in the southwest Iranian oil fields is experimentally studied through a number of creep tests under conditions of elevated temperature and pressure. Then, a three-dimensional finite element analysis is...
Design and Construction of a Density Prob with Experimental Measurments
, M.Sc. Thesis Sharif University of Technology ; Sohrabpour, Mostafa (Supervisor)
Abstract
In this project a dual density logging tool has been designed and constructed for measuring the bulk density of a formation using gamma rays. One of the main applications of this tool is obtaining porosity. It also is useful in the detection of formations containing oil and gas. In this work, MCNP Monte Carlo code was used to simulate the performance of the scattered gamma rays under various sond-formation parametric condition. The results coming from this code are applied to determine the fundamental parameters of gamma-gamma density tools like, Energy window, thickness of lead, optimum distance between each detectors. Furthermore, a novel method based on summation of back scatter and...
Design and Construction of a Neutron Porosity Probe and Comparison of its Experimental Measurement with MCNP Simulation Results
, M.Sc. Thesis Sharif University of Technology ; SohrabPour, Mostafa (Supervisor)
Abstract
Today the hydrocarbon materials rank in the list of requirements of the modern societies. The increased growth of the human population, their industrial economic activities, transportation etc. requires sufficient supplies of our resources. Therefore, the hydrocarbon resources need to be discovered and evaluated accurately. There are different methods that are used to measure underground hydrocarbon resources such as well logging. In this method, a measuring device is lowered into a well to evaluate several parameter of the surrounding soil. Nuclear well logging is a sub category of well logging that uses nuclear rays to do this measurement. This method has different types of sondes which...
Performance Analysis and Design of Spectral Noise Logging Tool
, M.Sc. Thesis Sharif University of Technology ; Movahedian, Hamid (Supervisor)
Abstract
Today, one of the most important concerns of oil and gas wells is to increase the efficiency of wells. To increase efficiency, well integrity must be monitored. One of the factors that destroy the integrity of the well is the creation of hydraulic fractures inside the oil and gas wells, which is one of the main factors that reduce the efficiency of the well. Hydraulic fractures cause water, gas and other materials to leak into the well or oil and gas to leak out of the fracture, which in both cases reduces the efficiency of the well. One of the most important technologies for identifying hydraulic fractures is the use of SNL tools from oil and gas wells. The oil and gas well SNL tool listens...
An approach to defining tortuosity and cementation factor in carbonate reservoir rocks
, Article Journal of Petroleum Science and Engineering ; Volume 60, Issue 2 , 2008 , Pages 125-131 ; 09204105 (ISSN) ; Javaherian, A ; Pishvaie, M. R ; Nabi Bidhendi, M ; Sharif University of Technology
2008
Abstract
Tortuosity and cementation factor are two critical parameters that significantly affect estimates of reservoir properties. Tortuosity factor can be used to estimate permeability using the Carman-Kozeny equation and is an important parameter for formation resistivity factor calculation using a modified version of Archie's formula. It is also used to predict water saturation of reservoir rocks. Tortuosity as an input parameter in Biot's equation can be used to estimate velocity dispersion. In this work, based on the Generalized Archie Equation Curve Fitting (GAECF), tortuosity and cementation factor are determined for selected intervals in a carbonate reservoir. Formation resistivity factor...
A geomechanical approach to casing collapse prediction in oil and gas wells aided by machine learning
, Article Journal of Petroleum Science and Engineering ; Volume 196 , 2021 ; 09204105 (ISSN) ; Ghorbani, H ; Wood, D. A ; Mehrad, M ; Davoodi, S ; Rashidi, S ; Soleimanian, A ; Shahvand, A. K ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The casing-collapse hazard is one that drilling engineers seek to mitigate with careful well design and operating procedures. However, certain rock formations and their fluid pressure and stress conditions are more prone to casing-collapse risks than others. The Gachsaran Formation in south west Iran, is one such formation, central to oil and gas resource exploration and development in the Zagros region and consisting of complex alternations of anhydrite, marl and salt. The casing-collapse incidents in this formation have resulted over decades in substantial lost production and remedial costs to mitigate the issues surrounding wells with failed casing string. High and vertically-varying...
Integration of adaptive neuro-fuzzy inference system, neural networks and geostatistical methods for fracture density modeling
, Article Oil and Gas Science and Technology ; Vol. 69, issue. 7 , 2014 , pp. 1143-1154 ; ISSN: 12944475 ; Kadkhodaie-Ilkhchi, A ; Sharghi, Y ; Ghaedi, M ; Sharif University of Technology
Abstract
Image logs provide useful information for fracture study in naturally fractured reservoir. Fracture dip, azimuth, aperture and fracture density can be obtained from image logs and have great importance in naturally fractured reservoir characterization. Imaging all fractured parts of hydrocarbon reservoirs and interpreting the results is expensive and time consuming. In this study, an improved method to make a quantitative correlation between fracture densities obtained from image logs and conventional well log data by integration of different artificial intelligence systems was proposed. The proposed method combines the results of Adaptive Neuro-Fuzzy Inference System (ANFIS) and Neural...
Experimental study of the effects of IFT and hysteresis on resistivity and capillary pressure of carbonate rocks
, Article Energy Sources, Part A: Recovery, Utilization and Environmental Effects ; Volume 37, Issue 12 , May , 2015 , Pages 1346-1353 ; 15567036 (ISSN) ; Masihi, M ; Al Ajmi, A ; Al Wahaibi, T ; Al Wahaibi, Y ; Sharif University of Technology
Taylor and Francis Inc
2015
Abstract
Characterizing the electrical resistance of the formation rock is of great importance in, for example, interpreting the well log data, calculating the porosity, and water saturation for the formation rocks. The relation between the resistivity factor and porosity and also between the resistivity index and water saturation (Archie equation) in the formation rock uses the parameters, such as the cementation factor and saturation exponent. However, the direct application of Archie equation to carbonate rocks that are very heterogeneous and mostly oil-wet needs further investigation. In this experimental work, the effects of overburden pressure, temperature, and interfacial tension on the...