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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Korektorské vlastnosti sedimentárních hornin z karotážních měření / Well log analysis for sedimentary formation evaluation

Šálek, Ondřej January 2013 (has links)
3 ABSTRACT The work is focused on analysis of five structural well profiles penetrating sediments of the Bohemian Cretaceous Basin and the underlying Upper Palaeozoic continental basins to the crystalline basement. The objectives of well profile analysis are sedimentary formation evaluation from well log analysis and statistical analysis and evaluation of some physical properties of sedimentary rocks, which have been determined by measurements of drill cores. The aim of the work is to verify the possibility of porosity evaluation from well log analysis in the Bohemian Cretaceous Basin and the underlying Upper Palaeozoic continental basins. The next aim is to compare different geological environments with respect to physical properties of rocks. The content of the work involves presentation of well log curves, computation of porosity values and comparison between the resulting values of porosity from resistivity log, acoustic log and neutron-neutron log and from laboratory measurements of drill core samples. Data from five deep structural wells are used. Different geological environments were compared by statistical methods with respect to physical properties of rocks measured on well core samples from these five wells. Porosity evaluation from well log analysis is difficult but it is possible provided that...
12

Stanovení mechanických parametrů horninového prostředí pomocí analýzy plného vlnového obrazu z akustické karotáže / Determination of mechanical parameters of rocks by analyzing full wave acoustic well logging record

Chalupa, František January 2010 (has links)
In this diploma thesis is at first a revision of field used process of interpretation of full acoustic well logging record in WellCAD program. This program uses an algorithm based on velocity analysis which uses semblance principle. Furthermore an independent interpretation of same data has been done in MATLAB program. In this one, individual steps of the process are verified using analysis of complex seismic trace - in particular by using instantaneous frequency. Both processes of interpretation were applied on wide spectrum of Bohemian Massif rocks with very different mechanic properties, so their robustness has been tested. The results of both interpretation processes have been compared and there haven't been found any fundamental differences, just minor, which can't be systematically eliminated with regard to WellCAD's capabilities. Interpreted values of Poisson's ratio and velocities of longitudinal and transversal have been used for comparison. As the credibility of mechanic parameters' values determined by interpretation processes mentioned above has been proven, other reasons of difference between mechanic parameters' values determined seismically and using static methods were searched for. At first a comparison of basic aspects in which the measuring methods differ (e.g. sample size,...
13

Well-log based determination of rock thermal conductivity in the North German Basin

Fuchs, Sven January 2013 (has links)
In sedimentary basins, rock thermal conductivity can vary both laterally and vertically, thus altering the basin’s thermal structure locally and regionally. Knowledge of the thermal conductivity of geological formations and its spatial variations is essential, not only for quantifying basin evolution and hydrocarbon maturation processes, but also for understanding geothermal conditions in a geological setting. In conjunction with the temperature gradient, thermal conductivity represents the basic input parameter for the determination of the heat-flow density; which, in turn, is applied as a major input parameter in thermal modeling at different scales. Drill-core samples, which are necessary to determine thermal properties by laboratory measurements, are rarely available and often limited to previously explored reservoir formations. Thus, thermal conductivities of Mesozoic rocks in the North German Basin (NGB) are largely unknown. In contrast, geophysical borehole measurements are often available for the entire drilled sequence. Therefore, prediction equations to determine thermal conductivity based on well-log data are desirable. In this study rock thermal conductivity was investigated on different scales by (1) providing thermal-conductivity measurements on Mesozoic rocks, (2) evaluating and improving commonly applied mixing models which were used to estimate matrix and pore-filled rock thermal conductivities, and (3) developing new well-log based equations to predict thermal conductivity in boreholes without core control. Laboratory measurements are performed on sedimentary rock of major geothermal reservoirs in the Northeast German Basin (NEGB) (Aalenian, Rhaethian-Liassic, Stuttgart Fm., and Middle Buntsandstein). Samples are obtained from eight deep geothermal wells that approach depths of up to 2,500 m. Bulk thermal conductivities of Mesozoic sandstones range between 2.1 and 3.9 W/(m∙K), while matrix thermal conductivity ranges between 3.4 and 7.4 W/(m∙K). Local heat flow for the Stralsund location averages 76 mW/m², which is in good agreement to values reported previously for the NEGB. For the first time, in-situ bulk thermal conductivity is indirectly calculated for entire borehole profiles in the NEGB using the determined surface heat flow and measured temperature data. Average bulk thermal conductivity, derived for geological formations within the Mesozoic section, ranges between 1.5 and 3.1 W/(m∙K). The measurement of both dry- and water-saturated thermal conductivities allow further evaluation of different two-component mixing models which are often applied in geothermal calculations (e.g., arithmetic mean, geometric mean, harmonic mean, Hashin-Shtrikman mean, and effective-medium theory mean). It is found that the geometric-mean model shows the best correlation between calculated and measured bulk thermal conductivity. However, by applying new model-dependent correction, equations the quality of fit could be significantly improved and the error diffusion of each model reduced. The ‘corrected’ geometric mean provides the most satisfying results and constitutes a universally applicable model for sedimentary rocks. Furthermore, lithotype-specific and model-independent conversion equations are developed permitting a calculation of water-saturated thermal conductivity from dry-measured thermal conductivity and porosity within an error range of 5 to 10%. The limited availability of core samples and the expensive core-based laboratory measurements make it worthwhile to use petrophysical well logs to determine thermal conductivity for sedimentary rocks. The approach followed in this study is based on the detailed analyses of the relationships between thermal conductivity of rock-forming minerals, which are most abundant in sedimentary rocks, and the properties measured by standard logging tools. By using multivariate statistics separately for clastic, carbonate and evaporite rocks, the findings from these analyses allow the development of prediction equations from large artificial data sets that predict matrix thermal conductivity within an error of 4 to 11%. These equations are validated successfully on a comprehensive subsurface data set from the NGB. In comparison to the application of earlier published approaches formation-dependent developed for certain areas, the new developed equations show a significant error reduction of up to 50%. These results are used to infer rock thermal conductivity for entire borehole profiles. By inversion of corrected in-situ thermal-conductivity profiles, temperature profiles are calculated and compared to measured high-precision temperature logs. The resulting uncertainty in temperature prediction averages < 5%, which reveals the excellent temperature prediction capabilities using the presented approach. In conclusion, data and methods are provided to achieve a much more detailed parameterization of thermal models. / Die thermische Modellierung des geologischen Untergrundes ist ein wichtiges Werkzeug bei der Erkundung und Bewertung tiefliegender Ressourcen sedimentärer Becken (e.g., Kohlenwasserstoffe, Wärme). Die laterale und vertikale Temperaturverteilung im Untergrund wird, neben der Wärmestromdichte und der radiogenen Wärmeproduktion, hauptsächlich durch die Wärmeleitfähigkeit (WLF) der abgelagerten Gesteinsschichten bestimmt. Diese Parameter stellen die wesentlichen Eingangsgrößen für thermische Modelle dar. Die vorliegende Dissertation befasst sich mit der Bestimmung der Gesteins-WLF auf verschiedenen Skalen. Dies umfasst (1) laborative WLF-Messungen an mesozoischen Bohrkernproben, (2) die Evaluierung und Verbesserung der Prognosefähigkeit von Mischgesetzten zur Berechnung von Matrix- und Gesamt-WLF sedimentärer Gesteine, sowie (3) die Entwicklung neuer Prognosegleichungen unter Nutzung bohrlochgeophysikalischer Messungen und multivariater Analysemethoden im NGB. Im Nordostdeutschen Becken (NEGB) wurden für die wichtigsten geothermischen Reservoire des Mesozoikums (Aalen, Rhät-Lias-Komplex, Stuttgart Formation, Mittlerer Buntsandstein) Bohrkerne geothermischer Tiefbohrungen (bis 2.500 m Tiefe) auf Ihre thermischen und petrophysikalischen Eigenschaften hin untersucht. Die WLF mesozoischer Sandsteine schwankt im Mittel zwischen 2,1 und 3,9 W/(m∙K), die WLF der Gesteinsmatrix hingegen im Mittel zwischen 3,4 und 7,4 W/(m∙K). Neu berechnete Werte zur Oberflächenwärmestromdichte (e.g., 76 mW/m², Stralsund) stehen im Einklang mit den Ergebnissen früherer Studien im NEGB. Erstmals im NDB wurde für das mesozoisch/känozoischen Intervall am Standort Stralsund ein in-situ WLF-Profil berechnet. In-situ Formations-WLF, für als potentielle Modelschichten interessante, stratigraphische Intervalle, variieren im Mittel zwischen 1,5 und 3,1 W/(m∙K) und bilden eine gute Grundlage für kleinskalige (lokale) thermische Modelle. Auf Grund der in aller Regel nur eingeschränkt verfügbaren Bohrkernproben sowie des hohen laborativen Aufwandes zur Bestimmung der WLF waren alternative Methoden gesucht. Die Auswertung petrophysikalischer Bohrlochmessungen mittels mathematischer-statistischer Methoden stellt einen lang genutzten und erprobten Ansatz dar, welcher in seiner Anwendbarkeit jedoch auf die aufgeschlossenen Gesteinsbereiche (Genese, Geologie, Stratigraphie, etc.) beschränkt ist. Daher wurde ein leicht modifizierter Ansatz entwickelt. Die thermophysikalischen Eigenschaften der 15 wichtigsten gesteinsbildenden Minerale (in Sedimentgesteinen) wurden statistisch analysiert und aus variablen Mischungen dieser Basisminerale ein umfangreicher, synthetischer Datensatz generiert. Dieser wurde mittels multivariater Statistik bearbeitet, in dessen Ergebnis Regressionsgleichungen zur Prognose der Matrix-WLF für drei Gesteinsgruppen (klastisch, karbonatisch, evaporitisch) abgeleitet wurden. In einem zweiten Schritt wurden für ein Echtdatenset (laborativ gemessene WLF und Standardbohrlochmessungen) empirische Prognosegleichungen für die Berechnung der Gesamt-WLF entwickelt. Die berechneten WLF zeigen im Vergleich zu gemessenen WLF Fehler zwischen 5% und 11%. Die Anwendung neu entwickelter, sowie in der Literatur publizierter Verfahren auf den NGB-Datensatz zeigt, dass mit den neu aufgestellten Gleichungen stets der geringste Prognosefehler erreicht wird. Die Inversion neu berechneter WLF-Profile erlaubt die Ableitung synthetischer Temperaturprofile, deren Vergleich zu gemessenen Gesteinstemperaturen in einen mittleren Fehler von < 5% resultiert. Im Rahmen geothermischer Berechnungen werden zur Umrechnung zwischen Matrix- und Gesamt-WLF häufig Zwei-Komponenten-Mischmodelle genutzt (Arithmetisches Mittel, Harmonische Mittel, Geometrisches Mittel, Hashin-Shtrikman Mittel, Effektives-Medium Mittel). Ein umfangreicher Datensatz aus trocken- und gesättigt-gemessenen WLF und Porosität erlaubt die Evaluierung dieser Modelle hinsichtlich Ihrer Prognosefähigkeit. Diese variiert für die untersuchten Modelle stark (Fehler: 5 – 53%), wobei das geometrische Mittel die größte, quantitativ aber weiterhin unbefriedigende Übereinstimmungen zeigt. Die Entwicklung und Anwendung mischmodelspezifischer Korrekturgleichungen führt zu deutlich reduzierten Fehlern. Das korrigierte geometrische Mittel zeigt dabei, bei deutlich reduzierter Fehlerstreubreite, erneut die größte Übereinstimmung zwischen berechneten und gemessenen Werten und scheint ein universell anwendbares Mischmodel für sedimentäre Gesteine zu sein. Die Entwicklung modelunabhängiger, gesteinstypbezogener Konvertierungsgleichungen ermöglicht die Abschätzung der wassergesättigten Gesamt-WLF aus trocken-gemessener WLF und Porosität mit einem mittleren Fehler < 9%. Die präsentierten Daten und die neu entwickelten Methoden erlauben künftig eine detailliertere und präzisere Parametrisierung thermischer Modelle sedimentärer Becken.
14

Aproximace statických modulů hornin z dynamických modulů stanovených akustickou karotáží pomocí T-matrix modelu / Approximation of static moduli of rocks from dynamic moduli determined by sonic well logging using T-matrix model

Chalupa, František January 2019 (has links)
(EN) Thesis deals with an approximation of static moduli in wells from dynamic moduli determined by acoustic well logging using T-matrix model. Proposed approach makes possible to determine moduli values, which are close to values of static moduli, which would be determined by loading tests. This approach is based on an idea, that an intact rock with sufficiently high compressional strength sc and sufficiently high value of static Young's modulus Es, manifests more or less linear elastic behaviour. In such case, the values of static and dynamic moduli are identical. This fact has been experimentally verified for rocks with values of sc and Es in order of higher tens of MPa and GPa respectively. In case of a rock damage presence in such rock, it's behaviour becomes nonlinearly elastic. The amount of nonlinearity is proportional to increasing amount of rock damage. This results in the difference between values of static and dynamic moduli. T-matrix model is used to quantify this difference. This model is based on an anisotropic rock matrix with ellipsoidal inclusions. These inclusions can affect each other. The result of this model calculation is a group of values of elastic constants, which we call effective moduli. These effective moduli include the effect of porosity in the rock as well and they...
15

Subsurface Framework and Fault Timing in the Missourian Granite Wash Interval, Stiles Ranch and Mills Ranch Fields, Wheeler County, Texas

Lomago, Brendan Michael 14 December 2018 (has links)
The recent and rapid growth of horizontal drilling in the Anadarko basin necessitates newer studies to characterize reservoir and source rock quality in the region. Most oil production in the basin comes from the Granite Wash reservoirs, which are composed of stacked tight sandstones and conglomerates that range from Virgillian (305-299 Ma) to Atokan (311-309.4 Ma) in age. By utilizing geophysical well logging data available in raster format, the Granite Wash reservoirs and their respective marine flooding surfaces were stratigraphically mapped across the regional fault systems. Additionally, well log trends were calibrated with coincident core data to minimize uncertainty regarding facies variability and lateral continuity of these intervals. In this thesis, inferred lithofacies were grouped into medium submarine fan lobe, distal fan lobe, and offshore facies (the interpreted depositional environments). By creating isopach and net sand maps in Petra, faulting in the Missourian was determined to have occurred syndepositionally at the fifth order scale of stratigraphic hierarchy.
16

Seismic and Well Log Attribute Analysis of the Jurassic Entrada/Curtis Interval Within the North Hill Creek 3D Seismic Survey, Uinta Basin, Utah, A Case History

ONeal, Ryan J. 18 July 2007 (has links) (PDF)
3D seismic attribute analysis of the Jurassic Entrada/Curtis interval within the North Hill Creek (NHC) survey has been useful in delineating reservoir quality eolian-influenced dune complexes. Amplitude, average reflection strength and spectral decomposition appear to be most useful in locating reservoir quality dune complexes, outlining their geometry and possibly displaying lateral changes in thickness. Cross sectional views displaying toplap features likely indicate an unconformity between Entrada clinoforms below and Curtis planar beds above. This relationship may aid the explorationist in discovering this important seismic interval. Seismic and well log attribute values were cross plotted and have revealed associations between these data. Cross plots are accompanied by regression lines and R2 values which support our interpretations. Although reservoir quality dune complexes may be delineated, the Entrada/Curtis play appears to be mainly structural. The best producing wells in the survey are associated with structural or stratigraphic relief and the thickest Entrada/Curtis intervals. Structural and stratigraphic traps are not always associated with laterally extensive dune complexes. Time structure maps as well as isochron maps have proven useful in delineating the thickest and/or gas prone portions of the Entrada/Curtis interval as well as areas with structural and stratigraphic relief. We have observed that the zones of best production are associated with low gamma ray (40-60 API) values. These low values are associated with zones of high amplitude. Thus, max peak amplitude as a seismic attribute may delineate areas of higher sand content (i.e. dune complexes) whereas zones of low amplitude may represent areas of lower sand content (i.e. muddier interdune or tidal flat facies). Lack of significant average porosity does not seem to be related to a lack of production. In fact, the best producing wells have been drilled in Entrada/Curtis intervals where average porosity is near 4 %. There are however zones within the upper portion of the Entrada/Curtis that are 40 ft. (12.2 m) thick and have porosities between 14% and 20%. By combining derived attribute maps with observed cross plot relationships, it appears that the best producing intervals within the Entrada/Curtis are those associated with high amplitudes, API values from 40-60 and structural relief.
17

Characterization of a Utica Shale Reflector Package Using Well Log Data and Amplitude Variation with Offset Analysis

Butterfield, Andrei 06 June 2014 (has links)
No description available.
18

Contribuição ao conhecimento do meio físico da região do lixão de São Carlos - SP, através de estudos geológicos, geofísicos, topográficos e químicos / Contribution to environment\'s knowledge of the Sao Carlos - SP waste dump area - by geological, geophysical, topographical and chemical studies

Álvares, Cyro Martins Bicudo 13 June 2000 (has links)
O lixão da cidade de São Carlos foi colocado, aproximadamente por dezessete anos, em uma boçoroca formada em região sedimentar, sobre os arenitos da Formação Botucatu, sem nenhuma espécie de controle prévio, quanto a possibilidade de contaminação do meio físico e, especialmente da água subterrânea. Dada essa possibilidade de contaminação do aqüífero profundo, uma série de estudos são feitos no local, desde a década de 80. Este trabalho vem somar-se aos diversos outros na tentativa de aprofundar o conhecimento das condições em que se encontra o meio físico na região do lixão. Fazendo parte de um projeto maior este trabalho procurou, utilizando as ciências de geologia, geofísica, topografia e química, dar novos elementos e interpretações a esse conhecimento. Geologicamente, detectamos e avaliamos a presença de camadas penetrativas, hidraulicamente menos condutivas, como areias siltosas e, muito provavelmente, arenito silicificado ou diabásio em profundidade, o que poderia fazer que a contaminação não atingisse o aqüífero profundo. Para isso utilizamos o mapeamento geológico e a geofísica em três de suas técnicas: caminhamento elétrico, sondagens elétricas verticais e perfilagem de poços. Quimicamente, avaliamos a contaminação das águas subterrâneas em relação ao sentido do fluxo. / For seventeen years, Sao Carlos\' solid wastes were placed in a gully formed in a sedimentary area, on the Botucatu Formation (friable sandstone and sands), without any form of control to prevent the contamination of the environment and, especially, of the ground water. Thanks to the possibility of contamination of the deep water source, a series of studies have been made in the area since the eighties. These studies were just another attempt, along with severaI others, to increase the knowledge of the environmental conditions surrounding the waste dump area. Being part of a greater project, different sciences were used such as geology, geophysics, topography and chemistry, in order to obtain new elements and a more acurate interpretation to the existing knowledge. Geologicaly, we detected a less hydraulicaly conductive silty sand layers and, probably, silicificated sandstone layers or diabase sill which could protect the deep water sources from being contaminated. Geologic mapping and geophysical techniques such as electric surveys and well logs were performed during the process. Chemically, we evaluated the ground water contamination in relation to the flow\'s direction.
19

Contribuição ao conhecimento do meio físico da região do lixão de São Carlos - SP, através de estudos geológicos, geofísicos, topográficos e químicos / Contribution to environment\'s knowledge of the Sao Carlos - SP waste dump area - by geological, geophysical, topographical and chemical studies

Cyro Martins Bicudo Álvares 13 June 2000 (has links)
O lixão da cidade de São Carlos foi colocado, aproximadamente por dezessete anos, em uma boçoroca formada em região sedimentar, sobre os arenitos da Formação Botucatu, sem nenhuma espécie de controle prévio, quanto a possibilidade de contaminação do meio físico e, especialmente da água subterrânea. Dada essa possibilidade de contaminação do aqüífero profundo, uma série de estudos são feitos no local, desde a década de 80. Este trabalho vem somar-se aos diversos outros na tentativa de aprofundar o conhecimento das condições em que se encontra o meio físico na região do lixão. Fazendo parte de um projeto maior este trabalho procurou, utilizando as ciências de geologia, geofísica, topografia e química, dar novos elementos e interpretações a esse conhecimento. Geologicamente, detectamos e avaliamos a presença de camadas penetrativas, hidraulicamente menos condutivas, como areias siltosas e, muito provavelmente, arenito silicificado ou diabásio em profundidade, o que poderia fazer que a contaminação não atingisse o aqüífero profundo. Para isso utilizamos o mapeamento geológico e a geofísica em três de suas técnicas: caminhamento elétrico, sondagens elétricas verticais e perfilagem de poços. Quimicamente, avaliamos a contaminação das águas subterrâneas em relação ao sentido do fluxo. / For seventeen years, Sao Carlos\' solid wastes were placed in a gully formed in a sedimentary area, on the Botucatu Formation (friable sandstone and sands), without any form of control to prevent the contamination of the environment and, especially, of the ground water. Thanks to the possibility of contamination of the deep water source, a series of studies have been made in the area since the eighties. These studies were just another attempt, along with severaI others, to increase the knowledge of the environmental conditions surrounding the waste dump area. Being part of a greater project, different sciences were used such as geology, geophysics, topography and chemistry, in order to obtain new elements and a more acurate interpretation to the existing knowledge. Geologicaly, we detected a less hydraulicaly conductive silty sand layers and, probably, silicificated sandstone layers or diabase sill which could protect the deep water sources from being contaminated. Geologic mapping and geophysical techniques such as electric surveys and well logs were performed during the process. Chemically, we evaluated the ground water contamination in relation to the flow\'s direction.
20

Application of hybrid uncertainty-clustering approach in pre-processing well-logs / Application de l'approche hybride incertitude-partitionnement pour le prétraitement des données de diagraphie

Masoudi, Pedram 16 May 2017 (has links)
La thèse est principalement centrée sur l'étude de la résolution verticale des diagraphies. On outre, l'arithmétique floue est appliquée aux modèles expérimentaux pétrophysiques en vue de transmettre l'incertitude des données d'entrée aux données de sortie, ici la saturation irréductible en eau et la perméabilité. Les diagraphies sont des signaux digitaux dont les données sont des mesures volumétriques. Le mécanisme d'enregistrement de ces données est modélisé par des fonctions d'appartenance floues. On a montré que la Résolution Verticale de la Fonction d'Appartenance (VRmf) est supérieur d'espacement. Dans l'étape suivante, la fréquence de Nyquist est revue en fonction du mécanisme volumétrique de diagraphie ; de ce fait, la fréquence volumétrique de Nyquist est proposée afin d'analyser la précision des diagraphies. Basé sur le modèle de résolution verticale développée, un simulateur géométrique est conçu pour générer les registres synthétiques d'une seule couche mince. Le simulateur nous permet d'analyser la sensibilité des diagraphies en présence d'une couche mince. Les relations de régression entre les registres idéaux (données d'entrée de ce simulateur) et les registres synthétiques (données de sortie de ce simulateur) sont utilisées comme relations de déconvolution en vue d'enlever l'effet des épaules de couche d'une couche mince sur les diagraphies GR, RHOB et NPHI. Les relations de déconvolution ont bien été appliquées aux diagraphies pour caractériser les couches minces. Par exemple, pour caractériser une couche mince poreuse, on a eu recours aux données de carottage qui étaient disponibles pour la vérification : NPHI mesuré (3.8%) a été remplacé (corrigé) par 11.7%. NPHI corrigé semble être plus précis que NPHI mesuré, car la diagraphie a une valeur plus grande que la porosité de carottage (8.4%). Il convient de rappeler que la porosité totale (NPHI) ne doit pas être inférieure à la porosité effective (carottage). En plus, l'épaisseur de la couche mince a été estimée à 13±7.5 cm, compatible avec l'épaisseur de la couche mince dans la boite de carottage (<25 cm). Normalement, l'épaisseur in situ est inférieure à l'épaisseur de la boite de carottage, parce que les carottes obtenues ne sont plus soumises à la pression lithostatique, et s'érodent à la surface du sol. La DST est appliquée aux diagraphies, et l'intervalle d'incertitude de DST est construit. Tandis que la VRmf des diagraphies GR, RHOB, NPHI et DT est ~60 cm, la VRmf de l'intervalle d'incertitude est ~15 cm. Or, on a perdu l'incertitude de la valeur de diagraphie, alors que la VRmf est devenue plus précise. Les diagraphies ont été ensuite corrigées entre l'intervalle d'incertitude de DST avec quatre simulateurs. Les hautes fréquences sont amplifiées dans les diagraphies corrigées, et l'effet des épaules de couche est réduit. La méthode proposée est vérifiée dans les cas synthétiques, la boite de carottage et la porosité de carotte. L'analyse de partitionnement est appliquée aux diagraphies NPHI, RHOB et DT en vue de trouver l'intervalle d'incertitude, basé sur les grappes. Puis, le NPHI est calibré par la porosité de carottes dans chaque grappe. Le √MSE de NPHI calibré est plus bas par rapport aux cinq modèles conventionnels d'estimation de la porosité (au minimum 33% d'amélioration du √MSE). Le √MSE de généralisation de la méthode proposée entre les puits voisins est augmenté de 42%. L'intervalle d'incertitude de la porosité est exprimé par les nombres flous. L'arithmétique floue est ensuite appliquée dans le but de calculer les nombres flous de la saturation irréductible en eau et de la perméabilité. Le nombre flou de la saturation irréductible en eau apporte de meilleurs résultats en termes de moindre sous-estimation par rapport à l'estimation nette. Il est constaté que lorsque les intervalles de grappes de porosité ne sont pas compatibles avec la porosité de carotte, les nombres flous de la perméabilité ne sont pas valables. / In the subsurface geology, characterization of geological beds by well-logs is an uncertain task. The thesis mainly concerns studying vertical resolution of well-logs (question 1). In the second stage, fuzzy arithmetic is applied to experimental petrophysical relations to project the uncertainty range of the inputs to the outputs, here irreducible water saturation and permeability (question 2). Regarding the first question, the logging mechanism is modelled by fuzzy membership functions. Vertical resolution of membership function (VRmf) is larger than spacing and sampling rate. Due to volumetric mechanism of logging, volumetric Nyquist frequency is proposed. Developing a geometric simulator for generating synthetic-logs of a single thin-bed enabled us analysing sensitivity of the well-logs to the presence of a thin-bed. Regression-based relations between ideal-logs (simulator inputs) and synthetic-logs (simulator outputs) are used as deconvolution relations for removing shoulder-bed effect of thin-beds from GR, RHOB and NPHI well-logs. NPHI deconvolution relation is applied to a real case where the core porosity of a thin-bed is 8.4%. The NPHI well-log is 3.8%, and the deconvolved NPHI is 11.7%. Since it is not reasonable that the core porosity (effective porosity) be higher than the NPHI (total porosity), the deconvolved NPHI is more accurate than the NPHI well-log. It reveals that the shoulder-bed effect is reduced in this case. The thickness of the same thin-bed was also estimated to be 13±7.5 cm, which is compatible with the thickness of the thin-bed in the core box (<25 cm). Usually, in situ thickness is less than the thickness of the core boxes, since at the earth surface, there is no overburden pressure, also the cores are weathered. Dempster-Shafer Theory (DST) was used to create well-log uncertainty range. While the VRmf of the well-logs is more than 60 cm, the VRmf of the belief and plausibility functions (boundaries of the uncertainty range) would be about 15 cm. So, the VRmf is improved, while the certainty of the well-log value is lost. In comparison with geometric method, DST-based algorithm resulted in a smaller uncertainty range of GR, RHOB and NPHI logs by 100%, 71% and 66%, respectively. In the next step, cluster analysis is applied to NPHI, RHOB and DT for the purpose of providing cluster-based uncertainty range. Then, NPHI is calibrated by core porosity value in each cluster, showing low √MSE compared to the five conventional porosity estimation models (at least 33% of improvement in √MSE). Then, fuzzy arithmetic is applied to calculate fuzzy numbers of irreducible water saturation and permeability. Fuzzy number of irreducible water saturation provides better (less overestimation) results than the crisp estimation. It is found that when the cluster interval of porosity is not compatible with the core porosity, the permeability fuzzy numbers are not valid, e.g. in well#4. Finally, in the possibilistic approach (the fuzzy theory), by calibrating α-cut, the right uncertainty interval could be achieved, concerning the scale of the study.

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