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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.
21

Tectonic Evolution of Taimyr in the Late Paleozoic to Mesozoic from Provenance and Thermochronological Evidence

Zhang, Xiaojing January 2015 (has links)
The Taimyr Peninsula is a key element in the circum-Arctic region and represents thenorthern margin of the Siberian Craton. The Taimyr Peninsula is a late Paleozoic fold andthrust belt and preserves late Paleozoic through Mesozoic siliciclastic sedimentarysuccessions and providing an ideal location to investigate the Paleozoic to Mesozoictectonic evolution associated with the Uralian orogeny, the Siberian Trap magmatism andopening of Amerasia Basin within a circum-Arctic framework. Multiple methods areadopted, including petrography, heavy mineral analysis and detrital zircon U-Pbgeochronology for provenance investigation, apatite fission track dating for revealingthermal history and balanced cross section for understanding the deformation style ofTaimyr.The results of this thesis indicate that the Late Carboniferous to Permian sediments ofsouthern Taimyr were deposited in a pro-foreland basin of the Uralian orogen during theUralian orogeny. In the Triassic, the siliciclastic deposits still show a strong Uraliansignature but the initiation of Siberian Trap-related input begins to be significant. Erosionof the Uralian orogen has reached a deep metamorphic level. By Late Jurassic andCretaceous time, the deposition setting of southern Taimyr is an intracratonic basin.Erosion and input from Uralian sources waned while greater input from SiberianTrap-related rocks of the Taimyr region dominated. The Taimyr Peninsula underwent atleast three cooling and uplifting episodes: 280 Ma, 250 Ma and 220 Ma, corresponding tothe Uralian orogeny, the Siberian Traps and the late Triassic transpression. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: In press. Paper 3: Manuscript. Paper 4: Manuscript.</p>
22

Experimental investigation of two-phase flow properties of small core samples

Olafuyi, Olalekan Adisa, Petroleum Engineering, Faculty of Engineering, UNSW January 2008 (has links)
This thesis presents an experimental investigation of two-phase flow properties of porous rock samples having different scales ranging from micro-CT imaging to conventional core plug scales. Advances in micro-CT imaging of porous materials provide the opportunity to extract representative networks from the images. This improves the predictive capability of porescale network models to predict multiphase flow properties. However, all these predictions need to be validated with laboratory data. Micro-CT imaging is currently limited to small sample sizes, having bulk volumes of the order of 0.1 cm??. Conventional core plugs, however, have sizes several orders of magnitude larger than that (bulk volumes of 10 cm?? or larger). The aim of this thesis is to investigate the scale effect on laboratory data and to provide reliable experimental data which can be used to test the predictive value of microCT based network models. Berea and Bentheim sandstones and Mount Gambier carbonate were used in the experiments. The core samples were thoroughly cleaned in order to obtain strongly, uniform water-wet conditions. Simple well-characterized fluid systems were chosen in the experiments: Air-brine fluid-system for drainage capillary pressure, resistivity index and spontaneous imbibition experiments while oil-brine fluid-system for wettability and relative permeability measurements. Drainage capillary pressure, resistivity index, relative permeability and spontaneous imbibition measurements were made on the cores having bulk volumes ranging from 0.1 to 12 cm??. Previous studies have shown that experiments at this scale are still lacking. The wettability was tried to keep strongly water-wet for all experiments. The experimental results show that the measurements of drainage capillary pressure, and resistivity index and spontaneous imbibition on small core samples, having similar scales as micro-CT imaging can be made accurately in the laboratory. The measurement of relative permeability remains challenging. This thesis concludes that commonly used homogeneous rock types (Berea and Bentheim sandstones and Mt. Gambier carbonate) can be considered to be sufficiently homogeneous from the pore to core scale based on the two-phase flow properties examined in this study. Hence, laboratory data taken from these rocks using conventional core plugs can be used to calibrate micro-CT based network models for multiphase flow properties.
23

Φυσική και μηχανική συμπεριφορά πετρωμάτων / Physical and mechanical behavior of rocks

Δασκαλόπουλος, Κωνσταντίνος 14 February 2012 (has links)
Η παρούσα διπλωματική εργασία εξετάζει τα φυσικά και μηχανικά χαρακτηριστικά του βραχώδους υλικού δύο διαφορετικών πετρωμάτων και συγκεκριμένα ψαμμιτών και γρανιτών. Οι ψαμμίτες προέρχονται από πέντε (5) επιλεγμένες θέσεις δειγματοληψίας σε αντίστοιχες θέσεις της Δ. Ελλάδας, από την ακολουθία του φλύσχη που ανήκει και στις τρεις αντιπροσωπευτικές γεωτεκτονικές ζώνες της ευρύτερης περιοχής. Η δειγματοληψία έγινε σε βραχώδη δείγματα μεγάλων διαστάσεων (block samples) και στη συνέχεια διαμορφώθηκαν κυλινδρικά δείγματα με εργαστηριακή καροταρία. Οι γρανίτες προέρχονται από δείγματα σημαντικού αριθμού δειγματοληπτικών γεωτρήσεων που εκτελέστηκαν στα πλαίσια της γεωτεχνικής έρευνας θεμελίωσης αιολικού πάρκου (ανεμογεννητριών) στην περιοχή Πισοδερίου Φλώρινας. Η εργαστηριακή έρευνα περιλάμβανε την προσέγγιση κυρίως της φυσικής συμπεριφοράς των ψαμμιτών με «μη καταστρεπτικές δοκιμές» σε 16 κυλινδρικά διαμορφωμένα δείγματα, ενώ για τους γρανίτες και συγκεκριμένα σε 120 κυλινδρικά δείγματα, έμφαση δόθηκε στις μηχανικές ιδιότητες η οποίες και απαιτούνται για τον ορθολογικό σχεδιασμό του συγκεκριμένου τεχνικού έργου. Οι ψαμμίτες ήταν κυρίως χαλαζιακοί, ασβεστιτικοί – χαλαζιακοί και αρκόζες. Τις χαμηλότερες τιμές ταχύτητας υπερήχων και σκληρότητας παρουσιάζουν οι αρκόζες, ενώ αντίθετα οι χαλαζιακοί ψαμμίτες εμφανίζονται σαν μέτρια σκληροί και με αρκετά χαμηλά πορώδη. Οι γρανίτες εμφανίζονται συνήθως σκληροί, υψηλής – πολύ υψηλής αντοχής με τιμές λόγου μέτρου (MR) να κυμαίνονται από περίπου 600 μέχρι <50. Ο σημαντικός αριθμός εργαστηριακών μετρήσεων κυρίως των παραμέτρων αντοχής επέτρεψε την στατιστική επεξεργασία τους και τη διατύπωση εμπειρικών σχέσεων γενικής εφαρμογής που χαρακτηρίζουν το συγκεκριμένο πέτρωμα. / This thesis examines the physical and mechanical characteristics of the rocky material of two different rocks and specifically sandstones and granites. The sandstones come from five (5) selected sampling sites in corresponding locations of Western Greece, from the sequence of flysch that belongs to all three representative geotectonic zones of the surrounding area. The sampling was done in large rock samples (block samples) and then formed cylindrical samples with laboratory karotaria. The granite samples come from a large number of sample drillings that carried out under the geotechnical research foundation of a wind farm (wind turbines) in Pissoderi Florina. The laboratory investigation included the main approach of the physical behavior of sandstones with "non-destructive testing" in 16 cylindrical shaped samples, while for the granite and specifically for 120 cylindrical samples, emphasis was placed on the mechanical characteristics which are necessary for the rational design of this specific technical project. The sandstones were mainly quartz, limestone - quartz and arkozes. The lowest ultrasound speed value and hardness show the arkozes, while the quartz sandstones appear as medium hard and relatively low porous. The granites usually appear tough, high - very high resistance to ratio value measure (MR) ranging from about 600 to <50. The large number of laboratory measurements of the parameters, mainly resistance’s, allowed the statistical processing and the formulation of empirical relationships of general application that characterize this rock.
24

Diagênese de arenitos e conglomerados aptianos da Bacia de Campos

Carvalho, Awilsa de Souza Gonçalves January 2014 (has links)
Processos diagenéticos controlam a porosidade e permeabilidade dos reservatórios de petróleo. Um estudo petrográfico sistemático de 71 arenitos e conglomerados da Formação Itabapoana (Aptiano), selecionadas de testemunhos de 13 poços na porção offshore da Bacia de Campos, Leste do Brasil, permitiu o reconhecimento dos principais constituintes primários, diagenéticos, tipos de poros e das relações temporais e espaciais entre eles. Essas rochas são contemporâneas aos extensos reservatórios lacustres do “Pré-Sal” atualmente em exploração. As rochas variam de arenitos muito finos a conglomerados, com predominância de arenitos muito grossos, e sua composição detrítica original corresponde a arcósios líticos e litarenitos feldspáticos, ricos em fragmentos de rochas vulcânicas (FRV). Argilominerais esmectíticos são os mais abundantes constituintes diagenéticos, relacionados principalmente à alteração de FRV, minerais pesados e biotita. A história térmica e de soterramento, e o fluxo de fluídos também exerceram um papel fundamental nos processos diagenéticos e na evolução da qualidade de reservatório. Os principais processos diagenéticos registrados foram a dissolução de FRV, feldspatos e minerais pesados, a autigênese de esmectitas, hematita, dolomita, calcita, zeolitas e óxidos de titânio cimentando e substituindo FRV, feldspatos, biotita e minerais pesados, a compactação mecânica e química, e a albitização dos feldspatos, principalmente dos plagioclásios. A porosidade primária intergranular foi fortemente reduzida pela compactação e cimentação por argilominerais esmectíticos, calcita, dolomita e zeolitas. Por outro lado, porosidade secundária foi gerada pela dissolução de constituintes primários e diagenéticos, e por faturamento. Futuros estudos específicos e detalhados, incluindo análises de microscopia eletrônica, difratometria de raios-X e isótopos estáveis, deverão contribuir para um melhor entendimento da distribuição espacial e temporal dos processos diagenéticos nessas rochas, de modo a embasar o desenvolvimento de modelos preditivos quanto à sua qualidade, que possam contribuir para reduzir os riscos envolvidos na sua exploração. / Diagenetic processes control the porosity and permeability of petroleum reservoirs. A systematic study of 71 sandstones and conglomerates of the Itabapoana Formation (Aptian), selected from the cores of 13 wells in the offshore portion of Campos Basin, eastern Brazil, allowed the recognition of the main primary and diagenetic constituents, pore types, and of the space and time relations among them. These rocks are contemporaneous to the extensive lacustrine Pre-Salt carbonate reservoirs under exploration. The rocks range from very fine-grained sandstones to conglomerates, with predominance of very coarse-grained sandstones, and their original detrital composition corresponds to lithic arkoses and feldspathic litharenites, rich in volcanic rock fragments (VFR). Smectitic clay minerals are the most abundant diagenetic constituents, related mostly to the alteration of VRF, heavy minerals and biotite. The burial and thermal history and the flow of fluids also exerted a fundamental role on the diagenetic processes and on the of reservoir quality. The main diagenetic processes recorded were the dissolution of volcanic fragments, feldspars and heavy minerals, the authigenesis of smectites, hematite, dolomite, calcite, zeolites and titanium oxides in intergranular pores and replacing VRF, feldspars, biotite and heavy minerals, mechanical and chemical compaction, and the albitization of feldspars, mostly plagioclase. Primary intergranular porosity was strongly reduced by compaction and smectite, calcite, dolomite and zeolite cementation. On the other hand, secondary porosity was generated by the dissolution of primary and diagenetic constituents, and by fracturing. Future specific and detailed studies, including electron microscopy, X-ray diffraction and stable isotope analyses, shall contribute to a better understanding of the space and time distribution of diagenetic processes in these rocks, in order to support the development of predictive models of their quality that may contribute to the reduction of risks involved in their exploration.
25

Diagênese de arenitos e conglomerados aptianos da Bacia de Campos

Carvalho, Awilsa de Souza Gonçalves January 2014 (has links)
Processos diagenéticos controlam a porosidade e permeabilidade dos reservatórios de petróleo. Um estudo petrográfico sistemático de 71 arenitos e conglomerados da Formação Itabapoana (Aptiano), selecionadas de testemunhos de 13 poços na porção offshore da Bacia de Campos, Leste do Brasil, permitiu o reconhecimento dos principais constituintes primários, diagenéticos, tipos de poros e das relações temporais e espaciais entre eles. Essas rochas são contemporâneas aos extensos reservatórios lacustres do “Pré-Sal” atualmente em exploração. As rochas variam de arenitos muito finos a conglomerados, com predominância de arenitos muito grossos, e sua composição detrítica original corresponde a arcósios líticos e litarenitos feldspáticos, ricos em fragmentos de rochas vulcânicas (FRV). Argilominerais esmectíticos são os mais abundantes constituintes diagenéticos, relacionados principalmente à alteração de FRV, minerais pesados e biotita. A história térmica e de soterramento, e o fluxo de fluídos também exerceram um papel fundamental nos processos diagenéticos e na evolução da qualidade de reservatório. Os principais processos diagenéticos registrados foram a dissolução de FRV, feldspatos e minerais pesados, a autigênese de esmectitas, hematita, dolomita, calcita, zeolitas e óxidos de titânio cimentando e substituindo FRV, feldspatos, biotita e minerais pesados, a compactação mecânica e química, e a albitização dos feldspatos, principalmente dos plagioclásios. A porosidade primária intergranular foi fortemente reduzida pela compactação e cimentação por argilominerais esmectíticos, calcita, dolomita e zeolitas. Por outro lado, porosidade secundária foi gerada pela dissolução de constituintes primários e diagenéticos, e por faturamento. Futuros estudos específicos e detalhados, incluindo análises de microscopia eletrônica, difratometria de raios-X e isótopos estáveis, deverão contribuir para um melhor entendimento da distribuição espacial e temporal dos processos diagenéticos nessas rochas, de modo a embasar o desenvolvimento de modelos preditivos quanto à sua qualidade, que possam contribuir para reduzir os riscos envolvidos na sua exploração. / Diagenetic processes control the porosity and permeability of petroleum reservoirs. A systematic study of 71 sandstones and conglomerates of the Itabapoana Formation (Aptian), selected from the cores of 13 wells in the offshore portion of Campos Basin, eastern Brazil, allowed the recognition of the main primary and diagenetic constituents, pore types, and of the space and time relations among them. These rocks are contemporaneous to the extensive lacustrine Pre-Salt carbonate reservoirs under exploration. The rocks range from very fine-grained sandstones to conglomerates, with predominance of very coarse-grained sandstones, and their original detrital composition corresponds to lithic arkoses and feldspathic litharenites, rich in volcanic rock fragments (VFR). Smectitic clay minerals are the most abundant diagenetic constituents, related mostly to the alteration of VRF, heavy minerals and biotite. The burial and thermal history and the flow of fluids also exerted a fundamental role on the diagenetic processes and on the of reservoir quality. The main diagenetic processes recorded were the dissolution of volcanic fragments, feldspars and heavy minerals, the authigenesis of smectites, hematite, dolomite, calcite, zeolites and titanium oxides in intergranular pores and replacing VRF, feldspars, biotite and heavy minerals, mechanical and chemical compaction, and the albitization of feldspars, mostly plagioclase. Primary intergranular porosity was strongly reduced by compaction and smectite, calcite, dolomite and zeolite cementation. On the other hand, secondary porosity was generated by the dissolution of primary and diagenetic constituents, and by fracturing. Future specific and detailed studies, including electron microscopy, X-ray diffraction and stable isotope analyses, shall contribute to a better understanding of the space and time distribution of diagenetic processes in these rocks, in order to support the development of predictive models of their quality that may contribute to the reduction of risks involved in their exploration.
26

Diagênese de arenitos e conglomerados aptianos da Bacia de Campos

Carvalho, Awilsa de Souza Gonçalves January 2014 (has links)
Processos diagenéticos controlam a porosidade e permeabilidade dos reservatórios de petróleo. Um estudo petrográfico sistemático de 71 arenitos e conglomerados da Formação Itabapoana (Aptiano), selecionadas de testemunhos de 13 poços na porção offshore da Bacia de Campos, Leste do Brasil, permitiu o reconhecimento dos principais constituintes primários, diagenéticos, tipos de poros e das relações temporais e espaciais entre eles. Essas rochas são contemporâneas aos extensos reservatórios lacustres do “Pré-Sal” atualmente em exploração. As rochas variam de arenitos muito finos a conglomerados, com predominância de arenitos muito grossos, e sua composição detrítica original corresponde a arcósios líticos e litarenitos feldspáticos, ricos em fragmentos de rochas vulcânicas (FRV). Argilominerais esmectíticos são os mais abundantes constituintes diagenéticos, relacionados principalmente à alteração de FRV, minerais pesados e biotita. A história térmica e de soterramento, e o fluxo de fluídos também exerceram um papel fundamental nos processos diagenéticos e na evolução da qualidade de reservatório. Os principais processos diagenéticos registrados foram a dissolução de FRV, feldspatos e minerais pesados, a autigênese de esmectitas, hematita, dolomita, calcita, zeolitas e óxidos de titânio cimentando e substituindo FRV, feldspatos, biotita e minerais pesados, a compactação mecânica e química, e a albitização dos feldspatos, principalmente dos plagioclásios. A porosidade primária intergranular foi fortemente reduzida pela compactação e cimentação por argilominerais esmectíticos, calcita, dolomita e zeolitas. Por outro lado, porosidade secundária foi gerada pela dissolução de constituintes primários e diagenéticos, e por faturamento. Futuros estudos específicos e detalhados, incluindo análises de microscopia eletrônica, difratometria de raios-X e isótopos estáveis, deverão contribuir para um melhor entendimento da distribuição espacial e temporal dos processos diagenéticos nessas rochas, de modo a embasar o desenvolvimento de modelos preditivos quanto à sua qualidade, que possam contribuir para reduzir os riscos envolvidos na sua exploração. / Diagenetic processes control the porosity and permeability of petroleum reservoirs. A systematic study of 71 sandstones and conglomerates of the Itabapoana Formation (Aptian), selected from the cores of 13 wells in the offshore portion of Campos Basin, eastern Brazil, allowed the recognition of the main primary and diagenetic constituents, pore types, and of the space and time relations among them. These rocks are contemporaneous to the extensive lacustrine Pre-Salt carbonate reservoirs under exploration. The rocks range from very fine-grained sandstones to conglomerates, with predominance of very coarse-grained sandstones, and their original detrital composition corresponds to lithic arkoses and feldspathic litharenites, rich in volcanic rock fragments (VFR). Smectitic clay minerals are the most abundant diagenetic constituents, related mostly to the alteration of VRF, heavy minerals and biotite. The burial and thermal history and the flow of fluids also exerted a fundamental role on the diagenetic processes and on the of reservoir quality. The main diagenetic processes recorded were the dissolution of volcanic fragments, feldspars and heavy minerals, the authigenesis of smectites, hematite, dolomite, calcite, zeolites and titanium oxides in intergranular pores and replacing VRF, feldspars, biotite and heavy minerals, mechanical and chemical compaction, and the albitization of feldspars, mostly plagioclase. Primary intergranular porosity was strongly reduced by compaction and smectite, calcite, dolomite and zeolite cementation. On the other hand, secondary porosity was generated by the dissolution of primary and diagenetic constituents, and by fracturing. Future specific and detailed studies, including electron microscopy, X-ray diffraction and stable isotope analyses, shall contribute to a better understanding of the space and time distribution of diagenetic processes in these rocks, in order to support the development of predictive models of their quality that may contribute to the reduction of risks involved in their exploration.
27

Lateral Facies Trends in Deep-Marine Slope and Basin Floor Matrix-Rich Beds, Neoproterozoic Windermere Supergroup, British Columbia, Canada

Angus, Katrina January 2016 (has links)
This study investigates the lithological characteristics, and lateral and vertical facies trends of poorly understood, deep-marine matrix-rich sedimentary rocks. Two laterally extensive, well-exposed outcrops of slope and proximal basin floor deposits were investigated from the Neoproterozoic Windermere Supergroup. Significantly, matrix-rich beds have been found to undergo the same lateral trends (over ~200-650 m) in both outcrops. Initially, thicker, clayey sandstone transitions laterally to a bipartite bed with the development of an upper, planar-based, more matrix-rich unit. Further laterally, the basal unit progressively thins until it pinches out, and all that remains is the upper, more matrix-rich unit – a sandy claystone. It too thins and then pinches out. Draping the entire transect is a thin, matrix-poor structured unit overlain by a mudstone or claystone cap. These trends are interpreted to reflect a progressive but rapid lateral evolution of flow structure controlled primarily by particle settling, namely sand, from mud-rich avulsion-related flows.
28

Storm- and Tide-Dominated Shoreface Deposits, Milk River Formation (Upper Cretaceous), Southern Alberta

Clarke McCrory, Vernon Leslie 04 1900 (has links)
<p> Several sections of the Milk River Formation were measured and studied in detail at Writing on Stone Provincial Park in Southern Alberta. The observed vertical facies succession consists of, from base to top: 1) interbedded, sharp-based sandstones and bioturbated shales; 2) dominantly swaley cross-stratified sandstones; 3) dominantly cross-bedded sandstones; 4) non-marine shales and various thin sandstone and lignite interbeds; 5) local, non-marine cross-bedded sandstones.</p> <p> The sharp-based sandstones have been episodically emplaced on top of offshore muds. The dominantly swaley cross-stratified sandstone is a storm-dominated shoreface deposit in which fairweather deposits (eg. medium scale cross-bedding), are rarely preserved. The cross-bedded sandstones record deposition in tidally-influenced estuaries which cut into beach and shoreface deposits. The section is capped by vertically accreted muds and thin lignite seams which represent floodplain and terrestrial deposition landwards of the strandline. The non-marine cross-bedded sandstones are local representatives of fluvial channel deposits.</p> <p> Paleoflow directions measured in the cross-bedded sandstones indicate that the regional strandline was oriented southwest - northeast at Writing on Stone.</p> <p> Petrographic analysis of the swaley cross-stratified and cross-beddedm sandstones indicate that they are Subarkoses. A definite upward coarsening trend from fine to medium grained quartz is observed in the main sandstone body.</p> / Thesis / Bachelor of Science (BSc)
29

Petrography and Provenance of an Archean Conglomerate Manitou Lake Northwestern Ontario

Teal, Suzanne E. 05 1900 (has links)
<p> The Archean "Loose Pebble Bay" conglomerate, Manitou Lake, northwestern Ontario, contains a variety of clast types, not all of which can be readily ascribed to local lithologies. This study was undertaken to determine the modal clast composition of the conglomerate, and investigate the origin of the clasts. The conglomerate lies near the top of a stratigraphic sequence which includes mafic and felsic volcanic rocks, iron formations, conglomerates, sandstones and argillites. The conglomerate unit itself consists of interbedded conglomerate and sandstone, and probably represents a channel-fill deposit of an ancient submarine fan.</p> <p> Modal percentages of clast types were obtained using a line-intercept method. They indicate that most of the debris in the conglomerate can be reasonably attributed to uplift and erosion of the lateral equivalents of the underlying stratigraphy, except for the granitoid clasts, which have no known origin within the area.</p> <p> Petrographic examinations of the clasts indicate that field identifications must be confirmed with thin section investigations.</p> <p> The modal composition of granitoid clasts was determined utilizing both thin sections and stained slabs. Most of the granitoid clasts are granodiorite, or lie just within the granite field, adjacent to the granodiorite field. Textural studies of the granitoid clasts suggest that gneissic and allotriomorphic-granular textured rocks may have formed by deformation or partial recrystallization along grain boundaries of previously hypidiomorphic-granular rocks. Textures generally indicate intrusive origin and slow cooling, although two granophyric samples may have solidified at relatively shallower depths than the other granitoid rocks.</p> <p> The textures and compositions of most of the granitoid clasts suggest that they were derived from one intrusive body. Intrusion of such a body into the volcanic-sedimentary belt, followed by uplift and erosion, would account for the presence in the "Loose Pebble Bay" conglomerate of granitic clasts and clasts similar to the underlying rocks. However, no evidence of such an intrusion has been found in the Manitou Lake area, and two of the granitoid clasts are noticeably different in composition from the others. The possibility of a pre-existing sialic basement cannot be ruled out.</p> / Thesis / Bachelor of Science (BSc)
30

Caractérisation architecturale haute-résolution des lobes turbiditiques sableux confinés : exemple de la formation des Grès d'Annot (Eocène-Oligocène, SE France). / High-resolution architectural characterization of sand-rich confined turbidite lobes : Examples from the Annot Sandstone Formation (Eocene-Oligocene, SE France)

Etienne, Samuel 13 December 2012 (has links)
La formation Eocène-Oligocène des Grès d’Annot constitue le remplissage gravitaire syntectonique de bassins d’avant-pays complexes, développés au front de l'orogène alpin. Les dépôts relativement distaux de ce système turbiditique s'apparentent à des lobes sous-marins. Ces corps sableux sont caractérisés par une géométrie tabulaire et isopaque à l’échelle pluri-kilométrique. Ce travail met cependant en évidence une extrême complexité dans la répartition des faciès, structures et figures sédimentaires, en lien avec une grande variabilité des processus de transport/dépôt. Ceux-ci sont à l’origine d'objets élémentaires à la géométrie et aux remplissages distincts. Cette forte variabilité sédimentaire implique d'importantes hétérogénéités pouvant influencer la circulation des fluides sur des systèmes réservoirs analogues. A titre de comparaison, une étude complémentaire est effectuée sur un système gravitaire carbonaté (Formation Guwayza, Jurassique moyen, Nord de l’Oman), en contexte de marge passive, afin de discuter de l’importance relative des processus à l’égard du contexte géodynamique sur la variabilité des lobes. / The siliciclastic Annot Sandstones formation (SE France) is composed of a thick series of gravitary deposits and represents the Late Eocene to Early Oligocene northward infill by various types of gravitary deposits of relatively small foreland basins developed in front of the Alpine orogen. This study brings new quantitative data on the terminal deposits of this turbidite system (sand-rich lobes) and focuses on their internal architecture from depositional event scale to elementary object scale. A longitudinal distribution model of elementary objects (from proximal vertically stacked channelized lobes to distal tabular lobes) and associated heterogeneities has been established. Those features have not been accurately described in sand-rich turbidite deposits so far. This high internal variability necessarily implies heterogeneities in terms of petrophysical characteristics (porosity, permeability) and reservoir connection that may have a significant impact on fluid circulation. As a comparison, a similar study on calciturbidites sheet-like lobes from the Middle Jurassic Guweyzah Formation of North Oman is introduced. These results allow reconsidering both sedimentary processes involved in sand-rich lobes and also reservoir models that can be established on field analogues.

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