<p>Petrophysical evaluation of the Albian age gas bearing sandstone reservoirs of the O-M field, Offshore South Africa has been performed. The main goal of the thesis is to evaluate the reservoir potentials of the field through the integration and comparison of results from core analysis, production data and petrography studies for the evaluation and correction of key petrophysical parameters from wireline logs which could be used to generate an effective reservoir model. A total of ten wells were evaluated and twenty eight sandstone reservoirs were encountered of which twenty four are gas bearing and four are wet within the Albian age depth interval of 2800m to 3500m. Six lithofacies (A1, A2, A3, A4, A5 and A6) were grouped<br /> according to textural and structural features and grain size from the key wells (OP1, OP2 and OP3). Facies A6 was identified as non reservoir rock in terms of reservoir rock quality and facies A1 and A2 were regarded as the best reservoir rock quality. This study identifies the different<br /> rock types that comprise reservoir and non reservoirs. Porosity and permeability are the key parameters for identifying the rock types and reservoir characterization. Pore throat radius was estimated from conventional core porosity and permeability with application of the Winland&rsquo / s method for assessment of reservoir rock quality on the bases of pore throat radius. Results from the Winland&rsquo / s method present five Petrofacies (Mega porous, Macro porous, Meso porous, Micro porous and Nanno porous). The best Petrofacies was mega porous rock type which corresponds to lithofacies A1 and A2. The nano porous rock type corresponds to lithofacies A6 and was subsequently classified as non reservoir rock. The volume of clay model from log was taken from the gamma-ray model corrected by Steiber equations which was based on the level of agreement between log data and the x-ray diffraction (XRD) clay data. The average volume of clay determined ranged from 1 &ndash / 28 %. The field average grain density of 2.67 g/cc was determined from core data which is representative of the well formation, hence 2.67 g/cc was used to estimate porosity from the density log. Reservoir rock properties are generally good with reservoir average porosities between 10 &ndash / 22 %, an average permeability of approximately 60mD. The laterolog resistivity values have been invasion corrected to yield estimates of the true formation resistivity. In general, resistivities of above 4.0 Ohm-m are productive reservoirs, an average water resistivity of 0.1 Ohm-m was estimated. Log calculated water saturation models were calibrated with capillary pressure and conventional core determined water saturations, and the Simandoux shaly sand model best agree with capillary and conventional core water saturations and was used to determine field water saturations. The reservoir average water saturations range between 23 &ndash / 69 %. The study also revealed quartz as being the dominant mineral in addition to abundant chlorite as the major clay mineral. The fine textured and dispersed pore lining chlorite mineral affects the reservoir quality and may be the possible cause of the low resistivity recorded in the area. The reservoirs evaluated in the field are characterized as normally pressured with an average reservoir pressure of 4800 psi and temperature of 220 &ordm / F. An interpreted field aquifer gradient of 0.44 psi/ft (1.01 g/cc) and gas gradient of 0.09 psi/ft (0.2 g/cc) were obtained from repeat formation test measurements. A total of eight gas water contacts were identified in six wells. For an interval to be regarded as having net pay potential, cut-off values were used to distinguish between pay and non-pay intervals. For an interval to be regarded as pay, it must have a porosity value of at least 10 %, volume of clay of less than 40 %, and water saturation of not more than 65 %. A total of twenty four reservoir intervals meet the cut-off criteria and was regarded as net pay intervals. The gross thickness of the reservoirs range from 2.4m to 31.7m and net pay interval from 1.03m to 25.15m respectively. In summary, this study contributes to scale transition issues in a complex gas bearing sandstone reservoirs and serves as a basis for analysis of petrophysical properties in a multi-scale system.</p>

<p>Petrophysical evaluation of the Albian age gas bearing sandstone reservoirs of the O-M field, Offshore South Africa has been performed. The main goal of the thesis is to evaluate the reservoir potentials of the field through the integration and comparison of results from core analysis, production data and petrography studies for the evaluation and correction of key petrophysical parameters from wireline logs which could be used to generate an effective reservoir model. A total of ten wells were evaluated and twenty eight sandstone reservoirs were encountered of which twenty four are gas bearing and four are wet within the Albian age depth interval of 2800m to 3500m. Six lithofacies (A1, A2, A3, A4, A5 and A6) were grouped<br /> according to textural and structural features and grain size from the key wells (OP1, OP2 and OP3). Facies A6 was identified as non reservoir rock in terms of reservoir rock quality and facies A1 and A2 were regarded as the best reservoir rock quality. This study identifies the different<br /> rock types that comprise reservoir and non reservoirs. Porosity and permeability are the key parameters for identifying the rock types and reservoir characterization. Pore throat radius was estimated from conventional core porosity and permeability with application of the Winland&rsquo / s method for assessment of reservoir rock quality on the bases of pore throat radius. Results from the Winland&rsquo / s method present five Petrofacies (Mega porous, Macro porous, Meso porous, Micro porous and Nanno porous). The best Petrofacies was mega porous rock type which corresponds to lithofacies A1 and A2. The nano porous rock type corresponds to lithofacies A6 and was subsequently classified as non reservoir rock. The volume of clay model from log was taken from the gamma-ray model corrected by Steiber equations which was based on the level of agreement between log data and the x-ray diffraction (XRD) clay data. The average volume of clay determined ranged from 1 &ndash / 28 %. The field average grain density of 2.67 g/cc was determined from core data which is representative of the well formation, hence 2.67 g/cc was used to estimate porosity from the density log. Reservoir rock properties are generally good with reservoir average porosities between 10 &ndash / 22 %, an average permeability of approximately 60mD. The laterolog resistivity values have been invasion corrected to yield estimates of the true formation resistivity. In general, resistivities of above 4.0 Ohm-m are productive reservoirs, an average water resistivity of 0.1 Ohm-m was estimated. Log calculated water saturation models were calibrated with capillary pressure and conventional core determined water saturations, and the Simandoux shaly sand model best agree with capillary and conventional core water saturations and was used to determine field water saturations. The reservoir average water saturations range between 23 &ndash / 69 %. The study also revealed quartz as being the dominant mineral in addition to abundant chlorite as the major clay mineral. The fine textured and dispersed pore lining chlorite mineral affects the reservoir quality and may be the possible cause of the low resistivity recorded in the area. The reservoirs evaluated in the field are characterized as normally pressured with an average reservoir pressure of 4800 psi and temperature of 220 &ordm / F. An interpreted field aquifer gradient of 0.44 psi/ft (1.01 g/cc) and gas gradient of 0.09 psi/ft (0.2 g/cc) were obtained from repeat formation test measurements. A total of eight gas water contacts were identified in six wells. For an interval to be regarded as having net pay potential, cut-off values were used to distinguish between pay and non-pay intervals. For an interval to be regarded as pay, it must have a porosity value of at least 10 %, volume of clay of less than 40 %, and water saturation of not more than 65 %. A total of twenty four reservoir intervals meet the cut-off criteria and was regarded as net pay intervals. The gross thickness of the reservoirs range from 2.4m to 31.7m and net pay interval from 1.03m to 25.15m respectively. In summary, this study contributes to scale transition issues in a complex gas bearing sandstone reservoirs and serves as a basis for analysis of petrophysical properties in a multi-scale system.</p>

Philosophiae Doctor - PhD / Petrophysical evaluation of the Albian age gas bearing sandstone reservoirs of the O-M field, Offshore South Africa has been performed. The main goal of the thesis is to evaluate the reservoir potentials of the field through the integration and comparison of results from core analysis, production data and petrography studies for the evaluation and correction of key petrophysical parameters from wireline logs which could be used to generate an effective reservoir model. A total of ten wells were evaluated and twenty eight sandstone reservoirs were encountered of which twenty four are gas bearing and four are wet within the Albian age depth interval of 2800m to 3500m. Six lithofacies (A1, A2, A3, A4, A5 and A6) were grouped according to textural and structural features and grain size from the key wells (OP1, OP2 and OP3). Facies A6 was identified as non reservoir rock in terms of reservoir rock quality and facies A1 and A2 were regarded as the best reservoir rock quality. This study identifies the different rock types that comprise reservoir and non reservoirs. Porosity and permeability are the key parameters for identifying the rock types and reservoir characterization. Pore throat radius was estimated from conventional core porosity and permeability with application of the Winland’s method for assessment of reservoir rock quality on the bases of pore throat radius. Results from the Winland’s method present five Petrofacies (Mega porous, Macro porous, Meso porous, Micro porous and Nanno porous). The best Petrofacies was mega porous rock type which corresponds to lithofacies A1 and A2. The nano porous rock type corresponds to lithofacies A6 and was subsequently classified as non reservoir rock. The volume of clay model from log was taken from the gamma-ray model corrected by Steiber equations which was based on the level of agreement between log data and the x-ray diffraction (XRD) clay data. The average volume of clay determined ranged from 1 – 28 %. The field average grain density of 2.67 g/cc was determined from core data which is representative of the well formation, hence 2.67 g/cc was used to estimate porosity from the density log. Reservoir rock properties are generally good with reservoir average porosities between 10 – 22 %, an average permeability of approximately 60mD. The laterolog resistivity values have been invasion corrected to yield estimates of the true formation resistivity. In general, resistivities of above 4.0 Ohm-m are productive reservoirs, an average water resistivity of 0.1 Ohm-m was estimated. Log calculated water saturation models were calibrated with capillary pressure and conventional core determined water saturations, and the Simandoux shaly sand model best agree with capillary and conventional core water saturations and was used to determine field water saturations. The reservoir average water saturations range between 23 – 69 %. The study also revealed quartz as being the dominant mineral in addition to abundant chlorite as the major clay mineral. The fine textured and dispersed pore lining chlorite mineral affects the reservoir quality and may be the possible cause of the low resistivity recorded in the area. The reservoirs evaluated in the field are characterized as normally pressured with an average reservoir pressure of 4800 psi and temperature of 220 ºF. An interpreted field aquifer gradient of 0.44 psi/ft (1.01 g/cc) and gas gradient of 0.09 psi/ft (0.2 g/cc) were obtained from repeat formation test measurements. A total of eight gas water contacts were identified in six wells. For an interval to be regarded as having net pay potential, cut-off values were used to distinguish between pay and non-pay intervals. For an interval to be regarded as pay, it must have a porosity value of at least 10 %, volume of clay of less than 40 %, and water saturation of not more than 65 %. A total of twenty four reservoir intervals meet the cut-off criteria and was regarded as net pay intervals. The gross thickness of the reservoirs range from 2.4m to 31.7m and net pay interval from 1.03m to 25.15m respectively. In summary, this study contributes to scale transition issues in a complex gas bearing sandstone reservoirs and serves as a basis for analysis of petrophysical properties in a multi-scale system. / South Africa

The biostratigraphy and isotope stratigraphy of the upper Aptian to lower Cenomanian interval including oceanic anoxic events OAE1b, 1c and 1d are investigated in ODP Site 763, drilled on the Exmouth Plateau offshore northwest Australia. Benthic foraminifera suggest that Site 763 was situated in outer neritic to upper bathyal water depths (~150-600 m). OAEs of the Atlantic basin and Tethys are typically associated with organic carbon-rich black shales and δ13C excursions. However, OAEs at this high latitude site correlate with ocean acidification and/or pyrite formation under anoxic conditions rather than black shales. Ocean acidification maybe responsible for sporadic low abundances of planktic foraminifera compared to radiolarians and benthic foraminifera associated with increased volcanogenic CO2 production during the formation of the Southern and Central Kerguelen Plateaus. Sea surface temperature may have cooled to 11°C in the late Aptian but increased gradually during the Albian. The Aptian/Albian boundary is placed at a negative carbon isotope excursion associated with the lowest occurrence of Microhedbergella renilaevis, typically found within the Niveau Kilian black shale of OAE1b. Third-order sea level cycles, particularly in the middle Albian, produced cyclic changes in the abundance of inoceramid prisms that increased during inferred times of falling sea level. The late Albian OAE1c and OAE1d coincide with horizons of intense pyritization and the absence of all biocomponents suggesting the development of euxinia. Warm Tethyan waters reached the Exmouth Plateau during the latest Albian based on the presence of thermocline dwelling keeled planktic foraminifera including Planomalina buxtorfi.

No description available.

The Mural Limestone, located in the Mule Mountains to the northeast and southeast of Bisbee, Arizona provides an exceptional outcrop analog for time-equivalent productive reservoirs in the Albian Glen Rose patch-reef play of the Maverick Basin. The Mural Limestone is exposed in a number of folds and east-dipping fault blocks in the Grassy Hill and Paul Spur localities in the Mule Mountains and represents a remnant of a south-facing distally-steepened carbonate ramp that prograded into the Chihuahua Trough in Albian time. This study documents the detailed facies architecture and sequence stratigraphic setting of a multicyclic patch-reef and its associated ramp interior facies at the Paul Spur and Grassy Hill localities, respectively. Small mud-dominated coral-algal buildups (~5 m thick) and tabular biostromes (up to 1.5 m thick) consisting of rudist floatstones are common in the bedded ramp interior carbonates at the Grassy Hill locality in the Mule Mountains 10 km landward of the Paul Spur reef. Buildups in this area are flanked by weakly-cyclic and well-bedded skeletal mud- and grain-dominated packstones. At the Paul Spur locality, Mural facies consist of a 10-35 m thick patch-reef with four distinct reef communities: microbial-Microsolena framestone, algal-Actinastrea boundstone, branching coral-skeletal framestone and caprinid-requienid floatstone. Measured reef dimensions show a distinct windward-leeward margin with reef frame facies extending ~70 m from the margin and extensive leeward rudstone debris and grainstone shoal facies extending a distance of 870 m. Reef and backreef shoal facies exhibit low preserved porosity but petrographic analysis of backreef grainstones shows that primary porosity and permeability was present. These extensive reservoir-prone shoals may be a suitable reservoir target similar to flank rudstones and grainstones of the Maverick Basin reefs. Three aggradational to retrogradational cycles of reef growth are evident at the Paul Spur locality. Retrogradational stacking is consistent with that of time-equivalent Lower Glen Rose patch-reefs in the Maverick Basin of Texas, which suggests a eustatic driver for stratigraphic architecture along the Bisbee/Comanche shelf. Backstepping of reef frame facies in Cycle 3 is interpreted to be time-equivalent to patch-reef development at the Grassy Hill locality. / text

L’intervalle Aptien-Albien inférieur de la marge sud-téthysienne est mal connu en raison de successions souvent incomplètes et de difficultés à les dater. Le Bassin d’Essaouira-Agadir (BEA), au Maroc, présente de nombreuses coupes, bien exposées et accessibles du Crétacé inférieur. Le but de ce travail est de (1) établir un cadre stratigraphique intégré de la série apto-albienne, basé sur (a) la biostratigraphy haute résolution des ammonites et des nannofossiles calcaires, (b) l’identification des discontinuités sédimentaires et (c) la stratigraphy isotopique du carbone; (2) reconstituer l’évolution paléoenvironnementale pendant cet intervalle, par l’étude des facies sédimentaires et l’analyse qualitative et quantitative des nannofossiles, et (3) proposer un modèle de fonctionnement de la plateforme-rampe mixte, carbonate-clastique, du BEA.Dans le BEA, le Barrémien supérieur est défini par la zone d’ammonites à sarasini et par la zone de nannofossiles NC5. La limite Barrémien-Aptien est définie par les ammonites. L’Aptien inférieur est déterminé par les zones d’ammonites à desahayesi jusqu’à furcata, et est limité par un premier minimum de 13C à la base, et par un premier maximum à la limite Aptien inférieur-moyen. L’Aptien supérieur est défini par quatre zones d’ammonites (martini, melchioris, nolani et jacobi), deux surfaces de discontinuité, quatre maxima et minima de 13C, et comprend la partie supérieure de NC6, NC7 et la base de NC8. La limite Aptien-Albien est placée dans la discontinuité D4 (base de la zone d’ammonites à Leymeriella tardefurcata), en accord avec la première occurrence (FO) des nannofossiles Prediscosphaera columnata et Hayesites albiensis, et par une diminution des valeurs de 13C. L’Albien inférieur est daté par les zones d’ammonites à tardefurcata et mammillatum, par la FO du nannofossile Hayesites albiensis, et par des valeurs minimales de 13C.Les faciès et environnements de dépôt des sédiments aptien à Albien inférieur ont été déterminés par leur lithologie, les figures sédimentaires, leur contenu faunique et les microfaciès. Ils ont permis d’identifier (1) quatre types de surface liées à des érosions subaériennes ou sous-marines, (2) quatre faciès sédimentaires carbonatés dans l’Aptien, correspondant à des environnements de rampe interne à distale, et (3) quatre faciès sédimentaires argilo-gréseux dans l’Albien inférieur, représentant des dépôts de rampe médiane à hémipélagiques. Ces faciès reflètent des milieux adjacents et passant de l’un à l’autre. L’intervalle Aptien-Albien inférieur du BEA a été subdivisé en deux cycles, soulignés par deux surfaces d’érosion majeures. Le cycle Barrémien terminal-Aptien est souligné par une surface karstifiée et erosive et comprend quatre séquences de dépôt de troisème ordre. Le cycle Albien surmonte une surface majeure d’érosion sous-marine, et contient au moins quatre sequences de dépôt. Dasns chaque cycle, l’évolution vertical des faciès indique un approfondissement ds milieux de depot liée à une hausse eustatique.Dans le BEA, production carbonatée est plus élevée à l’Aptien qu’à l’Albien inférieur, en raison d’un climat chaud, une lente montée du niveau de la mer, un milieu de dépôt peu profond et de faibles apports détritiques. L’abondance totale absolue des nannofossiles décroît entre l’Aptien et l’Albien inférieur, en raison d’un taux de sedimentation plus élevé associé à une subsidence plus rapide. L’apport en nutriments, la fertilité et la production primaire sont plus élevés à l’Albien inférieur qu’à l’Aptien, et sont principalement contrôlés par la montée du niceau de la mer et les courants d’upwellings. La transition Aptien terminal-Albien inférieur est marquée par l’abondance de taxons d’eau froide et par la migration de faunes cosmopolitaines du domaine boréal vers le domaine téthysien, qui pourrait traduire un événement climatique froid, voire glaciaire. / The Aptian-Early Albian interval of the southern Tethyan margin is poorly understood since sedimentary successions are frequently incomplete and dating is difficult. The Essaouira-Agadir Basin (EAB), Morocco, presents numerous, very good and accessible outcrops of the Early Cretaceous series. The aim of this work is to (1) establish an integrated stratigraphic framework of the Aptian-Albian series based on (a) high-resolution ammonites and calcareous nannofossil biostratigraphy, (b) identification of sedimentary discontinuities and (c) carbon isotope stratigraphy; (2) reconstruct the paleoenvironmental evolution during this interval through both sedimentary facies evolution and qualitative and quantitative nannofossil analyses, and (3) propose a functioning model for the sedimentation on the mixed, carbonate/clastic ramp of the EAB.In the EAB, the Late Barremian is defined by the sarasini ammonite zone and the NC5 nannofossil zone. The Barremian/Aptian boundary is defined by ammonites. The Early Aptian is defined by the deshayesi to furcata ammonite zones, and is bounded by a first minimum 13C value at the base and a first maximum value at the Early/Late Aptian Boundary. The Late Aptian interval, is defined by four ammonite zones (martini, melchioris, nolani and jacobi), two discontinuity surfaces, four maximum and minimum 13C values, and by the upper part of the NC6, the NC7 and the lowermost part of the NC8 nannofossil zones. The Aptian/Albian boundary is placed within the discontinuity D4 (base of the Leymeriella tardefurcata ammonite zone), supported by the First Occurrence (FO) of the Prediscosphaera columnata and Hayesites albiensis nannofossil taxa, and by decreasing 13C values. Early Albian times are represented by the tardefurcata and mammillatum ammonite zones, the FO of Hayesites albiensis, and by minimum 13C values.The facies and depositional environments of the Aptian-Early Albian rocks are identified based on their lithology, sedimentary structures, fossil content and microfacies. These allowed to identify (1) four types of key surfaces related subaerial or submarine erosion, (2) four sedimentary carbonated facies in the Aptian corresponding to outer to inner ramp depositional environments, and (3) four Early Albian sedimentary facies, represented by sandstones and shales, of basin to middle ramp depositional setting. These facies reflect deposition in adjacent and gradational paleoenvironments. The Aptian-Early Albian stratigraphic interval of the EAB, has been subdivided into two major cycles, floored by two major erosional surfaces. The latest Barremian-Aptian cycle is underlined by a major karstified-erosional surface and consists of four third-order depositional sequences. The Early Albian cycle, overlies a major submarine erosional surface, and also contains four depositional sequences. In each cycle, the vertical changes in facies indicates a deepening upward trend related to sea level rise.The carbonate production in the EAB is higher in the Aptian than during the Early Albian, due to warm conditions, slow rise of sea level, shallow depth of the basin, and little detrital influx. The nannofossil total absolute abundance decreases from the Aptian to the Early Albian, due to increasing sedimentation rate, associated with rapid subsidence. The nutrient input, fertility and calcareous nannofossil primary productivity is higher in the Early Albian with respect to the Aptian, and are mainly controlled by rising sea level and upwelling currents. The Latest Aptian-Early Albian period is characterized by a high abundance of cold taxa, and the migration of cosmopolitan biota from Boreal realm into the Tethyan realm, which may reflect the occurrence of a glacial climatic event.

L'objectif initial de cette thèse consistait à fournir un analogue de terrain de réservoirs pétroliers avec un modèle 3D des structures et de l'architecture des sédiments développés sur la bordure d'un basin étroit et confiné. La zone d'étude, située entre Bakio et Plenzia (Pays Basque, Espagne), appartient au fossé Basque, souvent interprété comme un basin en pull-apart. Nous avons focalisé ce travail sur le diapir de Bakio, sur les modalités de la montée du sel, sa chronologie et sur l'impact de la tectonique salifère sur sédimentation et la déformation des sédiments environnants. Un éventail sédimentaire composé de dépôts albiens, avec un amincissement vers le diapir montre la monté synsédimentaire du sel. Nous démontré l'existence d'une première phase de montée du sel réactive puis une seconde phase passive. La phase réactive est expliquée par l'extension régionale. Durand le stade passive, des séquences halokinetiques, qui résultent de variations entre la monté du sel et le taux de sédimentation, ont été formées. Nos données montre qu'une grande partie de la déformation est due à la rotation des flancs du diapir et non à un cisaillement significatif induit par la montée su sel. Nous avons aussi concentré ce travail sur les structures albiennes de notre zone d'étude. La comparaison avec l'ensemble du Bassin Basco Cantabrien montre deux stades d'activation des failles. De l'Aptien à l'Albien moyen, les nombreuses failles orientées NE-SO, largement distribuées,contrôlaient les plates formes urgoniennes et les fossés marneux associés. Quelques failles majeures héritées, orientées NO-SE contrôlaient aussi les dépocentres surtout dans la partie centrale du Basin Basco-Cantabrien. Ce premier stage est interprété comme le résultat d'un extension NO-SE. De l'Albien moyen à supérieur, la déformation était localisée essentiellement le long de la faille Guernika-Elgoibar, orientée NO-SE, qui contrôle un bassin asymétriques, étroit et allongé remplis par les Flyschs Noirs. Durant le second stage, les dépocentres du Flysch Noir sont interprétés comme des bassins en transtension et non en pull-apart, car une seule faille majeure contrôlait ces basins asymétriques. / The initial purpose of this thesis was to provide a field analogue for petroleum reservoirs with a 3D model of the main structures and of the architecture of deposits developed on the border of a narrow and confined basin. The study area, located between Bakio and Plenzia (Basque Country, Spain), belongs to the Basque Trough, commonly interpreted as a pull-apart basin. We focused on the Bakio diapir, which allows a discussion of the modalities of salt rising, its chronology and of the impacts of salt on the overburden deformation and on sedimentation. A well exposed wedge-shaped structure composed of Albian deposits, with thinning toward the diapir documents synsedimentary salt rising. We showed that the diapir rose firstly as a reactive diapir in response to regional extension and then as a passive diapir. During the passive stage, halokinetic sequences developed, induced by variations of the ratio between net salt rising and net sedimentation rate. All our data from the Bakio diapir show that an important part of deformation is related to diapir flank rotation and not to significant shear associated with salt rising. We also focused on the Albian structural geology in our study area. The comparison of the local Albian fault system with faults from the whole Basque-Cantabrian Basin emphasizes two stages of faults activity. From Aptian to Early-Middle Albian, widely distributed NE-SW striking faults controlled the development of the Urgonian platforms and associated marly troughs. Some major inherited NW-SE striking faults also controlled the localization of depocenters, especially in the central part of the Basque-Cantabrian Basin. The first stage is assumed to result of a NW-SE extension. From Middle to Late Albian, the deformation localized mainly along the Gernika-Elgoibar fault, striking NW-SE, and controlled the formation of a narrow and elongated asymmetric basin developed, filled by Black Flysch units. During this second stage, Black Flysch depocenter are interpreted to form in transtensional setting and cannot be interpreted as pull-apart basins, as only one major fault controlled asymmetric basins.

Submitted by Luana Fernandes do Nascimento (luanaf_n@yahoo.com.br) on 2016-12-14T18:53:09Z No. of bitstreams: 1 Luana_Unesp_Mestrado_Final.pdf: 15010826 bytes, checksum: d648b060d92f0de0538ad7924f8a3ce0 (MD5) / Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-12-19T17:24:32Z (GMT) No. of bitstreams: 1 nacimento_lf_me_rcla.pdf: 15010826 bytes, checksum: d648b060d92f0de0538ad7924f8a3ce0 (MD5) / Made available in DSpace on 2016-12-19T17:24:32Z (GMT). No. of bitstreams: 1 nacimento_lf_me_rcla.pdf: 15010826 bytes, checksum: d648b060d92f0de0538ad7924f8a3ce0 (MD5) Previous issue date: 2016-10-21 / Outra / A área de estudo corresponde a um campo produtor de hidrocarbonetos situado no sudoeste da Bacia de Campos a 80 km da costa. Esta região produz hidrocarbonetos de diversos níveis estratigráficos, entre eles, os carbonatos do Albiano, foco deste estudo. O alto interesse econômico dos carbonatos no setor petrolífero mundial e a complexidade da sua análise nos dados geofísicos, justifica a importância desta pesquisa na definição de um método que auxilie na caracterização da distribuição regional da propriedade da rocha reservatório, neste caso, a porosidade. Neste contexto, este trabalho objetiva a determinação da heterogeneidade lateral e vertical das propriedades das rochas reservatórios, por meio da construção de um modelo geológico 3D de porosidade dos dois principais reservatórios identificados na Formação Quissamã (Grupo Macaé). Com esta finalidade, o método incluiu seis etapas principais: análise dos perfis geofísicos e correlação de poços, interpretação sísmica, conversão tempo x profundidade, análise de atributos sísmicos, análise geoestatística e modelagem geológica por meio da aplicação de Simulação Sequencial Gaussiana. Como níveis de referência, foram interpretados os intervalos estratigráficos correspondentes à Formação Outeiro e, na Formação Quissamã, os níveis Q1 e reservatórios R1 e R2 (principais produtores do campo). Estes níveis foram definidos com base na mudança do padrão geométrico dos perfis geofísicos de raio gama (RG), densidade (RHOB) e porosidade (Nphi). Os intervalos estudados estão distribuídos em um alto estrutural com eixo principal de direção NW-SE delimitado por falhas e pela própria geometria do banco carbonático. Na porção central do campo, este alto estrutural apresenta valores altos de porosidade (>21%), e se destacou no mapa de resistividade como portador de hidrocarbonetos nos reservatórios R1 e R2. Estas fácies carbonáticas variam para norte e nordeste da área com valores de porosidade mais baixos (<18%), representando a diminuição da qualidade dos reservatórios para estas regiões; esta observação, aliada à influência das falhas a sudoeste e nordeste do banco, permitiu classificar a trapa destes reservatórios como estrutural-estratigráfica. O sistema de falhas predominante na área de estudo corresponde ao NW-SE, que originou estruturas do tipo rollovers e horsts com potencial reservatório. Estas falhas abateram os blocos a sudeste e sul, que foram realçados nos mapas de atributos sísmicos como portadores de alta porosidade, comprovados por gráficos de correlação com coeficiente R2>0,65. Esta análise foi utilizada para determinar o modelo geológico 3D de porosidade, gerado por Simulação Sequencial Gaussiana. O resultado consistiu em uma representação coerente, com maior grau de certeza no alto estrutural central, que possui maior quantidade de dados de poços. Apesar das áreas a sudoeste e sul não apresentarem dados de poços, o método de Simulação Sequencial Gaussiana extrapolou altos valores de porosidade em 23% das 30 realizações geradas. / The study area is an ancient field and hydrocarbon producer, located in the southwest of the Campos Basin, in a water depth of approximately 100 m and 80 km distant from the coast. This region produces hydrocarbon from multiple stratigraphic layers, among them, there are the Albian carbonates, the focus of this research. The high economic interest in carbonates plays by the global oil industry and the complexity of their analysis in geophysical data, justifies the importance of this research to define a method, which determine the regional distribution of the property of the reservoir rock, in this case, the porosity. In this context, this study aims to determine the lateral and vertical heterogeneity of the properties of the reservoir rocks through the construction of a 3D geologic model of porosity from two main reservoirs in Quissamã formation (Macae Group). For this purpose, the method includes six major steps: analysis of well log and correlation of wells, seismic interpretation, conversion time vs. depth, analysis of seismic attributes, geostatistical analysis and geological modeling through the application of Gaussian simulation. The stratigraphic intervals such as Outeiro Formation and Quissamã Formation, which include level Q1, R1 and R2 reservoirs (main producers of the field) were interpreted as reference levels. These intervals were defined based on the change of the geometric standard of the geophysical profiles, as gamma ray (GR), density (RHOB) and porosity (Nphi). These levels are distributed in a carbonate bank with main axis in NW-SE direction, delimited by faults and its geometry. It was observed a structural high in the central portion of the field presenting high porosity values (> 21 %) that was highlighted in the resistivity maps as filled by oil in the reservoirs R1 and R2. These carbonate facies vary to the north and northeast of the area with lower values representing the decline in the quality of the reservoirs for these regions; this observation combined with the influence of the faults , in the southwest and northeast of the bank, allowed to classify the trap of these reservoirs as structural-stratigraphic. The predominant fault system in the study area corresponds to the NW-SE, which formed structures like rollovers and horsts with potential of being reservoir. These faults shot down the block to the southwest and south, which were highlighted in the maps of seismic attributes as having high porosity, supported by cross plots with correlation coefficient of R2> 0.65. This analysis was used to determine the 3D geologic model of porosity, generated by Gaussian simulation, most appropriate to the context of the geological area. The result was a coherent representation with greater certainty in the central structural high that presents a higher amount of well data. Despite the southwest and south areas do not present well data, the method was efficient in interpolate high values of porosity in 23% of 30 generated realizations. / PRH 05: 6000.0082154.13.4

Submitted by William Justo Figueiro (williamjf) on 2015-07-15T20:29:02Z No. of bitstreams: 1 14c.pdf: 18447268 bytes, checksum: cb27bcfcdf1b467b658d2ece3ae7777b (MD5) / Made available in DSpace on 2015-07-15T20:29:02Z (GMT). No. of bitstreams: 1 14c.pdf: 18447268 bytes, checksum: cb27bcfcdf1b467b658d2ece3ae7777b (MD5) Previous issue date: 2012-11-12 / Nenhuma / O presente estudo apresenta a taxonomia, bioestratigrafia e paleoecologia dos foraminíferos planctônicos e bentônicos recuperados no intervalo Aptiano superiorAlbiano da sucessão dominantemente carbonática do Deep Sea Drilling Project (DSDP) Site 364, localizado na bacia de Kwanza (costa afora de Angola). Foram identificadas 30 espécies de foraminíferos planctônicos e 42 espécies de foraminíferos bentônicos. Com base nas assembleias de foraminíferos planctônicos, a seção sedimentar estudada foi subdividida em diversas biozonas, abrangendo as idades Aptiano tardio ao Albiano, da Zona Hedbergella trocoidea a Zona Pseudothalmanninella ticinensis. Uma conspícua discordância foi identificada no core 31, compreendendo do topo do Albiano inferior à base do Albiano superior. A composição específica das assembleias de foraminíferos planctônicos as caracteriza como assembleias marinhas de águas rasas e permite a inferência do domínio de condições mesotróficas a eutróficas ao longo do intervalo estudado. As associações aptianas de foraminíferos planctônicos apresentam afinidade paleobiogeográfica tetiana, suportando um influxo de água superficial tetiana no setor restrito (ao norte da Cadeia de Walvis-Elevação do Rio Grande) do Oceano Atlântico Sul setentrional já no Aptiano tardio. Tendências nos valores isotópicos de 13C, que devem ser cuidadosamente interpretadas devido a uma possível alteração diagenética, sugerem uma idade aptiana tardia (Zona Globigerinelloides algerianus) para o intervalo estratigráfico do core 42 ao core 37, no qual fósseis-guia tetianos estão ausentes, além de sugerir que os folhelhos negros da base do testemunho estudado (cores 42-39) podem ser correlatos ao evento anóxico do Aptiano tardio. Entre os foraminíferos planctônicos ocorre uma profunda mudança faunística na passagem Aptiano-Albiano, caracterizada por altas taxas de extinção seguidas por elevadas taxas de surgimento de espécies, além de uma significativa mudança no padrão arquitetural das testas. Foram identificadas três associações de foraminíferos bentônicos, que parecem ser principalmente controladas por variações paleobatimétricas. A fauna de foraminíferos bentônicos pode ser classificada como uma Associação do tipo Marssonella, provavelmente relacionada a paleoprofundidades neríticas a batiais superiores, e também exibindo uma marcada afinidade paleobiogeográfica tetiana. / This work presents a taxonomic, biostratigraphic and paleoecologic study on the planktic and benthic foraminiferal faunas recovered from the late Aptian-late Albian carbonatedominated succession of Deep Sea Drilling Project (DSDP) Site 364, located in the Kwanza Basin (offshore Angola). Thirty planktic and 42 benthic foraminiferal species were identified herein. Based on planktic foraminiferal assemblages, the studied section was subdivided in a series of biozones, late Aptian to late Albian in age, from the Hedbergella trocoidea Zone to the Pseudothalmanninella ticinensis Zone. A remarkable unconformity was identified in core 31, spanning the latest early to earliest late Albian. The specific composition of the recovered planktic foraminiferal assemblages characterizes them as open marine epipelagic dwellers, and permits the suggestion of predominant mesotrophic to eutrophic environmental conditions throughout the studied stratigraphic succession. Aptian planktic foraminiferal assemblages present a significant Tethyan paleobiogeographic affinity, supporting a Tethyan surface-water influx into this restricted southeastern sector of the northern South Atlantic Ocean (north to the Walvis Ridge-Rio Grande Rise) back in the late Aptian. 13C trends, which have to be carefully interpreted due to possible diagenetic overprint, suggest a late Aptian age (Globigerinelloides algerianus Zone) for the stratigraphic interval from core 42 to about core 37, where Tethyan age-diagnostic foraminiferal species are missing, as well as that the black shale levels in cores 42-39 could be correlated to the “late Aptian anoxic event”. Among planktic foraminifera, a conspicuous faunal turnover occurs at the Aptian/Albian transition, characterized by high rates of extinctions followed by increasing rates of species originations and changes in tests’ architecture. Three benthic foraminiferal associations were identified, which seem to be mainly controlled by changes in paleobathymetry. Also, the studied benthic foraminiferal fauna could be classified as a Marssonella Association, probably related to neritic and upper bathyal paleodepths, also exhibiting a Tethyan paleobiogeographic affinity.