As oil and gas supply decrease, it becomes more important to quantify the uncertainty associated with reservoir models and implementation of field development decisions. Various geostatistical methods have assisted in the development of field scale models of reservoir heterogeneity. Sequential simulation algorithms in geostatistic require an assessment of local uncertainty in an attribute value at a location followed by random sampling from the uncertainty distribution to retrieve the simulation value. Instead of random sampling of an outcome from the uncertainty distrubution, the retrieval of an optimal simulated value at each location by considering an economic loss function is demonstrated in this thesis. By applying a loss function that depicts the economic impact of an over or underestimation at a location and retrieving the optimal simulated value that minimizes the expected loss, a map of simulated values can be generated that accounts for the impact of permeability as it relates to economic loss. Both an asymmetric linear loss function and a parabolic loss function models are investigated. The end result of this procedure will be a reservoir realization that exhibits the correct spatial characteristics (i.e. variogram reproduction) while, at the same time, exhibiting the minimum expected loss in terms of the parameters used to construct the loss function. The process detailed in this thesis provides an effective alternative whereby realizations in the middle of the uncertainty distribution can be directly retrieved by application of suitable loss functions. An extension of this method is to alter the loss function (so as to emphasize either under or over estimation), other realizations at the extremes of the global uncertainty distribution can also be retrieved, thereby eliminating the necessity for the generation of a large suite of realizations to locate the global extremes of the uncertainty distribution. / text

No description available.

No description available.

Iceland straddles the Mid-Atlantic Ridge and overlies a mantle hotspot. This tectonic setting produces voluminous tholeiitic magmas. Volcanism in Iceland is focussed along three neovolcanic spreading ridges. During the Holocene, the Eastern Volcanic Zone (EVZ) in southeast Iceland has been the most volcanically active and has been the site of several large (>6 km3) eruptions, including the only floodbasalt type eruption in recorded history, the 1783-84 Laki eruption. Three eruptions of large volume have been sampled for this study: the 1783-84 Laki eruption (15.1 km3); the 3,000-4,000 yBP Thjórsárdalur eruption (probably >4 km3); and the ~8,600 yBP Thjórsá eruption (>21 km3). The products of these eruptions have been analysed using a range of analytical techniques, with the specific aim of investigating crystallisation, degassing and mixing processes in the magma reservoirs that feed large eruptions. The Laki eruption has been the particular focus of this study. Samples from different parts of the lava flow show fine-scale variations in trace element concentrations and ratios. This compositional variation is not fully explained by fractional crystallisation processes, but is strongly controlled by crystal accumulation as whole-rock incompatible trace element concentrations show a linear, negative correlation with the mass fraction of crystals in the sample. Simple crystal accumulation models, however, fail to explain the compositional variation, and one explanation is that the homogeneous Laki melt mixed with varying proportions of a crystal mush that contained its own liquid. The results of thermobarometry calculations indicate that the erupted Laki liquid was in equilibrium with olivine, plagioclase and augite at 1-3 kb. Most of the crystals carried by the flow are too primitive to have crystallised from the erupted liquid and barometry calculations indicate that clinopyroxene crystallised at 3-7 kb. The majority of the large crystals hosted in the Laki basalt samples are therefore antecrysts that grew within the same magma plumbing system as the Laki carrier melt but are not in direct chemical equilibrium with it. This finding is verified by the fact that olivine crystals that are too magnesian to be in chemical equilibrium with the Laki whole-rock composition contain melt inclusions with average La/Yb values that are the same within error as the whole-rock values. The wide range of La/Yb values in melt inclusions hosted in the most magnesian (Fo86) olivine crystals in comparison to the least magnesian (Fo<74) indicates the initial variability of the Laki magma prior to concurrent crystallisation and extensive mixing, which acted to homogenise the carrier melt composition. The preservation of a wide range of La/Yb within the melt inclusions in comparison to the whole-rock composition, and a range of La/Yb values in different inclusions from the same crystal, indicates short timescales between melt inclusion entrapment and quenching during eruption. Melt inclusion studies also reveal the dissolved volatile content of the Laki magma at the onset of olivine crystallisation, although the majority of H2O concentrations have almost certainly been reset by low pressure diffusive exchange with the host crystal or surrounding magma. Comparison of the behaviour of volatiles with that of incompatible elements in the melt inclusions indicates that CO2 was degassing during olivine crystallisation, but S, F and Cl were not. New estimates of total volatile loading to the atmosphere during the eruption based on melt inclusion volatile concentrations show SO2 and HCl loading comparable to previous estimates, but higher HF loading. Mass balance calculations show that the observed H2O and CO2 concentrations of melt inclusions hosted in olivines in chemical equilibrium with the Laki whole-rock composition are ~50% and ~93% lower respectively than would be expected if no pre-eruptive degassing of the magma reservoir had occurred, meaning that pre-eruptive degassing of H2O and CO2 from the magma must have been significant. Lava flows from Thjórsá are more compositionally variable than those from Laki, and have different average major and trace element compositions. Compositional variation within the Thjórsá whole-rock composition is explained by a combination of source variation and fractional crystallisation, and, unlike Laki, is not strongly controlled by crystal accumulation.

The effects of thermal discharges on the density, distribution, production, and drift of benthic organisms were studied at North Lake reservoir.

The Columbus Basin, offshore Trinidad, is a mature gas producing basin with a number of major fields now in decline. Focus for infield exploration and production is shifting, with thin bedded sandstones as a secondary pay target. This basin is exceptional as age equivalent analogues to the subsurface reservoirs are exposed along the south east coast of Trinidad at Mayaro Bay (16 – 25 m sections). This research utilizes these outcrops and integrates findings with subsurface core data to present an improved understanding of thin bedded sandstones in three significant areas: 1) depositional setting on a wave dominated delta through description and interpretation of their large scale architecture and facies associations, 2) reservoir quality and connectivity of the facies and microfacies that comprise these heterolithic units through petrography and pore system characterization and 3) pore scale reservoir quality and connectivity through micro CT imaging and 3D modelling of their pore system morphology. Detailed sedimentological analysis has revealed that thin beds are highly interbedded units with thicknesses of 0.1 – 10 cm and have a lenticular geometry. Their lateral extent, controlled by their exposure, varies from 3 to 10s m in some areas. Field sampling and microfacies analysis, revealed five distinct lithofacies types and five microfacies types that make up two principal facies associations (FA): (FA1) axial distal delta front facies and (FA2) lateral distal delta front facies. The reservoir quality poroperm data achieved for the thin sandstones of these two facies associations are consistent with routine core analysis data from basin core and industry assigned values for conventional thicker bedded sandstones, inferring their secondary reservoir potential. Utilizing new techniques such as X-Ray tomography, a high resolution 3D model of the thin sandstone pore systems has been created for qualitative and quantitative reservoir characterization, especially vertical and lateral connectivity within the thin bedded units. This detailed dataset of 3D pore dimensions that can be used as conditioning data for other reservoir models. The observations and conclusions of this research give an insight into the depositional architecture and thin bedded sandstones on a distal delta front and their associated reservoir properties and connectivity mechanisms that facilitate an effective reservoir. These findings may inform and guide future exploration and appraisal, development and production and well completion and configuration programmes for thin bedded reservoirs as explained by the implications and recommendations at the end of this thesis.

Master of Science / Department of Geology / Matthew W. Totten / The area of study for this project is the Leach Field, which is located in Jackson County, Kansas. Production in the Leach Field has historically been disappointing, with 388,787 barrels of oil being produced since the field’s discovery in 1963 (KGS, 2015). Production of the field has been highly variable, with only 20,568 barrels of oil being produced in the last 20 years. Economic and other concerns that have impacted production and production rates of the field include: low oil prices soon after its discovery, numerous changes of ownership, and lack of significant production infrastructure in the area. Stroke of Luck Energy & Exploration, LLC. has recently purchased the majority of the leases and wells in the Leach Field, and is reestablishing the field as a productive oil field. Plans include: washing down several plugged and abandoned wells, and drill new wells to increase production in the field. The goal of this study was to determine the major geologic factors controlling reservoir quality in the Hunton and Viola Limestone Formations in the Leach Field, so that a future exploration model can be developed to help increase and stabilize the field's overall production. This model was created by applying several testing methods including: well logging analysis, microscope analysis, and subsurface mapping. Based on these results it was determined that the quality of the reservoir rocks is controlled by the degree of dolomitizaiton in both formations. Reservoir quality is as important as structure in determining well productivity in the Leach Field.

Reservatórios de petróleo são ambientes únicos por apresentarem uma combinação de condições extremas referentes à temperatura, pressão e salinidade, e que sustentam o desenvolvimento de procariotos. Várias espécies dos Domínios Bactéria e Archaea têm sido isoladas deste ambiente, com destaque aos microrganismos redutores de sulfato (BRS), metanogênicos e fermentadores. Estes últimos utilizam como fonte de energia uma grande variedade de compostos orgânicos e uma grande parte de seus representantes em reservatórios pertence ao Filo Thermotogae. Estas bactérias apresentam uma estrutura característica envolvendo a célula, semelhante a uma bainha, chamada toga. Alguns gêneros deste Filo são habitantes exclusivos de reservatórios, como por exemplo, o gênero Petrotoga. O presente trabalho teve como objetivo isolar e caracterizar bactérias da classe Thermotogae a partir de fluidos de água/óleo de poços de um reservatório de petróleo localizado na região Nordeste, com vistas a contribuir para o conhecimento da diversidade e metabolismo microbianos deste tipo de ambiente. O reservatório tem salinidade média de 7%, temperatura média de 60ºC, o pH dos fluidos situa-se entre 6,6-6,8, e a profundidade média dos poços é de 1.100 metros. Dois meios propostos na literatura para o cultivo de Petrotoga foram testados para o isolamento deste gênero: meio P-mexicana e meio P. olearia. Os meios foram preparados em anaerobiose, sob atmosfera de N2 e salinidade de 70g/L de NaCl. Inóculos de cultivos pré-existentes em meios enriquecidos foram feitos nestes meios e incubados a 60ºC. Ambos os meios se mostraram seletivos para linhagens de Petrotoga. Os isolados foram identificados pelo sequenciamento do gene RNAr 16S, e um deles, o isolado MG414-03, foi submetido a testes de crescimento sob as variáveis temperatura, salinidade e fonte de carbono. MG414-03 pertence ao gênero Petrotoga, com similaridade de 99,2% com a espécie Petrotoga miotherma. Suas células têm forma de bastonete e são envolvidas por toga; são Gram-negativas; têm comprimento médio de 1,8&plusmn;0,9 &mu;m e largura média de 0,7&plusmn;0,1 &mu;m, podendo ser individuais ou formar filamentos. Motilidade foi observada em células individuais e em arranjos de dois. Endósporos não foram observados em nenhuma fase de crescimento. Forma colônias circulares lisas, com borda lisa, transparentes, com diâmetro máximo de 1,0 mm. O isolado apresentou temperatura e salinidade ótimas de 60ºC e 4%, respectivamente. Utiliza glicose, xilose, maltose e sacarose como fontes de carbono, mas não utiliza xilana e carboximetilcelulose (CMC). É inibido pelos antibióticos canamicina e cloranfenicol nas concentrações de 10 &mu;g/mL e 100 &mu;g/mL, respectivamente. As atividades enzimáticas sobre os substratos xilana e carboximetilcelulose (CMC) foram testadas para o isolado MG414-03 e para as linhagens Petrotoga mobilis-DSM10674 e Petrotoga mexicana-DSM14811. O método utilizado foi o ensaio colorimétrico com DNS (Ácido Dinitrossalicílico) e o isolado MG414-03 não apresentou atividade enzimática sobre os substratos testados. Petrotoga mobilis-DSM10674 e Petrotoga mexicana-DSM14811 foram utilizadas como padrões no ensaio pois ambas são descritas como produtoras de xilanases, fato confirmado pelos resultados apresentados no teste. Petrotoga mobilis-DSM10674 apresentou atividade enzimática sobre o CMC, na ordem de 73&plusmn;18 U/L, fato não registrado na literatura para esta espécie. / Oil reservoirs are unique environments for having a combination of extreme conditions relating to temperature, pressure, salinity, and that support the growth of microorganisms. Several species of Domains Bacteria and Archaea have been recovered from oil reservoirs, especially the sulfate-reducing microorganisms (SRB), methanogens and fermenters. The latter use as a carbon source a wide variety of organic compounds and a large fraction of the strains are members of the Phylum Thermotogae. Thermotogae species share a common characteristic: a balloon-like sheath or &ldquo;toga&rdquo; present outside the cell membrane. Some genera of the phylum have been exclusively recovered from oil reservoirs, as the genus Petrotoga. This study aimed to isolate and characterize strains members of Thermotogae from water/oil fluids of an onshore oil reservoir located in the Northeast of Brazil, in order to contributes to the knowledge of diversity and microbial metabolism of this type of environment. The reservoir has an average salinity of 7%, an average temperature of 60 º C, the pH of the fluid is between 6.6-6.8 and the average depth of the wells is 1,100 meters. Two culture media proposed in the literature for Petrotoga cultivation were tested: P-mexicana Medium and P. olearia medium. The media was prepared anaerobically under N2 flush and salinity adjusted for 70g/L NaCl. Aliquots from pre-existing enriched cultures were inoculated in those media and incubated at 60 º C. Both media proved be selective for Petrotoga strains. The isolates were identified by 16S rRNA gene sequencing, and the isolate MG414-03 was tested for the growth under variables temperature, salinity and carbon source. MG414-03 belongs to the genus Petrotoga, with 99.2% similarity with Petrotoga miotherma species. Cells are rods, 1.8 (&plusmn; 0.9) x 0.7 (&plusmn; 0.1) &mu;m in size, with an outer sheath-like structure (toga), occurring singly or in sheaths. It stains Gram-negative. Motility was observed in single or in double cells. No spore formation was detected. Colonies are circular, with a smooth edge, transparent, with a maximum diameter of 1.0 mm. Optimum salinity at 4% and optimum temperature at 60ºC. Ferments glucose, xylose, maltose and sucrose, but not xylan and carboxymethylcellulose (CMC). It is inhibited by the antibiotics kanamycin and chloramphenicol at concentrations of 10 &mu;g/mL and 100 &mu;g/mL, respectively. The enzymatic activity on xylan and carboxymethylcellulose (CMC) were tested for isolate MG414-03, Petrotoga mobilis DSM10674 and Petrotoga Mexicana DSM14811. The method used was the colorimetric assay with DNS (dinitrosalicylic acid) and isolate MG414-03 showed no enzymatic activity on the tested substrates. Petrotoga mobilis DSM10674 and Petrotoga Mexicana DSM14811 were used as standards in the DNS assay, as both strains are described as xylanase producers, and this ability was confirmed by the results presented in the test. Petrotoga mobilis-DSM10674 showed enzymatic activity on CMC, of 73 &plusmn; 18 U/L, which was not recorded in the literature for this species.

No Brasil, cerca de dois terços da capacidade total instalada de geração de energia elétrica e, em média nos últimos quinze anos, aproximadamente 90% da geração efetiva provêm das hidrelétricas. Este sistema inclui 170 usinas hidrelétricas de médio e grande porte existentes ou previstas até 2023, aproximadamente dois terços delas com capacidade de regularizar vazões e todas operando de maneira interligada. Restrições ambientais, técnicas, sociais e econômicas tem dificultado cada vez mais a implantação de empreendimentos hidráulicos contendo reservatórios de grande porte, tornando a maioria dos novos empreendimentos a fio d´água. Para compreender melhor o processo, este trabalho apresenta um levantamento da evolução anual da capacidade instalada e de armazenamento do sistema desde 1950 até a expansão prevista nos próximos 8 anos, em 2023. Os dados da década de 2000 e a previsão até 2023 de forma ainda mais acentuada indicam uma redução continua e significativa da capacidade relativa de regularização, com impacto direto nas decisões de operação e de expansão do sistema térmico complementar. A fim de avaliar as possíveis consequências da redução da capacidade de regularização, simulações foram realizadas no modelo HIDROTERM (ZAMBON et al. 2012); os resultados apontam para uma necessidade de ser complementar continuamente a energia hídrica, não só em períodos hidrologicamente desfavoráveis. / In Brazil, about two-thirds of electricity installed capacity and over the last fifteen years, on average 90% of energy consumed has come from hydropower generation. The hydro system includes 170 medium and large hydropower plants in integrated operation today or planned to be operational by the end of 2023, about two-thirds of them have large storage capacities to regulate flows. Environmental, technical, social and economic constraints have made it increasingly difficult to project and build new reservoirs with large storage capacities. As a result, newly built hydropower plants are mostly the run-of-river type. To better understand the process, this paper presents a historical survey of the installed capacity of hydropower and storage capacity of the system since 1950 and extends to the planned expansion over the next eight years, through 2023. Data from 2000 and projections through 2023 indicate a significant reduction of relative regulating capacity, which has a direct impact on decisions regarding operation and expansion of the complementary thermal system. In order to assess the possible consequences of the reduction in regulating capacity, simulations were performed on HIDROTERM model (ZAMBON et al. 2012); the simulation results point to a continuous need for complementing the hydropower generation, not only on hydrologically unfavorable years.

Reservoir sediment flushing is increasingly considered beneficial to reduce sedimentation of reservoirs and maintain sediment supply downstream of impounded rivers. Nevertheless, flushing of the accumulated sediments downstream of the dam also bears numerous negative impacts. In this study, first the most important downstream impacts of fine sediment releases of flushing were identified based on previously published research of twenty case studies in eleven countries. The results showed that the long-term as well as short term biological and physical impacts decreased with distance from the dam. The temporal scale of impacts on macro-invertebrates could span from few weeks or a month to several months while the effect on fish could last for a number of years. The impacts on downstream vegetation dynamics is driven by many years of flushing activities. The study also enabled proposing generic management strategies aimed to reduce the impacts. Second, fine sediment transport in coarse immobile bed, which is a common phenomenon downstream of dams during flushing releases, dam removal and also in many mountain and canyon rivers, was investigated. Particularly, the dynamics of the downstream erosion and transport of fine sediments released during sediment flushing was investigated based on a series of flume experiments that were carried out in immobile gravel bed and using a one-dimensional (1-D) suspended sediment transport model developed in the present study. In the framework of the flume experiment, firstly gravel bed roughness, porosity and roughness density were exclusively extracted from gravel surface elevation data in which developing a spatial filter to overcome elevation errors was carried out. Secondly a new technique to acquire fine sediment erosion in immobile coarse bed in running water condition was developed. The method proved to be the back bone of all fine sediment erosion experiments conducted in the present study and could be used for similar studies. This study presents a first work of direct measurement of erosion rate and characterizing its spatial heterogeneity in gravel bed. The experimental data of erosion rate of fine sediments showed that it varied spatially with high erosion rate on the stoss side of gravels and less on the lee side conforming to sweeps and ejections characteristics in coherent flow structure of gravel bed flows. Erosion rate was significantly affected by increase in roughness of immobile gravel bed with high erosion rate noticed when sand level was reduced although the effect on stream-wise velocity was not significant. The vertical profile of erosion rate was found to decrease linearly and showed an exponential decay in time in the gravel matrix. Third, a new non-equilibrium erosion rate relation is proposed. Drag force profile in the interfacial sublayer of clean gravel bed was found to be scaled well with roughness density and allowed predicting the effective shear stress distribution available for fine sediment entrainment with an empirical equation. vi The new relation is a modified version of the pick-up rate function of van Rijn (1984b) in which the predicted shear stress in the roughness layer was implemented. The most important finding was that if the shear stress distribution in the interfacial sublayer is predicted, a relation for sand bed condition can be applied to predict fine sediment erosion rate in immobile gravel bed. This approach is conceptually superior to previous approaches where erosion rate in sand bed condition was scaled empirically for various fine sediment bed level within the interfacial sublayer. Finally, the effect of the interaction between hydrodynamic and sediment wave dynamics of sediment flushing on spatial pattern of sediment deposition was investigated. The 1-D model was developed to include major processes observed in sediment flushing: sediment wave celerity correction, variable bed roughness, bed exchange in immobile bed, hindered settling velocity and rough bed porosity. The proposed erosion rate relation showed encouraging results when implemented in the 1-D model. The wave celerity factor did not show significant effect on the spatial lag in immobile bed condition although was significant in sand bed condition. Variable bed roughness modified both the flow field and sediment deposition in which larger length of sediment deposit was noted. The immobile bed porosity allowed modelling clogged depth of fine sediments. The model was also found to be very valuable to investigate flushing scenarios that reduce significant deposition through the analysis of the dependence of deposition on peak-to-base flow and intermittence of releases. The highest peak-to-base flows produced the longest and thickest region of deposition while those with the lowest ratio produced the shortest and thinnest. A single flushing release followed by clear water release reduced area or length of sediment deposition more than intermittent flushing followed by inter- and post-flushing clear water releases. In the latter case, the peak of concentration reduced but remained higher for longer duration than the former, which suggests that a large quantity of clear water release has to be available. Overall, the present research represents a step forward in understanding relevant processes involved in the downstream transport of fine sediments released during sediment flushing and the associated impacts that can help the development of better management strategies and predictive tools.