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The Punta Negra Formation (FPN) constitutes a Lower-Middle Devonian sandstone unit located in the Argentine Precordillera. Based on detailed facies and ichnological analyses, this unit, which had been previously interpreted as a deep-water system, has been reinterpreted in this study as a prodelta system, in which the distribution and sedimentation of the clastic deposits were controlled by hyperpycnal flows associated with storms. Five lithofacies attest the deposition by unidirectional hyperpycnal flows combined with storm-generated oscillatory flows. Fossil traces testify variable energetic conditions of the depositional system with the colonization of opportunistic organisms immediately after the deposition of high energy combined flows and the colonization of more specialized organisms during the long low-energy periods. Three architectural elements, deposited from coastline to offshore, have been recognized: 1) Channelized sandstone, composed of the thickest and coarsest sandstone beds and interpreted as the proximal portion deposited close to the mouth of the distributaries of the delta system; 2) Tabular sandstone, which are composed of combined and oscillatory flow deposits with lesser thickness, grain size and spacing of the undulated bed forms; 3) Tabular sandstone interbedded to mudstone, which represents the most distal architectural element and is composed of thin sandstone and thicker mudstone strata, deposited by low-energy combined flows.

Pao de Acuar is certainly one of the most impressive and challenging hydrocarbon accumulations found in the prolific Campos Basin, offshore Brazil. This discovery opened a new frontier for exploration in Brazil’s ultradeep waters, in depths ranging from 2500 to 2900 m (8202 to 9514 ft). Pao de Acuar is the third discovery made by a consortium integrated by Repsol Sinopec Brasil (operator), Statoil do Brasil, and Petrobras in the Concession BM-C-33, with estimated resources of 700 million bbl of light oil and 3 tcf of gas. This discovery is the result of the integrated work of a multidisciplinary international team using some of the most advanced technologies available today in the oil exploration industry in seismic imaging, drilling, formation evaluation, and fluid-rock sampling analysis. This discovery consists of a significant hydrocarbon column hosted within a unique reservoir made up of a variety of basic volcanic rocks overlain by pervasively silicified microbial carbonate platform/ramps, grading toward profundal lake facies. This chapter summarizes the main results of the exploration and ongoing appraisal work regarding this unique hydrocarbon accumulation, highlighting both the complexity of the discovered reservoirs and the operational and technical challenges faced, and still to overcome, before beginning production.

Open-coast tidal flats are hybrid depositional systems resulting from the interaction of waves and tides. Modern examples have been recognized, but few cases have been described in ancient rock successions. An example of an ancient open-coast tidal flat, the depositional architecture of the Lagarto and Palmares formations (Cambrian–Ordovician of the Sergipano Belt, north-eastern Brazil) is presented here. Detailed field analyses of outcrops allowed the development of a conceptual architectural model for a coastal depositional environment that is substantially different from classical wave-dominated or tide-dominated coastal models. This architectural model is dominated by storm wave, low orbital velocity wave and tidal current beds, which vary in their characteristics and distribution. In a landward direction, the storm deposits decrease in abundance, dimension (thickness and spacing) and grain size, and vary from accretionary through scour and drape to anisotropic hummocky cross-stratification beds. Low orbital wave deposits are more common in the medium and upper portion of the tidal flat. Tidal deposits, which are characterized by mudstone interbedded with sandstone strata, are dominant in the landward portion of the tidal flat. Hummocky cross-stratification beds in the rock record are believed, in general, to represent storm deposits in palaeoenvironments below the fair-weather wave base. However, in this model of an open-coast tidal flat, hummocky cross-stratification beds were found in very shallow waters above the fair-weather wave base. Indeed, this depositional environment was characterized by: (i) fair-weather waves and tides that lacked sufficient energy to rework the storm deposits; (ii) an absence of biological communities that could disrupt the storm deposits; and (iii) high aggradation rates linked to an active foreland basin, which contributed definitively to the rapid burial and preservation of these hummocky cross-stratification deposits.

There is a shortage of petrophysical studies in microbialite facies and more importantly, the absence of these studies has created confusion over how industry and researchers should approach sampling these kinds of reservoirs. This work sought to define petrophysical properties in a Lagoa Salgada (Holocene) and Codo formation (Aptian) stromatolite by way of investigating petrophysical properties from each growth structure. Primary computations presented in this paper include porosity and permeability on sub samples imaged at multiple scales with a micro computed tomography (CT) scanner to attain the adequate Representative Elemental Volume (REV). Computations of porosity and permeability were performed at the pore scale and upscaled to the growth structures and finally to the whole stromatolite. Calculation of porosity and permeability trends revealed that sub sampling growth structures is not the most efficient way to investigate petrophysical properties, but a refined approach would precisely target different segmented CT phases. It also revealed how important REV and location are when extracting MICP samples in highly heterogeneous reservoirs.

Orientador: Giorgio Basilici Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica e Instituto de Geociencias Resumo: Áreas costeiras de planície de maré. cujos processos deposicionais são influenciados por ondas, são pouco conhecidas em sistemas deposicionais atuais e antigos. A Formação Lagarto representa um destes sistemas deposicionais misto com influência da atividade de maré e ondas. Este trabalho descreve os sedimentos que se desenvolvem neste sistema, interpreta os processos deposicionais e define um modelo de distribuição de sedimentos para esta formação. A Formação Lagarto pertence ao Domínio Estância, Faixa Sergipana e aflora nos estados da Bahia e Sergipe. Reconheceram-se seis litofácies sedimentares compostas de arenitos e lamitos, que formam três elementos arquiteturais: Depósitos de intermaré inferior, Depósitos de intermaré intermediário e Depósitos de intermaré superior. Os elementos arquiteturais são gerados pela inter-relação entre processos deposicionais de maré e oscilatórios (ondas de tempo bom e tempestade). Foram reconhecidos dois processos principais de distribuição horizontal dos sedimentos. No primeiro, os sedimentos são transportados pela ação de fluxos unidirecionais decorrentes das correntes de maré (fluxos de enchente e de vazante de maré). No segundo processo, os sedimentos são erodidos e transportados da porção mais distai para a mais proximal por fluxos oscilatórios ou combinados derivados de tempestade. De uma forma geral, há uma diminuição da granulação (formada, predominantemente, por areia fina e média fina na região de intermaré inferior e por lamito e areia muito fina na região de intermaré superior) e da espessura das camadas areníticas em direção à costa. Atribuiu-se para a Formação Lagarto um sistema de deposição transicional, desenvolvido em planície de maré aberta (Open Coast Tidal Fiat) Abstract: Coastal areas of wave-influenced tidal plains are not well known in recent and ancient depositional systems. The Lagarto Formation represents one of these mixed depositional systems influenced both by tide and wave activities. This work describes the sediments in this system, interprets the depositional processes and defines a distributional model of sediments to the Lagarto Formation. The Lagarto Formation belongs to the Estancia Domain, Sergipano Belt, outcropping in Bahia and Sergipe states. It has been recognized six lithofacies, which composes three architectural elements: Upper intertidal deposits. Intermediary intertidal deposits e Lower intertidal deposits. The architectural elements are generated by the inter- relation between tide and oscillatory processes (fair-weather and storm waves). It has been recognized two main processes of horizontal distribution of sediments. In the first case, the sediments are transported by unidirectional flows derived from tide currents (ebb and flood flows). In the second case, the sediments are eroded and transported from the distal to the proximal portion by oscillatory or combined flows developed from storms episodes. There are a fining (from fine and medium-fine sand in the lower intertidal to mud and very fine sand in the upper intertidal area) and thinning of the sandy beds landward. It has been attributed a transitional depositional system to the Lagarto Formation, developed in an Open Coast Tidal Flat Mestrado Reservatórios e Gestão Mestre em Ciências e Engenharia de Petróleo