Luiz Fernando De Ros

Universidade Federal do Rio Grande do Sul | UFRGS · Institute of Geosciences

Sequence stratigraphy is a useful tool for the prediction of primary (depositional) porosity and permeability. However, these primary characteristics are modified to variable extents by diverse diagenetic processes. This chapter demonstrates that integration of sequence stratigraphy and diagenesis is possible because the parameters controlling the...

The genesis and evolution of lacustrine pre-salt carbonate reservoirs, which contain giant hydrocarbon accumulations along the South Atlantic margins, has attracted major research interest. The huge extension and volume, and unusual textural and compositional features, are key elements for understanding the tectonic, structural, stratigraphic, and...

The discovery of large oil accumulations in the rift and sag Pre-Salt sections of the Campos and Santos Basins has revived interest in the exploration of the lacustrine carbonate reservoirs in the Brazilian and African marginal basins. More than half of Brazilian oil production originates from the Pre-Salt reservoirs of these offshore basins. A stu...

The spatial and temporal distribution of diagenetic alterations in siliciclastic sequences is controlled by a complex array of interrelated parameters that prevail during eodiagenesis, mesodiagenesis and telodiagenesis. The spatial distribution of near-surface eogenetic alteration is controlled by depositional facies, climate, detrital composition...

The magmatic events and their related hydrothermal fluids played a fundamental role in the formation, diagenesis, and quality of the Aptian Pre-Salt reservoirs of Campos and Santos basins, offshore eastern Brazil. Hydrothermal vents have been recognized in seismic lines of these basins. On the other hand, the anomalous amount of CO2 in Pre-Salt res...

The Pangaea assemblage resulted in significant tectonic and eustatic changes, but also a well-known desertification triggered by the increasing continentalization. While the northern hemisphere basins have been thoroughly studied, several recent studies on southern hemisphere basins bring new insight on how these events affected the Gondwana hinter...

Since the discovery of giant Aptian pre-salt reservoirs in Brazilian margin basins, the study of lacustrine carbonates has drawn great attention from the scientific community. Comparatively, minor attention was given to the characterization and genesis of the Mg-silicates (e.g., stevensite, kerolite) which are commonly associated with these carbona...

Since the discovery of giant Aptian pre-salt reservoirs in Brazilian margin basins, the study of lacustrine carbonates has drawn great attention from the scientific community. Comparatively, minor attention was given to the characterization and genesis of the Mg-silicates (e.g., stevensite, kerolite) which are commonly associated with these carbona...

Aptian siliciclastic onshore deposits of the Mucuri Member are important reservoirs in the Espírito Santo Basin (eastern Brazil). A detailed quantitative petrographic and textural analysis of well core samples was performed in order to unravel their depositional processes and conditions, in relation to previously proposed depositional models. The r...

The Late Cambrian Steptoean Positive Carbon Isotope Excursion marks a time of significant change in ocean chemistry and trilobite faunas. On the lead up to the SPICE and at the SPICE itself, there is global evidence from Laurentia and Gondwana of cementation by primary aragonite in shallow subtidal environments accompanied by deposition of aragonit...

The objective of this presentation is to explore the syngenetic, diagenetic and hydrothermal processes responsible for the formation and evolution of the Pre-salt sag section of Santos and Campos basins, discussing their role on the quality of the reservoirs, as well as their probable genetic conditions, in the context of the extraordinary early hi...

Shallow marine carbonates constitute some of the most productive oil reservoirs of the world. In Brazil, offshore oil production began from Albian, post-salt marine carbonate reservoirs of the Campos Basin, which lost their importance with the increasing discoveries and production from Upper Cretaceous and Paleogene clastic turbidites and, more rec...

Aptian lacustrine pre-salt carbonate reservoirs contain giant hydrocarbon accumulations along the South Atlantic margins. Systematic petrographic and geochemical studies are essential to unravel the origin and evolution of these unusual reservoirs and associated rocks. Aptian Pre-salt deposits are essentially composed of syngenetic, chemically prec...

The Itaboraí Basin, located in Rio de Janeiro state, is the smallest segment of the Southeastern Brazil Continental Rift, and the first to open, during Palaeocene. Numerous studies focused on its fossiliferous content, but few systematically approached its depositional and diagenetic processes and products. A detailed description of the basal sedim...

This study aims to provide a better understanding of the genesis and diagenetic evolution of the rift pre-salt deposits of the Santos Basin, in the context of evolution of the lake system in which the sediments were deposited. The study of the syngenetic and early diagenetic constituents and their paragenetic relations allowed reconstruction of the...

The forearc succession of Great Valley Group in Central California provides some of the best examples of giant sand injection complexes in the world and is therefore considered valuable analogues for injectite systems in the subsurface. Several sand injection complexes are well described in the outcrop and subsurface, however the petrographic chara...

The Espírito Santo Basin, one of the Brazilian marginal basins formed during the Gondwana break-up, is composed by three main depositional units – rift, sag and drift phases. The Mucuri Member sandstones are the Aptian sag phase related, onshore reservoirs deposited at the margins of the lacustrine system were the pre-salt (pre-evaporitic successio...

Petrographic, mineralogical, elemental, isotopic and fluid inclusion analyses were integrated to unravel the diagenetic evolution of Brazilian Pre-Salt lacustrine carbonate reservoirs of northern Campos Basin, southeast Brazilian margin. Detailed thin section and cathodoluminescence petrography, scanning electron microscopy and electron microprobe...

Quantitative petrography and stable-isotope and fluid-inclusion analysis revealed that the diagenetic evolution of two Tertiary turbidite sandstone reservoirs from the offshore part of the Espírito Santo Basin, eastern Brazil, was influenced by the flow of meteoric water and salt-dome-related fluids, which had different impacts on their quality. In...

Simulations of the observed patterns and paragenetic relations between calcite aggregates and Mg-clays in Presalt reservoirs from deposition to early evolution through a geochemical water-rock interaction simulator.

A evolução diagenética de dois reservatórios turbidíticos terciários da porção offshore da Bacia do Espírito Santo, foi influenciada tanto por processos meteóricos como por processos relacionados a domos salinos adjacentes aos reservatórios, que tiveram diferente impacto sobre sua qualidade. A precipitação de pirita framboidal, dolomita microcrista...

In many basins, Upper Cambrian carbonate successions display intervals with a positive carbon isotope excursion (CIE) of up to +5‰. In North America, this marks the boundary between the Sauk II–III super-sequences. A Steptoean positive carbon isotope excursion (SPICE) locality previously identified in the Port au Port peninsula, western Newfoundlan...

Technology is a strong ally for the acquisition of geological data. With the huge demand for fast and reliable results, changes and updates in the tools used by geologists are necessary. Investing in the generation of relevant data for aiding the interpretation and decision making during the exploration for oil reservoirs is critical for reducing t...

Cementation by quartz overgrowths and subsequently by carbonates is a very common global phenomenon in many sandstone basins that is poorly constrained in the literature. Integrated petrographic, stable isotope, fluid-inclusion microthermometry and Raman spectroscopy have helped unravel the diagenetic conditions, fluid flow and hydrocarbon migratio...

Litharenites composed of sedimentary and low-grade metamorphic rock fragments are rarely good hydrocarbon reservoirs. Most of their primary porosity is lost by ductile grain deformation during mechanical compaction. However, the lithic Carmópolis Member of the Muribeca Formation from the Sergipe-Alagoas Basin, NE Brazil, is one of the most importan...

This study has utilized carbon and oxygen isotopic data to unravel the origin of Holocene beachrock cements of Rio Grande do Norte State coast, northeastern Brazil. The cements are exclusively constituted of Mg-calcite, with isopachous prismatic rim, equant spar, cryptocrystalline coating or pore-filling, pseudo-peloidal, radial and scalenohedral h...

In the domain of E&P petroleum chain, the authors have developed a study and proposed a conceptual framework for inserting direct rock data into reservoir models, through calibration of well logs. This type of data is often ignored or manual processed in actual petroleum reservoir modeling activities, due to its high cost of acquisition, or due to...

A Bacia de Itaboraí é considerada o primeiro segmento do Rifte Continental do Sudeste do Brasil a se abrir, durante o Paleoceno. Há referências à existência de calcretes na bacia, entretanto, até o momento, não foram realizados estudos específicos sobre os calcretes e sobre sua ocorrência, e ainda há um número reduzido de trabalhos envolvendo a car...

Pedogenetic calcretes from the Itaboraí Basin, Rio de Janeiro State, Brasil. The Itaboraí Basin, located in Rio de Janeiro State, Brazil, is considered the first segment from the Sou­theastern Brazil Continental Rift opened, during the Paleocene. The occurrence of calcretes was previously reported in the literature, although studies dealing specifi...

Giant sand Injection complexes besides being special and intriguing geological phenomena play a very important role in the evolution of sedimentary basins and as hydrocarbon-bearing sandstone intrusion reservoirs. They are typified by evidence of sand fluidization and injection in the shallow crust and are recognized extensively in outcrops and in...

An integrated petrologic-sedimentologic-stratigraphic-seismic study of the Lagoa Feia Group, rift section of the Campos Basin, has shown that rift sedimentation was dominantly intrabasinal (carbonate and stevensitic deposits), with siliciclastic deposits restricted to the proximity of graben border faults. The bivalve bioclastic rudstones (" coquin...

Cementation by quartz overgrowths and subsequently by carbonates is a very common global paragenetic phenomenon in sandstones of many basins that is poorly constrained in the literature. Integrated petrography, electron microprobe, stable isotopes, fluid inclusion microthermometry, and Raman spectroscopy have helped unravel the diagenetic condition...

Slides of paper presentation

ABSTRACT: Quantitative petrographic analysis was conducted in vertical profiles of 8 turbidite beds of the Eocene-Oligocene Peïra Cava deep-marine mini basin in SE France in order to detect spatial trends in mineralogy related to the hydrodynamic sorting of particles. The analysis was mainly focused on sheet-like confined beds which can be traced t...

RESUMO: Um estudo baseado em microscopia ótica e eletrônica foi executado sobre os reservatórios da Formação Coqueiros e da Formação Macabu do Norte da Bacia de Campos com objetivo de avaliar a evolução diagenética e seu impacto sobre a qualidade dos reservatórios. Os principais constituintes primários dos reservatórios carbonáticos da Formação Coq...

Um método para detecção automática de tipos litológicos e contatos foi desenvolvido através da combinação de análises estatísticas de um conjunto de perfis geofísicos de poço convencionais, calibradas por descrições sistemáticas de testemunhos. O intuito desse projeto é permitir a integração de dados de rocha em modelos de reservatório. Os testemun...

Sequential descriptions or logs of outcrops and borehole cores provide key information for understanding the processes of generation and evolution of the rocks and their resources, such as accumulations of ores or petroleum. Currently, most sequential descriptions are still created using non-standardized data formats, in which geologists use free t...

A modelagem e simulação de processos diagenéticos requerem o entendimento dos processos químicos, físicos e biológicos atuantes em sedimentos a partir de sua deposição, durante e após a sua litificação e antes de seu metamorfismo. Para isto, diversos parâmetros devem ser especificados, incluindo a composição da água e dos minerais, e as condições d...

A new petrographical study was performed on the rift section of the Lagoa Feia Group, Lower Cretaceous of the Campos Basin, eastern Brazilian margin. The primary constituents of the analysed rocks are siliciclastic and volcaniclastic grains, stevensite ooids and peloids, and bioclasts of bivalves and ostracods. This study focused on the clastic, st...

Recent advances in seismic inversion have made it possible to integrate geophysical Elasto-Facies Associations (EFAs) into a more sophisticated workflow that allows for improved reservoir characterization. However, performing inversion still requires well data for the calibration of low frequency input models. Innovative solutions are therefore req...

Resumo. A cadeia de petróleo consiste em uma sequência de tarefas que inicia com a exploração de áreas potencialmente econômicas por geólogos e geofísicos, produzindo dados que são utilizadas para subsidiar as decisões dos engenheiros de petróleo sobre colocar ou não um determinado reservatório em produção. Cada um desses profissionais possui difer...

Despite a great interest in Brazilian Equatorial Margin exploration, very little was published on the diagenesis of sandstones from that area. A wide recognition petrographic study was performed to identify the major diagenetic processes that impacted the porosity of Lower Cretaceous sandstones of the Pará-Maranhão, São Luís, Bragança-Viseu and Bar...

Ontologies have been growing in importance regarding their reusability for distinct applications, since this allows amortizing the significant cost of development of a knowledge base. Large portions of knowledge models now are modelled as ontologies and these portions are shared through several applications. Considering the immature stage of the me...

Diagenetic reactions, characterized by the dissolution and precipitation of minerals at low temperatures, control the quality of sedimentary rocks as hydrocarbon reservoirs. Geochemical modeling, a tool used to understand diagenetic processes, is performed through computer codes based on thermodynamic and kinetic parameters. In a comparative study,...

The frequency distribution of turbidite bed thicknesses potentially contains information about the flow hydrodynamics, the processes by which flows are initiated and the character of their sources. Three main statistical models have been proposed to describe turbidite bed thickness distributions: a lognormal distribution model, a (segmented) power...

This study aims to evaluate the role of bed thickness and grain-size distributions in characterizing deep-marine turbidite systems. The purpose is to develop a methodology, based on a statistical approach, which can be used to evaluate the depositional sub-environment of turbidite deposits or to point out basin-wide differences between depositional...

Abundant early diagenetic siderites occur as spherulites and rhombohedral microcrystalline and macrocrystalline crystals in the cores of the 2-MU-1-RJ well, drilled in the Paraíba do Sul Deltaic Complex, Rio de Janeiro, eastern Brazil. The host sediments of the siderites are siliciclastic, hybrid and carbonate deposits. Intense pedogenetic processe...

Fluvial and estuarine sandstones of the Aptian Mucuri Member of the Mariricu Formation are the main reservoir rocks in the onshore portion of the Espírito Santo Basin, Brazilian eastern margin. These sandstones are contemporaneous with the major lacustrine pre-salt reservoir rocks which are currently the target of exploration offshore. The sandston...

An integrated petrologic-stratigraphic study was performed on the Sergi Formation, main reservoir of Recôncavo rift basin, north-eastern Brazil. Three third-order stratigraphic sequences, limited by regional unconformities, were defined: the basal Sequence I, characterized by intercalation of lacustrine and floodplain mudrocks with fluvial and aeol...

Upper Cretaceous sandstones are the main clastic reservoirs of the Santos Basin, eastern Brazil, showing high porosity at depths greater than 4000 m. Porosity preservation in these deep sandstones is ascribed to the inhibition of quartz cementation and pressure dissolution by authigenic porelining chlorite. Santos sandstones are mostly fine-grained...

Nesse artigo, é apresentada uma abordagem para caracterização e desenvolvimento de reservatórios baseada na análise de heterogeneidades deposicionais, suas hierarquias e como essas heterogeneidades devem ser focadas em um modelo de unidade de fluxo. O termo unidade de fluxo genética como utilizado nesse artigo representa um elemento que tem uma esc...

It is presented an approach for reservoir characterization and development based on the analysis of depositional reservoir heterogeneities, their hierarchy, and how these heterogeneities should be addressed in a flow unit model. Genetic flow units, as used in this paper, are scale-dependent elements that correspond to sub-systems of deposition (ass...

The Parecis Basin is a large intracratonic rift located in central Brazil and filled with Paleozoic carbonate, evaporite and siliciclastic sediments. The occurrence of gas seeps has recently attracted significant exploration interest by the Brazilian petroleum agency and by Petrobras. The continuously cored PB-01-RO well provided the first opportun...

A study of the rift to early drift phase, fluvial, deltaic and shallow-marine Lower Cretaceous (Upper Aptian to Lower Albian) siliciclastic sandstones, hybrid arenites and calcarenites from the Jequitinhonha Basin, eastern Brazilian margin, has shown that the distribution of diagenetic alterations and of related reservoir quality evolution can be c...

The challenge of exchanging data among the several activities that support the petroleum exploration and production is leading the modelers to investigate better practices in conceptual modelling. Ontology theory provides an adequate framework for making explicit the intended meaning of the geological concepts that support the applications. We desc...

Crescimentos autigênicos precoces de K-feldspato são abundantes nos arenitos fluviais cretácicos da Formação Açu (Bacia Potiguar), um dos mais importantes reservatórios onshore de hidrocarbonetos do Brasil. Estes crescimentos foram formados diretamente ao redor de K-feldspatos detríticos, em condições superficiais (eodiagênese inicial). A continuid...

Diagenesis exerts a strong control on the quality and heterogeneity of most clastic reservoirs. Variations in the distribution of diagenetic alterations usually accentuate the variations in depositional porosity and permeability. Linking the types and distribution of diagenetic processes to the depositional facies and sequence-stratigraphic framewo...

Early-authigenic K-feldspar overgrowths are widespread in the Cretaceous fluvial Açu Formation sandstones from the Potiguar Basin, one of the most important onshore oil reservoirs of Brazil. These overgrowths were formed at near-surface conditions (early eodiagenesis), directly on detrital K- feldspar grains. The physical continuity between overgro...

The provenance of the Maastrichtian deep-water reservoir sandstones from the Jubarte oil field (Campos Basin, eastern Brazil), was studied using an integrated approach that included quantitative petrography, conventional heavy mineral analysis, garnet mineral chemistry and zircon geochronology. The reservoirs are predominantly coarse, poorly-sorted...