Estruturas tectônicas cenozóicas na porção leste da Bacia Potiguar - RN

This thesis encompasses the integration of geological, geophysical, and seismological data in the east part of the Potiguar basin, northeastern Brazil. The northeastern region is located in South American passive margin, which exhibits important areas that present neotectonic activity. The definition of the chronology of events, geometry of structures generated by these events, and definition of which structures have been reactivated is a necessary task in the region. The aims of this thesis are the following: (1) to identify the geometry and kinematics of neotectonic faults in the east part of the Potiguar basin; (2) to date the tectonic events related to these structures and related them to paleoseismicity in the region; (3) to present evolutional models that could explain evolution of Neogene structures; (4) and to investigate the origin of the reactivation process, mainly the type of related structure associated with faulting. The main type of data used comprised structural field data, well and resistivity data, remote sensing imagery, chronology of sediments, morphotectonic analysis, x-ray analysis, seismological and aeromagnetic data. Paleostress analysis indicates that at least two tectonic stress fields occurred in the study area: NSoriented compression and EW-oriented extension from the late Campanian to the early Miocene and EW-oriented compression and NS-oriented extension from the early Miocene to the Holocene. These stress fields reactivated NE-SW- and NW-SE-trending faults. Both set of faults exhibit right-lateral strike-slip kinematics, associated with a minor normal component. It was possible to determine the en echelon geometry of the Samambaia fault, which is ~63 km long, 13 km deep, presents NE-SW trend and strong dip to NW. Sedimentfilled faults in granite rocks yielded Optically Stimulated Luminescence (OSL) and Single-Aliquot Regeneration (SAR) ages at 8.000 - 9.000, 11.000 - 15.000, 16.000 - 24.000, 37.000 - 45.500, 53.609 - 67.959 e 83.000 - 84.000 yr BP. The analysis of the ductile fabric in the João Câmara area indicate that the regional foliation is NE-SW-oriented (032o - 042o), which coincides with the orientation of the epicenters and Si-rich veins. The collective evidence points to reactivation of preexisting structures. Paleoseismological data suggest paleoseismic activity much higher than the one indicated by the short historical and instrumental record

Caracterização tectono-estratigráfica da sequência transicional na sub-bacia de Sergipe

This thesis deals with the tectonic-stratigraphic evolution of the Transitional Sequence in the Sergipe Sub-basin (the southern segment of the Sergipe-Alagoas Basin, Northeast Brazil), deposited in the time interval of the upper Alagoas/Aptian stage. Sequence boundaries and higher order internal sequences were identified, as well as the structures that affect or control its deposition. This integrated approach aimed to characterize the geodynamic setting and processes active during deposition of the Transitional Sequence, and its relations with the evolutionary tectonic stages recognized in the East Brazilian Margin basins. This subject addresses more general questions discussed in the literature, regarding the evolution from the Rift to the Drift stages, the expression and significance of the breakup unconformity, the relationships between sedimentation and tectonics at extensional settings, as well as the control on subsidence processes during this time interval. The tectonic-stratigraphic analysis of the Transitional Sequence was based on seismic sections and well logs, distributed along the Sergipe Sub-basin (SBSE). Geoseismic sections and seismic facies analysis, stratigraphic profiles and sections, were compiled through the main structural blocks of this sub-basin. These products support the depositional and tectonic-stratigraphic evolutionary models built for this sequence. The structural analysis highlighted similarities in deformation styles and kinematics during deposition of the Rift and Transitional sequences, pointing to continuing lithospheric extensional processes along a NW trend (X strain axis) until the end of deposition of the latter sequence was finished by the end of late Aptian. The late stage of extension/rifting was marked by (i) continuous (or as pulses) fault activity along the basin, controling subsidence and creation of depositional space, thereby characterizing upper crustal thinning and (ii) sagstyle deposition of the Transitional Sequence at a larger scale, reflecting the ductile stretching and thinnning of lower and sub crustal layers combined with an increasing importance of the thermal subsidence regime. Besides the late increments of rift tectonics, the Transitional Sequence is also affected by reactivation of the border faults of SBSE, during and after deposition of the Riachuelo Formation (lower section of the Transgressive Marine Sequence, of Albian age). It is possible that this reactivation reflects (through stress propagation along the newlycreated continental margin) the rifting processes still active further north, between the Alagoas Sub-basin and the Pernambuco-Paraíba Basin. The evaporitic beds of the Transitional Sequence contributed to the development of post-rift structures related to halokinesis and the continental margin collapse, affecting strata of the overlying marine sequences during the Middle Albian to the Maastrichtian, or even the Paleogene time interval. The stratigraphic analysis evidenced 5 depositional sequences of higher order, whose vertical succession indicates an upward increase of the base level, marked by deposition of continental siliciclastic systems overlain by lagunar-evaporitic and restricted marine systems, indicating that the Transitional Sequence was deposited during relative increase of the eustatic sea level. At a 2nd order cycle, the Transitional Sequence may represent the initial deposition of a Transgressive Systems Tract, whose passage to a Marine Transgressive Sequence would also be marked by the drowning of the depositional systems. At a 3rd order cycle, the sequence boundary corresponds to a local unconformity that laterally grades to a widespread correlative conformity. This boundary surface corresponds to a breakup unconformity , being equivalent to the Pre-Albian Unconformity at the SBSE and contrasting with the outstanding Pre-upper Alagoas Unconformity at the base of the Transitional Sequence; the latter is alternatively referred, in the literature, as the breakup unconformity. This Thesis supports the Pre-Albian Unconformity as marker of a major change in the (Rift-Drift) depositional and tectonic setting at SBSE, with equivalent but also diachronous boundary surfaces in other basins of the Atlantic margin. The Pre-upper Alagoas Unconformity developed due to astenosphere uplift (heating under high lithospheric extension rates) and post-dates the last major fault pulse and subsequent extensive block erosion. Later on, the number and net slip of active faults significantly decrease. At deep to ultra deep water basin segments, seaward-dipping reflectors (SDRs) are unconformably overlain by the seismic horizons correlated to the Transitional Sequence. The SDRs volcanic rocks overly (at least in part) continental crust and are tentatively ascribed to melting by adiabatic decompression of the rising astenospheric mantle. Even though being a major feature of SBSE (and possibly of other basins), the Pre-upper Alagoas Unconformity do not correspond to the end of lithospheric extension processes and beginning of seafloor spreading, as shown by the crustal-scale extensional structures that post-date the Transitional Sequence. Based on this whole context, deposition of the Transitional Sequence is better placed at a late interval of the Rift Stage, with the advance of an epicontinental sea over a crustal segment still undergoing extension. Along this segment, sedimentation was controled by a combination of thermal and mechanical subsidence. In continuation, the creation of oceanic lithosphere led to a decline in the mechanical subsidence component, extension was transferred to the mesoceanic ridge and the newly-formed continental margin (and the corresponding Marine Sequence) began to be controlled exclusively by the thermal subsidence component. Classical concepts, multidisciplinary data and new architectural and evolutionary crustal models can be reconciled and better understood under these lines

Reavaliação de critérios estruturais na hidrogeologia de terrenos cristalinos, com ênfase na neotectônica e sensoriamento remoto

Hydrogeological prospecting in Northeast Brazil and in other crystalline terrains has been developed on the basis of structural and regional geology concepts that date back to the 50-60 decades and, as such, demand a natural re-evaluation and update. In this kind of terrain, the percolation and accumulation of ground water are controlled by fractures and other types of discontinuities, such as foliations and geological contacts that, through weathering, impart porosity and permeability to the rocks, allowing water flow and storage. Several factors should be considered in the process of locating water wells, as discussed in the literature. Among these, the kind of structures, fracture geometry (including aperture and connectivity) and their geological and chronological context. It is important to correlate fracture systems with the regional neotectonic framework. Fractures at low angle (sub parallel) with the principal stress axis (s1) are those which tend to open (actually they work as tension joints) and, in principle, would present major hydric potential; in the opposite side, fractures at high angle to s1 would behave as closed by a compressional component. Fractures diagonal to the compression and tension axes correspond to shear fractures and, due to their connectivity with second fractures, are also important in terms of hydric potential. Uplift followed by terrain denudation leads to decompression and a general tendency to open (aided by weathering processes) fractures and other rock discontinuities, at different orientations. Low angle fractures, formed in this context, are equally important to increase connectivity, collection of water and recharge of the aquifer systems. In a general way, an opening component (neotectonic or by terrain decompression) and several models to increase fracture connectivity correlate with a greater hydric potential of these structures. Together with parallel research, this thesis addresses models of ground water occurrence in crystalline terrains, either improving well established concepts like the (Riacho-Fenda model), but also stressing other possibilities, like the role of alluvium and paleo-regoliths (the Calha Elúvio-Aluvionar model) and of strongly altered, permo-porous zones placed at variable depths below the present surface, flanking several types of discontinuities, especially interconnected fracture arrays (the Bolsões de Intemperismo model). Different methodological approaches are also discussed in order to improve success rates in the location of water wells in crystalline terrains. In this methodological review, a number of case studies were selected in the eastern domain of the State of Rio Grande do Norte, involving the localities of Santa Cruz, Santo Antônio, Serrinha, Nova Cruz, Montanhas, Lagoa de Pedras and Lagoa Salgada. Besides the neotectonic analysis of brittle structures, this Thesis addresses the validation of remote sensing as a tool for ground water prospecting. Several techniques were tested in order to detect and select areas with higher potential for ground water accumulation, using Landsat 5-TM and RADARSAT images, besides conventional aerial photos. A number of filters were tested to emphasize lineaments in the images, improving their discrimination, to identify areas with higher overburden humidity, which could reflect subsurface water accumulation, as well as alluvium and other sedimentary covers that might act as recharge zones. The work started with a regional analysis with the orbital images, followed by analysis of aerial photos, up to a detailed structural study of rock exposures in the terrain. This last step involved the analysis of outcrops surrounding wells (in a ray of approximately 10 to 100 m) with distinct productivities, including dry examples. At the level required for detail, it was not possible to accomplish a statistical approach using the available well data catalogs, which lack the desired specific information. The methodology worked out in this Thesis must undergo a testing phase through location of new water wells. An increase in the success rates as desired will led to a further consolidation step with wider divulgation of the methodology to private companies and governmental agencies involved in ground water prospecting in crystalline terrains

Dinâmica Costeira dos Campos petrolíferos Macau/Serra, litoral setentrional do Estado do Rio Grande do Norte

This thesis describes the general behavior of the northern shore of the State of Rio Grande do Norte relating beach profile morphology with hydrodynamic and sedimentological parameters. The Macau and Serra Oil Field are inserted on this area and are under accelerated coastal erosion. At these oil fields are installed oil wells from PETROBRAS, nowadays located directly in the shoreline, under constant attacks of coastal processes (e.g. waves, tides and currents), which promote an intense morphodynamic variability of this sandy coast. The area was monitored for 24 months in three different stations (P01, P02 and P03). The methodology applied involved current techniques of beach profiles, hydrodynamical processes, remote sensing and geophysics. A synthesis of results obtained through the use of different time scales (monthly, lunar cycle, seasonal, annual) from a coastal dynamics study is presented. The average wind direction corresponded to 77ºAz (NE). The steepness of the berm and of the shoreface, as well as coastal current direction, do not present major changes, with an average of 36º for the steepness of the berm, 15º for the shoreface and 15º for the coastal current direction. This data set allows us to infer that the months of larger coastal erosion were November/2000 and April/2001, because of the largest wave parameter during this time. The months of worse coastal erosion in this area are related with the increasing wavy energy. This in turn, seems to be related to seasonal climatic variations, with the wave energy and tide currents speed increasing during months of minor precipitations (June to January). The months of worse coastal erosion were September and November, when the largest wave parameters and speed currents are measured in the area. Since these months are included on the period of minor precipitations, we related the coastal erosion to seasonal climatic variations. The results obtained during these 24 months of monitoring confirms a situation of accentuated erosion, mainly in Profile 03 (Barra do Corta-Cachorro), where the wave height, period, and coastal current speed are always larger than the values found in Profile 02 (Macau5). Probably these values are more expressive in Profile 03, because it does not present any natural structure of protection against the wave impacts, as the barrier island located at Ponta do Tubarão, or the sand banks in front of Macau5. The transport of the sediments occurs from East to West, and the sand accumulation is more pronounced on Profile 03 intertidal zone, where there are embrionary dunes in dryer months. The tidal currents speed, on the other hand, is more accentuated in the Macau5 area (Profile 02). At Ponta do Tubarão, the tidal currents presented a preferential direction for NE, at times of flood, currents and for NW, at times of ebb current; at Barra do Corta-Cachorro the direction of the currents were predominantly for NW, independent of the tide phase, coinciding with the preferential direction of the longshore current. This currents inversion at Ponta do Tubarão is attributed to the presence of the Ponta do Tubarão island barrier and by the communication channel of the lagoon with the sea. The tide currents are better observed in protected areas, as in the Ponta do Tubarão, when they present inversion in their direction accordingly to the flood and ebb tide. In open areas, as in Barra do Corta-Cachorro, the tide currents are overprinted by the longshore currents. Sediment analysis does not show important modifications in grain size related to seasonality (dry- and rainy seasons). On the foreshore and backshore zones, the sediments vary from fine to medium sand, while in the shoreface they very from fine to very sands. The grains are mostly spheres, varying from sub rounded to sub angled. Quartz is the main component alongside Feldspat and heavy minerals as accessory components. Biogenic content is also present and mainly represented by mollusks fragments. The calculated sediment transport show values around 100 m3/day. The morphodynamic studies indicated that this is a reflexive area from October to April, and intermediate from May to September. The Relative Tide Range-RTR for this area is 4 < RTR < 15, and so classified in the mixed wave-tide group. Having this exposed we can affirm that the more active natural factors in this area are the currents, followed by the tides and the winds. The anthropic factors are exclusively local and punctual (Macau and Serra Oil Field). Taking in account the economic importance of the area, as well as the intensity of coastal processes acting on this shore, it is important a continuity of the monthly environmental monitoring looking for variations on longer-period cycles. These data have been stored on the geo-referenced database of the projects MARPETRO and PETRORISCO (REDE 05), aiming to model the coastal and sea environment, susceptible to oil spills and their derivatives

Geologia, Geocronologia, Geoquímica e Petrogênese das Rochas Ígneas Cretácicas da Província Magmática do Cabo e suas Relações com as Unidades Sedimentares da Bacia de Pernambuco (NE do Brasil)

The area studied forms a thin NNE-directed belt situated south of Recife town (Pernambuco state), northeastern Brazil. Geologically, it comprises the Pernambuco Basin (PB), which is limited by the Pernambuco Lineament to the north, the Maragogi high to the south and the Pernambuco Alagoas massif to the west, all of them with Precambrian age. This thesis reports the results obtained for the Cabo Magmatic Province (CMP), aiming the characterization of the geology, stratigraphy, geochronology, geochemistry and petrogenesis of the Cretaceous igneous rocks presented in the PB. The PB is composed of the Cabo Formation (rift phase) at the base (polymictic conglomerates, sandstones, shales), an intermediate unit, the Estiva Formation (marbles and argillites), and, at the top, the Algodoais Formation (monomictic conglomerates, sandstones, shales). The CMP is represented by trachytes, rhyolites, pyroclastics (ignimbrites), basalts / trachy-andesites, monzonites and alkali-feldspar granite, which occur as dykes, flows, sills, laccoliths and plugs. Field observations and well descriptions show that the majority of the magmatic rocks have intrusive contacts with the Cabo Formation, although some occurrences are also suggestive of synchronism between volcanism and siliciclastic sedimentation. 40Ar/39Ar and zircon fission tracks for the magmatic rocks indicate an average age of 102 r 1 Ma for the CMP. This age represents an expressive event in the province and is detected in all igneous dated materials. It is considered as a minimum age (Albian) for the magmatic episode and the peak of the rift phase in the PB. The 40Ar/39Ar dates are about 10-14 Ma younger than published palynologic ages for this basin. Geochemically, the CMP may be divided in two major groups; i) a transitional to alkaline suite, constituted by basalts to trachy-andesites (types with fine-grained textures and phenocrysts of sanidine and plagioclase), trachytes (porphyrytic texture, with phenocrysts of sanidine and plagioclase) and monzonites; ii) a alkaline suite, highly fractionated, acidic volcano-plutonic association, formed by four subtypes (pyroclastic flows ignimbrites, fine-to medium-grained rhyolites, a high level granite, and later rhyolites). These four types are distinguished essentially by field aspects and petrographic and textural features. Compatible versus incompatible trace element concentrations and geochemical modeling based on both major and trace elements suggest the evolution through low pressure fractional crystallization for trachytes and other acidic rocks, whereas basalts / trachy-andesites and monzonites evolved by partial melting from a mantle source. Sr and Nd isotopes reveal two distinct sources for the rocks of the CMP. Concerning the acidic ones, the high initial Sr ratios (ISr = 0.7064-1.2295) and the negative HNd (-0.43 to -3.67) indicate a crustal source with mesoproterozoic model ages (TDM from 0.92 to 1.04 Ga). On the other hand, the basic to intermediate rocks have low ISr (0.7031-0.7042) and positive HNd (+1.28 to +1.98), which requires the depleted mantle as the most probable source; their model ages are in the range 0.61-0.66 Ga. However, the light rare earth enrichment of these rocks and partial melting modeling point to an incompatible-enriched lherzolitic mantle with very low quantity of garnet (1-3%). This apparent difference between geochemical and Nd isotopes may be resolved by assuming that the metasomatizing agent did not obliterate the original isotopic characteristics of the magmas. A 2 to 5% partial melting of this mantle at approximately 14 kbar and 1269oC account very well the basalts and trachy-andesites studied. By using these pressure and temperatures estimates for the generation of the basaltic to trachy-andesitic magma, it is determined a lithospheric stretching (E) of 2.5. This E value is an appropriated estimate for the sub-crustal stretching (astenospheric or the base of the lithosphere?) region under the Pernambuco Basin, the crustal stretching probably being lower. The integration of all data obtained in this thesis permits to interpret the magmatic evolution of the PB as follows; 1st) the partial melting of a garnet-bearing lherzolite generates incompatible-enriched basaltic, trachy-andesitic and monzonitic magmas; 2nd) the underplating of these basaltic magmas at the base of the continental crust triggers the partial melting of this crust, and thus originating the acidic magmas; 3rd) concomitantly with the previous stage, trachytic magmas were produced by fractionation from a monzonitic to trachy-andesitic liquid; 4th) the emplacement of the several magmas in superficial (e.g. flows) or sub-superficial (e.g. dykes, sills, domes, laccoliths) depths was almost synchronically, at about 102 r 1 Ma, and usually crosscutting the sedimentary rocks of the Cabo Formation. The presence of garnet in the lherzolitic mantle does not agree with pressures of about 14 kbar for the generation of the basaltic magma, as calculated based on chemical parameters. This can be resolved by admitting the astenospheric uplifting under the rift, which would place deep and hot material (mantle plume?) at sub-crustal depths. The generation of the magmas and their subsequent emplacement would be coupled with the crustal rifting of the PB, the border (NNE-SSW directed) and transfer (NW-SE directed) faults serving as conduits for the magma emplacement. Based on the E parameter and the integration of 40Ar/39Ar and palynologic data it is interpreted a maximum duration of 10-14 Ma for the rift phase (Cabo Formation clastic sedimentation and basic to acidic magmatism) of the PB

Métodos estatísticos recursivos aplicados ao problema de estimação de vazão de gás em plantas de Plunger-lift

This work has as main objective to find mathematical models based on linear parametric estimation techniques applied to the problem of calculating the grow of gas in oil wells. In particular we focus on achieving grow models applied to the case of wells that produce by plunger-lift technique on oil rigs, in which case, there are high peaks in the grow values that hinder their direct measurement by instruments. For this, we have developed estimators based on recursive least squares and make an analysis of statistical measures such as autocorrelation, cross-correlation, variogram and the cumulative periodogram, which are calculated recursively as data are obtained in real time from the plant in operation; the values obtained for these measures tell us how accurate the used model is and how it can be changed to better fit the measured values. The models have been tested in a pilot plant which emulates the process gas production in oil wells

Aplicação do método B ao projeto formal de software embarcado

This work shows a project method proposed to design and build software components from the software functional m del up to assembly code level in a rigorous fashion. This method is based on the B method, which was developed with support and interest of British Petroleum (BP). One goal of this methodology is to contribute to solve an important problem, known as The Verifying Compiler. Besides, this work describes a formal model of Z80 microcontroller and a real system of petroleum area. To achieve this goal, the formal model of Z80 was developed and documented, as it is one key component for the verification upto the assembly level. In order to improve the mentioned methodology, it was applied on a petroleum production test system, which is presented in this work. Part of this technique is performed manually. However, almost of these activities can be automated by a specific compiler. To build such compiler, the formal modelling of microcontroller and modelling of production test system should provide relevant knowledge and experiences to the design of a new compiler. In ummary, this work should improve the viability of one of the most stringent criteria for formal verification: speeding up the verification process, reducing design time and increasing the quality and reliability of the product of the final software. All these qualities are very important for systems that involve serious risks or in need of a high confidence, which is very common in the petroleum industry

Arquitetura hardware/software de um núcleo NCAP segundo o padrão IEEE 1451.1: uma prova de conceito

Os sensores inteligentes são dispositivos que se diferenciam dos sensores comuns por apresentar capacidade de processamento sobre os dados monitorados. Eles tipicamente são compostos por uma fonte de alimentação, transdutores (sensores e atuadores), memória, processador e transceptor. De acordo com o padrão IEEE 1451 um sensor inteligente pode ser dividido em módulos TIM e NCAP que devem se comunicar através de uma interface padronizada chamada TII. O módulo NCAP é a parte do sensor inteligente que comporta o processador. Portanto, ele é o responsável por atribuir a característica de inteligência ao sensor. Existem várias abordagens que podem ser utilizadas para o desenvolvimento desse módulo, dentre elas se destacam aquelas que utilizam microcontroladores de baixo custo e/ou FPGA. Este trabalho aborda o desenvolvimento de uma arquitetura hardware/software para um módulo NCAP segundo o padrão IEEE 1451.1. A infra-estrutura de hardware é composta por um driver de interface RS-232, uma memória RAM de 512kB, uma interface TII, o processador embarcado NIOS II e um simulador do módulo TIM. Para integração dos componentes de hardware é utilizada ferramenta de integração automática SOPC Builder. A infra-estrutura de software é composta pelo padrão IEEE 1451.1 e pela aplicação especí ca do NCAP que simula o monitoramento de pressão e temperatura em poços de petróleo com o objetivo de detectar vazamento. O módulo proposto é embarcado em uma FPGA e para a sua prototipação é usada a placa DE2 da Altera que contém a FPGA Cyclone II EP2C35F672C6. O processador embarcado NIOS II é utilizado para dar suporte à infra-estrutura de software do NCAP que é desenvolvido na linguagem C e se baseia no padrão IEEE 1451.1. A descrição do comportamento da infra-estrutura de hardware é feita utilizando a linguagem VHDL

Análises estratigráfica e estrutural da Seção Rifte (Valanginiano ao Barremiano) na área do levantamento sísmico 3D de baixo vermelho, Bacia Potiguar emersa

Baixo Vermelho area, situated on the northern portion of Umbuzeiro Graben (onshore Potiguar Basin), represents a typical example of a rift basin, characterized, in subsurface, by the sedimentary rift sequence, correlated to Pendência Formation (Valanginian-Barremian), and by the Carnaubais fault system. In this context, two main goals, the stratigraphic and the structural analysis, had guided the research. For this purpose, it was used the 3D seismic volume and eight wells located in the study area and adjacencies. The stratigraphic analysis of the Valanginian-Barremian interval was carried through in two distinct phases, 1D and 2D, in which the basic concepts of the sequence stratigraphy had been adapted. In these phases, the individual analysis of each well and the correlation between them, allowed to recognize the main lithofacies, to interpret the effective depositional systems and to identify the genetic units and key-surfaces of chronostratigraphic character. The analyzed lithofacies are represented predominantly by conglomerates, sandstones, siltites and shales, with carbonate rocks and marls occurring subordinately. According to these lithofacies associations, it is possible to interpret the following depositional systems: alluvial fan, fluvio-deltaic and lacustrine depositional systems. The alluvial fan system is mainly composed by conglomerates deposits, which had developed, preferentially in the south portion of the area, being directly associated to Carnaubais fault system. The fluvial-deltaic system, in turn, was mainly developed in the northwest portion of the area, at the flexural edge, being characterized by coarse sandstones with shales and siltites intercalated. On the other hand, the lacustrine system, the most dominant one in the study area, is formed mainly by shales that could occur intercalated with thin layers of fine to very fine sandstones, interpreted as turbidite deposits. The recognized sequence stratigraphy units in the wells are represented by parasequence sets, systems tracts and depositional sequences. The parasequence sets, which are progradational or retrogradational, had been grouped and related to the systems tracts. The predominance of the progradation parasequence sets (general trend with coarsening-upward) characterizes the Regressive Systems Tract, while the occurrence, more frequently, of the retrogradation parasequence sets (general trend with finning-upward) represents the Transgressive System Tract. In the seismic stratigraphic analysis, the lithofacies described in the wells had been related to chaotic, progradational and parallel/subparallel seismic facies, which are associated, frequently, to the alluvial fans, fluvial-deltaic and lacustrine depositional systems, respectively. In this analysis, it was possible to recognize fifteen seismic horizons that correspond to sequence boundaries and to maximum flooding surfaces, which separates Transgressive to Regressive systems tracts. The recognition of transgressive-regressive cycles allowed to identify nine, possibly, 3a order deposicional sequences, related to the tectonic-sedimentary cycles. The structural analysis, in turn, was done at Baixo Vermelho seismic volume, which shows, clearly, the structural complexity printed in the area, mainly related to Carnaubais fault system, acting as an important fault system of the rift edge. This fault system is characterized by a main arrangement of normal faults with trend NE-SO, where Carnaubais Fault represents the maximum expression of these lineations. Carnaubais Fault corresponds to a fault with typically listric geometry, with general trend N70°E, dipping to northwest. It is observed, throughout all the seismic volume, with variations in its surface, which had conditioned, in its evolutive stages, the formation of innumerable structural features that normally are identified in Pendencia Formation. In this unit, part of these features is related to the formation of longitudinal foldings (rollover structures and distentional folding associated), originated by the displacement of the main fault plan, propitiating variations in geometry and thickness of the adjacent layers, which had been deposited at the same time. Other structural features are related to the secondary faultings, which could be synthetic or antithetic to Carnaubais Fault. In a general way, these faults have limited lateral continuity, with listric planar format and, apparently, they play the role of the accomodation of the distentional deformation printed in the area. Thus, the interaction between the stratigraphic and structural analysis, based on an excellent quality of the used data, allowed to get one better agreement on the tectonicsedimentary evolution of the Valanginian-Barremian interval (Pendência Formation) in the studied area

Estudo integrado de análogo a reservatórios petrolíferos fluviais: caracterização, parametrização e modelagem tridimensional de depósitos recentes do Rio Assu (Rio Grande do Norte/Brasil)

This work shows a integrated study of modern analog to fluvial reservoirs of Açu Formation (Unit 3). The modern analog studied has been Assu River located in the same named city, Rio Grande do Norte State, Northeast of Brazil. It has been developed a new methodology to parameterizating the fluvial geological bodies by GPR profile (by central frequency antennas of 50, 100 and 200 MHz). The main parameters obtained were width and thickness. Still in the parameterization, orthophotomaps have been used to calculate the canal sinuosity and braided parameters of Assu River. These information are integrated in a database to supply input data in 3D geological models of fluvial reservoirs. It was made an architectural characterization of the deposit by trench description, GPR profile interpretation and natural expositions study to recognize and describe the facies and its associations, external and internal geometries, boundary surfaces and archtetural elements. Finally, a three-dimensional modeling has been built using all the acquired data already in association with real well data of a reservoir which Rio Assu is considered as analogous. Facies simulations have been used simple kriging (deterministic algorithm), SIS and Boolean (object-based, both stochastics). And, for modeling porosities have used the stochastic algorithm SGS

Estratigrafia de sequências do intervalo aptiano ao albino na Bacia do Araripe, NE do Brasil

This study has as a main objective to make a detailed stratigraphic analysis of the Aptian-Albian interval in the east part of Araripe Basin, NE of Brazil which correspond, litostratigraphically, to Rio Da Batateira, Crato, Ipubi and Romualdo formations. The stratigraphic analysis was based on three different stages, the 1D, 2D and 3D analysis; these ones were adapted to the sequence stratigraphy concepts in order to create a chronostratigraphic framework for the study area within the basin. The database used in the present study contains field and well information, wells that belong to Santana Project, carried out by the Ministério de Minas e Energia- DNPM- CPRM from 1977 to 1978. The analysis 1D, which was done separately for each well and outcrop allowed the recognition of 13 sedimentary facies, mainly divided based on predominant litologies and sedimentary structures. Such facies are lithologically represented by pebble, sandstones, claystones, margas and evaporates; these facies are associated in order to characterize different depositional systems, that integrate from the continental environment (fluvial system and lacustre), paralic system (delta system and lagunar) to the marine environment (shelfenvironment). The first one, the fluvial system was divided into two subtypes: meandering fluvial system, characterized by fill channel and floodplain deposits; the facies of this system are associated vertically according to the textural thinning upward cycles (dirting-up trend pattern in well logs). Lacustrine environment is mainly related with the lithotypes of the Crato Formation, it shows a good distribution within the basin, been composed by green claystone deposits and calcareous laminated. Deltaic System represented by prodelta and delta front deposits which coarsening upward tendency. Lagunar system is characterised by the presence of anhydrite and gypsum deposits besides the black claystone deposits with vegetal fragments which do not contain a fauna typically marine. The marine platform system is composed by successions of black and gray claystone with fossiliferous fauna of Dinoflagellates (Spiniferites Mantell, Subtilisphaera Jain e Subtilisphaera Millipied genre) typical of this kind of depositional system. The sedimentary facies described are vertically arranged in cycles with progradational patterns which form textural coersening upward cycles and retrogradational, represented by textural thinning dowward cycles. Based in these cycles, in their stack pattern and the vertical change between these patterns, the systems tracks and the depositional sequences were recognized. The Low System Track (LST) and High System Track (HST) are composed by cycles with progradational stack pattern, whereas the Trangessive System Track (TST) is composed by retrogradational stack pattern cycles. The 2D stratigraphic analysis was done through the carrying out of two stratigraphic sections. For the selection of the datum the deepest maximum flooding surface was chosen, inside the Sequence 1, the execution of these sections allowed to understand the behaviour of six depositional systems along the study area, which were interpreted as cycles of second order or supercycles (cycles between 3 and 10 Ma), according to the Vail, et al (1977) classification. The Sequence 1, the oldest of the six identified is composed by the low, transgressive and high systems tracks. The first two system tracks are formed exclusively by fluvial deposits of the Rio da Batateira Formation whereas the third one includes deltaic and lacustrine deposits of the Crato Formation. The sequences 2 and 3 are formed by the transgressive systems tracks (lake spreading phase) and the highstand system track (lake backward phase). The TST of these sequences are formed by lacustrine deposits whereas HST contains deltaic deposits, indicating high rates of sedimentary supply at the time of it s deposition. The sequence 4 is composed by LST, TST and HST, The TST4 shows a significant fall of the lake base level, this track was developed in conditions of low relation between the creation rate of space of accommodation and the sedimentary influx. The TST4 marks the third phase of expansion of the lacustrine system in the section after the basin´s rift, the lacustrine system established in the previous track starts a backward phase in conditions that the sedimentary supply rate exceeds the creation rate of space accommodation. The sequence 5 was developed in two different phases, the first one is related with the latest expansion stage of the lake, (TST5), the basal track of this sequence. In this phase the base level of the lake rose considerably. The second phase (related to the TST5) indicates the end of the lacustrine domain in the Araripe Basin and the change to lagunar system ant tidal flat, with great portions in the supratidal. These systems were formed by restricted lagoons, with shallow level of water and with intermittent connections with the sea. This, was the phase when the Araripe Basin recorded the most several arid conditions of the whole interval studied, Aptian Albian, conditions that allow the formation of evaporitic deposits. The sequence 6 began its deposition after a significant fall of the sea (LST6). The sequence 6 is without any doubtlessly, the sequence that has deposits that prove the effective entrance of the sea into the Araripe Basin. The TST6, end of this sequence, represents the moment which the sea reaches its maximum level during the Aptian Albian time. The stratigraphic analysis of the Aptian Albian interval made possible the understanding that the main control in the development of the depositional sequences recognized in the Araripe Basin were the variations of the local base level, which are controlled itself by the climate changes

As relações entre tectonismo e seqüências deposiconais no rifte potiguar - porção SW do Graben de Umbuzeiro, bacia potiguar emersa

Through an integrated approach, using litho, chrono and biostratigraphic data, the relative importance of climate variations and tectonics were recognized in rift sediments of the onshore Potiguar Basin, Northeast Brazil. Concepts of sequence stratigraphy were applied as a template to integrate sedimentological and geochemical data (oxygen isotopes), as well as quantitative palynologic methods to address and recognize the main depositional patterns produced in a rift basin. The main objective was to address the relative importance of climate changes and tectonics to the resultant stratigraphic architecture. The results of computer simulations of sedimentary basin fills of rift basins were quite useful to test working hypothesis and mimic the process of filling a half graben during a rift event. The studied section includes a neovalanginian-eobarremian (Lower Cretaceous) rift interval from the Pendência Formation, located in the southwestern portion of Umbuzeiro Graben, in the offshore Potiguar Basin. The depositional setting is interpreted as progradational deltaic system entering a lake from its flexural margin. Sismoestratigraphyc and well logs analyses allowed to interpret two regressive intervals (Green and Yellow Sequences), separated by a broad transgressive interval (Orange Sequence), known as the Livramento Shale. The depositional history encompass three stages: two tectonically active phases, during the deposition of the Green and Yellow Sequences, and a tectonically quiescent phase, during the deposition of the Orange Sequence. Paleoclimatic interpretation, based on quantitative palynology and geochemical data (��18O), suggests a tendency to arid conditions during the tectonically active phases and wet conditions during the tectonically quiescent phase. Stratigraphic modeling and backstripping techniques, supported by paleoclimatic/paleoecologic interpretations provide a powerful methodology to evaluate the tectonic and climatic controls on tectonic lakes

Mapeamento digital de análogos a reservatórios petrolíferos: exemplos para depósitos fluviais da Unidade Açu-3 - Bacia Potiguar

In the current work are presented the results about the study of digital mapping of analogs referents the fluvial oil reservoirs in the Açu Formation. With the regional recognizing in the south corner of Potiguar Basin was selected a area of 150 Km square in the west of Assu city. In this area was chosen the outcrops for the digital mapping and from the data fields and remote sensors were done the depositional architectural for the fluvial deposits, which it was named coarse meandering fluvial systems. In the deposits were individualized 3 (three) fluvial cycles, which they was separated by bounding surface of fifth order. Such cycles are preferentially sandy, with fining-upward sequence finished in flood plain deposits. Inner of the sandy levels of the filling channels were characterized least cycles, normaly incomplete, constituted by braided sandy bodies and bounding surfaces of fourth order. In the mapped area was chosen a outcrop with great exposition, where it was possible to see tipical deposits of filling channel and was in this outcrop that was done the digital mapping. In this outcrop was used diverse technics and tools, which they integrated sedimentological, altimetric (GPS, Total Station), LIDAR (Light Detection and Ranging), digital photomosaic of high resolution and of the inner geometries (Ground Penetration Radar) data sets. For the integrating, interpretation and visualization of data was used software GoCAD®. The final product of the outcrop digital mapping was the photorealistic model of part of the cliff (or slope) because the observed reflectors in the radargrams were absents. A part of bar oblique accretion was modeled according to GPR gride of 200x200 meters in the alluvial Assu river probable recent analog. With the data of inner geometries was developed the three-dimentional sedimentary architectural, where it was possible characterize sand sheet deposits and many hierarchy of braided channels. At last, simulations of sedimentary geometries and architectures of the Potiguar Basin Fluvial Reservoirs were done with PetBool software, in order to understand the capacity of this program in simulations with a lot of numbers of conditioning wells. In total, 45 simulations was acquired, where the time and the channel numbers increase in relation of the conditioning wells quantity. The deformation of the meanders was detected from the change of simulated dominion dimensions. The presence of this problem was because the relationship between the simulated dominion and the width of the meander

Dobramentos distensionais e a geometria da falha de Baixa Grande, Graben de Umbuzeiro, Bacia Potiguar (RN)

In spite of significant study and exploration of Potiguar Basin, easternmost Brazilian equatorial margin, by the oil industry, its still provides an interesting discussion about its origin and the mechanisms of hydrocarbon trapping. The mapping and interpretation of 3D seismic reflection data of Baixa Grande Fault, SW portion of Umbuzeiro Graben, points as responsible for basin architecture configuration an extensional deformational process. The fault geometry is the most important deformation boundary condition of the rift stata. The development of flat-ramp geometries is responsible for the formation of important extensional anticline folds, many of then hydrocarbon traps in this basin segment. The dominant extensional deformation in the studied area, marked by the development of normal faults developments, associated with structures indicative of obliquity suggests variations on the former regime of Potiguar Basin through a multiphase process. The changes in structural trend permits the generation of local transpression and transtension zones, which results in a complex deformation pattern displayed by the Potiguar basin sin-rift strata. Sismostratigraphic and log analysis show that the Baixa Grande Fault acts as listric growing fault at the sedimentation onset. The generation of a relay ramp between Baixa Grande Fault and Carnaubais Fault was probably responsible for the balance between subsidence and sedimentary influx taxes, inhibiting its growing behaviour. The sismosequences analysis s indicates that the extensional folds generation its diachronic, and then the folds can be both syn- and post-depositional

Iinterpretação conjunta de dados de GPR e medidas de permeabilidade sobre um análogo de reservatório siliciclástico falhado na bacia de Tucano, no NE do Brasil

It is presented an integrated geophysical investigation of the spatial distribution of faults and deformation bands (DB´s) in a faulted siliciclastic reservoir analogue, located in Tucano Basin, Bahia State, northeastern Brazil. Ground Penetrating Radar (GPR) and permeability measurements allowed the analysis of the influence of DB´s in the rock permeability and porosity. GPR data were processed using a suitable flow parametrization in order to highlight discontinuities in sedimentary layers. The obtained images allowed the subsurface detection of DB´s presenting displacements greater that 10 cm. A good correlation was verified between DB´s detected by GPR and those observed in surface, the latter identified using conventional structural methods. After some adaptations in the minipermeameter in order to increase measurement precision, two approaches to measure permeabilities were tested: in situ and in collected cores. The former approach provided better results than the latter and consisted of scratching the outcrop surface, followed by direct measurements on outcrop rocks. The measured permeability profiles allowed to characterize the spatial transition from DB´s to undeformed rock; variation of up to three orders of magnitude were detected. The permeability profiles also presented quasi-periodic patterns, associated with textural and granulometric changes, possibly associated to depositional cycles. Integrated interpretation of the geological, geophysical and core data, provided the subsurface identification of an increase in the DB´s number associated with a sedimentary layer presenting granulometric decrease at depths greater than 8 m. An associated sharp decrease in permeability was also measured in cores from boreholes. The obtained results reveal that radagrams, besides providing high resolution images, allowing the detection of small structures (> 10 cm), also presented a correlation with the permeability data. In this way, GPR data may be used to build upscaling laws, bridging the gap between outcrop and seismic data sets, which may result in better models for faulted reservoirs