Rodrigo Bagueira de Vasconcellos Azeredo

• DSc
• Professor (Associate) at Fluminense Federal University

This study focuses on the laboratory-scale petrophysical characterization of sandstones from the Rio Bonito Formation (Lower Permian), Paraná Basin, carried out from drill core samples from well PN-14-SC.02 obtained by CPRM-Brazilian Geological Service in the 1980s on the eastern edge of the Basin. This study includes integrating experimental data...

Nuclear magnetic resonance (NMR) techniques are key in the study of porous reservoir rocks. They can provide valuable insight into the pore size distribution of the pore space of a given rock sample due to its dependence on the magnetic fluid/matrix interaction. The pore space is often studied at the μm scale through the use of micro-CT images, whi...

NMR techniques are key in the study of porous reservoir rock, both experimentally and numerically. The T2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$T_2$$\end{docum...

Nuclear Magnetic Resonance (NMR) is an important tool to assess physical quantities that characterize porous media such as reservoir rocks. Information about surface-to-volume ratio and micro-connectivity, for instance, are coded in the time-dependent diffusion coefficient of magnetized spins. In this work, we present an efficient computational imp...

The estimation of continuous downhole permeability is widely performed by nuclear magnetic resonance (NMR) using the classical Seevers-Kenyon and Timur-Coates models. The first approach uses an average of the relaxation times, whereas the latter approach is based on the fractional fluid content computed from a relaxation time distribution cutoff. H...

We present a new formulation to determine permeability in reservoir core rocks based on the spatial encoding of the magnetic field used in the NMR technique. The variations of the magnetic field generate multiples T2 spectra in one sample, creating a representative data of porosity distribution. In this study, each T2 spectrum was called “magnetic...

Reliable estimates of porosity can be obtained from different types of geophysical well logs. However, obtaining in situ permeability estimates is still a major challenge in the geosciences. This work aims to evaluate the application of data mining techniques to NMR logs for rock permeability classification, thus far tested only on laboratory data....

Permeability is a parameter that measures the resistance that fluid faces when flowing through a porous medium. Usually, this parameter is determined in routine laboratory tests by applying Darcy’s law. Those tests can be complex and time-demanding, and they do not offer a deep understanding of the material internal microstructure. Currently, with...

To characterize a porous medium, it is essential to determine the geometry of its pore space as it controls key properties such as permeability. A standard approach is to saturate the pore space with a fluid and perform NMR relaxation measurements. The standard measurements are sensitive to the low-lying diffusion eigen-modes and they allow an esti...

This paper reports the droplet size distribution (DSD) measurements in 28 W/O (water/oil) crude oil emulsions prepared with two Brazilian oils (medium and heavy) under different shear conditions using both 10 g L-1 NaCl solution and water production by low field nuclear magnetic resonance (NMR, 2.2 MHz). The PFGSTE (pulsed-field gradient-stimulated...

In a previous work, we showed how to obtain the surface relaxivity as a function of pore size. In the present work, we take a step further and introduce a formulation that uses this surface relaxivity function to convert a T2 distribution into a pore size distribution. We then compare the pore size distribution obtained with the aid of this formula...

Progressive structural deterioration of an endodontic instrument – A preliminary micro-computed tomography study Igor Bastos Barbosaa, Pantaleo Scelza, André Maues Brabo Pereirab, Fabiano Guerra Ferreira, Rodrigo Bagueira, Caroline Sousa Ribeiro Adeodatoa, Miriam Zaccaro Scelza, Department of Endodontics, Fluminense Federal University (UFF), Rua M...

Aim: Cancer has emerged as a growing public health problem in many parts of the world. Methodology: We describe the synthesis of a series of carbohydrate-based isoquinoline-5,8-diones through the 1,4-addition reaction between 5,8-dioxo-5,8-dihydroisoquinoline and aminocarbohydrates. Halogenated quinones were also synthesized. Their inhibitory ef...

A determinação da permeabilidade das rochas reservatório apresenta um papel de alta relevância no processo decisório de escolha de uma região exploratória de hidrocarbonetos. O objetivo deste trabalho foi o desenvolvimento e aplicação de um modelo de permeabilidade, denominado K ON, para a determinação dos valores de permeabilidade de rochas reserv...

O conhecimento da distribuição dos espaços vazios em uma rocha, ou seja, de seu sistema poroso, apresenta-se como uma importante ferramenta no apoio as pesquisas em geologia, petrofísica, e áreas do conhecimento relacionadas. A heterogeneidade na distribuição de poros em rochas reservatório é um parâmetro auxiliar em métodos de estimação da permeab...

A Formação Rio Bonito localiza-se na Bacia do Paraná, sendo constituída por sedimentos cíclicos de arenitos, siltitos e folhelhos, além de possuir grandes extensões de depósitos de carvão mineral encontradas entre as cidades de Lauro Muller, Guatá e São Joaquim, todas no estado de Santa Catarina. A história sedimentar é iniciada com a subsidência d...

The recent major discoveries of petroleum in Pre-Salt carbonate reservoirs, of mainly lacustrine origin, offshore Brazil has increased interest in studying these complex non-marine reservoirs, which present many production-development challenges, largely due to their heterogeneous nature. Some of the reservoir carbonate rock-types present in Brazil...

Permeability is a key property to state if producing fluids from a hydrocarbon reservoir will be feasible or not. Nevertheless, the accurate estimation of permeability in carbonate rock reservoirs is considered a challenging task. This is due to two main reasons: (i) the extreme heterogeneity typically contained in these kinds of rocks; (ii) the fa...

Os carbonatos são o principal litotipo rochoso de armazenamento de óleo nos sistemas petrolíferos mundiais. O presente trabalho tem por objetivo correlacionar os processos de dolomitização com as propriedades petrofísicas de porosidade e permeabilidade dos carbonatos do pré-sal brasileiro. Para o estudo foram utilizados 10 plugues (cilindros de ~3,...

In the present work, we describe our experience with digital petrophysics, enhancing our choices for performing the related tasks. The focus is on the use of ordinary personal computers. To our best knowledge, some of the information and hints we give cannot be found in the literature and we hope they may be useful to researchers that intend to wor...

In the present work, we formulate and solve an inverse problem to recover the surface relaxivity as a function of pore size. The input data for our technique are the distribution measurement and the micro-tomographic image of the rock sample under investigation. We simulate the NMR relaxation signal for a given surface relaxivity function using the...

Recent studies have indicated that the accurate identification of carbonate rock types in a reservoir can be employed as a preliminary step to enhance the effectiveness of petrophysical property modeling. Furthermore, rock typing activity has been shown to be of key importance in several steps of formation evaluation, such as the study of sedimenta...

The effect of the selection of different nuclear magnetic resonance (NMR) relaxation times for permeability estimation is investigated for a set of fully brine-saturated rocks acquired from Cretaceous carbonate reservoirs in the North Sea and Middle East. Estimators that are obtained from the relaxation times based on the Pythagorean means are comp...

The Presalt carbonate wells of Lula Field, Santos Basin, Offshore Brazil, are currently producing high quality, 28 to 30° API oil at an average rate of 30,000 BOPD. With reservoir pressures over 8,000 psi, and a downhole oil viscosity of 1 cP, the proli¿c Àow rates from these high permeability, lacustrine carbonates have shown no signi¿cant decline...

In this work, we evaluate two pore volume compressibility models that are currently discussed in the literature (Horne, 1990; Jalalh, 2006b). Five groups of carbonate rock samples from the three following sedimentary basins in North America that are known for their association with hydrocarbon deposits were selected for this study: (i) the Guelph F...

Chemical investigation of the CH2Cl2 crude extract from the brown alga Canistrocarpus cervicornis (Dictyotaceae) led to isolation of one new (1) and four previously reported dolastane diterpenes (2–5). Their structures were characterized by 1D- and 2D-NMR spectroscopic techniques, including a full single crystal X-ray diffraction analysis for 1, 2,...

Information coming from different porosity systems in carbonate reservoirs is of great importance in reservoir engineering and rock petrophysics. In this study, we use the information of carbonate samples (plugs), representing some porosity systems, such as intercrystalline, intergrain, moldic, vuggy and fracture. Porosity was measured as fraction...

Nuclear magnetic resonance (NMR) logging is widely used for continuous downhole permeability estimates. But long before NMR, laboratory measurements of capillary pressure curves were used for the same purpose. Remarkably, the mercury injection capillary pressure (MICP) technique was developed for predicting the permeability of small and irregular-s...

Based on the Kozeny-Carman equation, continuous downhole permeability estimation is widely performed by nuclear magnetic resonance (NMR) using the classical approaches of Seevers-Kenyon and Timur-Coates. While the primer approach uses an average of the relaxation times, the latter approach is based on the fractional fluid content computed from the...

The accurate permeability mapping, even with the aid of modern borehole geophysics methods, is still a big challenge on the reservoir management framework. One concern within the petrophysics community is that rock permeability value predicted by well logging should not be considered as absolute, mainly for carbonates, but a relative index for iden...

Chemical investigation on the nonpolar extract of the Brazilian brown alga Canistrocarpus cervicornis (Dictyotaceae)has led to the isolation of anew diterpene 1 and four known seco-dolastane diterpenes 2 – 5.Their chemical structures were elucidated by 1D- and 2D-NMR spectroscopy, and the data was compared with the literature. A full X-ray diffract...

The quantification of phases in rock samples is a useful and important subject in geology. However, due to complexity of the method and proper sample preparation Rietveld refinement techniques are not yet widespread. Therefore, the goal of this study is to test rock sample preparation for Rietveld refinement to obtain trustworthy mineralogical quan...

Digital Rock Physics (DRP) is an interdisciplinary area which consists in imaging and digitizing the matrix of a natural rock and then, numerically, simulating its physical processes. These virtual numerical experiments can describe several types of rock macroscopic properties such as permeability, electrical conductivity and elastic modulus. We de...

Nuclear magnetic resonance (NMR) measurements have been used as a way to evaluate reservoir rocks based, on the longitudinal and transverse relaxation times, T1 and T2, and the time dependent diffusion coefficient, D(t). Relaxation time distributions can be related to pore sizes and to the free and bound fluid fractions. In addition, there are well...

In this paper, a comparative study was performed of nuclear magnetic resonance (NMR) permeability estimators under different relaxation time selections. We evaluated a set of laboratorial NMR transverse relaxation time (T2) measurements of fully brine-saturated Cretaceous diagenetic chalks. Classical Pythagorean means (harmonic, geometric and arith...

Although nuclear magnetic resonance (NMR) is one of the most powerful analytical techniques, it has not been widely used as a non-destructive, non-contact inline industrial sensor. A short background of NMR spectroscopy fundamentals and instrumentation is presented along with its potential applications and limitations for real-time analysis in the...

Solvent suppression is frequently mandatory in 1H high-resolution nuclear magnetic resonance (NMR), especially for those experiments designed for non-deuterated solvent, normally used in protein and in vivo analysis, and also in liquid chromatography-NMR. Here, simple pulse sequences, which are based on continuous wave free precession (CWFP), consi...

When estimating permeability (k) from NMR logs, a key assumption is that the surface relaxivity (rho2) parameter, which scales the relationship between transverse relaxation time (T2) and the surface-to-volume ratio (S/V) of the pore system, remains constant. With this assumption, the rho2 parameter can be accounted for in the premultiplier of the...

The safe use of herbal medicines requires prior authentication of the raw materials used to make them. This is an important step, since the ingestion of herbal preparations or extracts can cause serious health problems. Among the different analytical techniques, nuclear magnetic resonance (NMR) spectroscopy has the advantage of being non-invasive a...

Existing carbonate classification schemes are based on quantifying rock texture by grain size or pore-throat size. They were developed from visual inspection of cores and cuttings, thin-section microscopy or mercury porosimetry. Recent advances in NMR log and core analysis, complemented by more quantitative use of borehole image logs, have led to t...

In the present investigation, we studied the enzymatic synthesis of monoacylglycerols (MAG) and diacylglycerols (DAG) via the esterification of saturated fatty acids (stearic, palmitic and an industrial residue containing 87% palmitic acid) and glycerol in a solvent-free system. Three immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym...

Time-domain nuclear magnetic resonance (TD-NMR) is one of the most popular solutions for quality control in the food industry. Despite the recognized success of TD-NMR in quality control and quality assurance, the speed by which samples can be characterized by TD-NMR techniques is still a concern, primarily when considering online or high-throughpu...

This study explores the application of the partial least squares regression (PLSR) technique to rock permeability prediction from nuclear magnetic resonance (NMR) relaxation data. A total of 68 Brazilian sandstone cores selected from reservoirs and outcrop analogs were fully saturated and analyzed by NMR. The permeability of the cores ranged from 0...

This study explores the application of Partial Least Squares Regression (PLSR) in modeling rock permeability from Nuclear Magnetic Resonance (NMR) relaxation data. The 1H transversal relaxation T2 curves of 68 sandstone core plugs from outcrop analogues and Brazilian reservoirs, with permeability ranging from 0.007 to 9,800 mD and fully saturated w...

The transesterification reaction used to produce biodiesel was monitored with 1H high-resolution nuclear magnetic resonance (HRNMR), conventional low-resolution NMR (LRNMR), and unilateral NMR (UNMR) spectroscopy. HRNMR was used as a standard method to compare with the methods of LRNMR and UNMR. A Carr–Purcell–Meiboom–Gill (CPMG) pulse sequence was...

The infections caused by the Herpes Simplex Virus are one of the most common sources of diseases in adults and several natural nucleoside analogues are currently used in the treatment of these infections. In vitro tests of a series of quinolonic ribonucleosides derivatives synthesized by part of our group indicated that some of them have antiviral...

O presente trabalho demonstra a aplicação da técnica de RMN na caracterização petrofísica de rochas reservatório. Para isso, foram medidos os tempos de relaxação (T1 e T2) e as constantes de difusão translacional (D) de 25 amostras de afloramentos, saturadas com solução salina. A partir dos dados de RMN, propriedades como porosidade, distribuição d...

Nuclear magnetic resonance studies of banana fragments during ripening show an increase on the water transverse relaxation time (T2) and a decrease in water self-diffusion coefficient (D). As T(2) and D are normally directly correlated, we studied these two properties in intact bananas during ripening, in an attempt to rule out the effect of injury...

This study explores the application of multivariate data analysis in the viscosity prediction of crude oils using NMR relaxation data. The 1H transverse relaxation times (T2) of 68 Brazilian crude oil samples, ranging from light to extra-heavy (2 to 30,000 cP), were measured at 2 MHz. Partial least squares regression (PLSR) models were developed to...

Six new nor-beta-lapachones have been synthesized from reaction of 3-bromo-nor-beta-lapachone with arylamines. These derivatives have potent anticancer properties against several cell lines. Here, we report complete unambiguous assignments of (1)H and (13)C chemical shifts of the new compounds. The assignments were made using a combination of one-...

This study explores the benefits of PLS (Partial Least Squares) regression in the permeability prediction from NMR relaxation data over the classical SDR (Schlumberger Doll Research) and Timur-Coates models based on the T2LMand FFI/BVI ratio, respectively. To pursue this case study, the transversal relaxation times (T2) of 13 Santos Basin low perme...

In a study of the vanadyl (VO2+)-humic acids system, the residual vanadyl ion suppressed fluorescence and specific electron paramagnetic resonance (EPR) and NMR signals. In the case of NMR, the proton rotating frame relaxation times (T1ρH) indicate that this suppression is due to an inefficient H-C cross polarization, which is a consequence of a sh...

CAMPHOR: A GOOD MODEL FOR ILLUSTRATING NMR TECHNIQUES. The use of Nuclear Magnetic Resonance spectroscopy to establish the three-dimensional structures of molecules is an important component of modern Chemistry courses. The combination of techniques that can be used for this purpose is conveniently illustrated by their application to the camphor mo...

The use of Nuclear Magnetic Resonance spectroscopy to establish the three-dimensional structures of molecules is an important component of modern Chemistry courses. The combination of techniques that can be used for this purpose is conveniently illustrated by their application to the camphor molecule. This paper presents applications of several tec...

Continuous wave free precession (CWFP) nuclear magnetic resonance is capable of yielding quantitative and easily obtainable information concerning the kinetics of processes that change the relaxation rates of the nuclear spins through the action of some external agent. In the present application, heat flow from a natural rubber sample to a liquid n...

The purpose of this communication is to describe a method for rapid and simultaneous determination of longitudinal (T 1) and transversel (T 2) relaxation times, based on a single continuous wave free precession (CWFP) experiment which employs RF pulses with a p/2 flip angle. We analyze several examples, involving nuclei such as 1 H, 31 P, and 19 F,...

The purpose of this communication is to describe a method for rapid and simultaneous determination of longitudinal (T1) and transversel (T2) relaxation times, based on a single continuous wave free precession (CWFP) experiment which employs RF pulses with a pi/2 flip angle. We analyze several examples, involving nuclei such as 1H, 31P, and 19F, whe...

The use of continuous wave free precession (CWFP) as a practical analytical tool for quantitative determinations in low-resolution nuclear magnetic resonance (LRNMR) is examined. The requirements of this technique are shown to be no more demanding than those prevailing in free-induction decay or spin-echo measurements. It is shown that the substant...

Composite resins used in dentistry have an organic matrix based on a blend of methacrylate monomers like BisGMA and derivatives, UDMA and TEGDMA, which harden by free radical polymerization. The polymerization process can be initiated by visible light. The rate of polymerization reaction plays an important role in the clinical performance of resin...

natural e grande constante magnetogírica como o H e F e com amostra grandes com até 150 ml. Com não se beneficia do efeito do deslocamento químico, suas aplicações se restringem as medidas de componentes totais (teor de hidrogênio em combustíveis e solventes) ou de componente parciais em amostras heterogêneas (medida de umidade, teor de óleo em pro...

Steady-state free precession (SSFP) of nuclear spins in the presence of a magnetic field gradient is known to be very sensitive to flow. We present a theoretical and experimental study of flow sensitivity in a regime where the spacing of the radio-frequency pulses is extremely short compared with the free induction decay time and the relaxation tim...

The use of steady-state free precession nuclear magnetic resonance (NMR) for quantitative analysis in low magnetic field is investigated and shown to exhibit substantial advantages compared to more conventional NMR methods. With only minor additional requirements, the technique permits a considerable increase in signal-to-noise ratio for a given ac...

Oil is a very complex multi-component system constituted by tens of thousands of different hydrocarbon molecules, and its 1 H NMR relaxation profile can be modeled as a linear combination of characteristic relaxation times from the measurable hydrogens present in their structure. [1, 2]. This work presents a study of different Brazilian crude oils...