Aplicação da destilação simulada por cromatografia gasosa e da termogravimetria para a avaliação da influência da redução do teor de enxofre sobre as propriedades físico-químicas do óleo diesel

One of the main problems related to the use of diesel as fuel is the presence of sulfur (S) which causes environmental pollution and corrosion of engines. In order to minimize the consequences of the release of this pollutant, Brazilian law established maximum sulfur content that diesel fuel may have. To meet these requirements, diesel with a maximum sulfur concentration equal to 10 mg/kg (S10) has been widely marketed in the country. However, the reduction of sulfur can lead to changes in the physicochemical properties of the fuel, which are essential for the performance of road vehicles. This work aims to identify the main changes in the physicochemical properties of diesel fuel and how they are related to reduction of sulfur content. Samples of diesel types S10, S500 and S1800 were tested according with the methods of the American Society for Testing and Materials (ASTM). The fuels were also characterized by thermogravimetric analysis (TG) and subjected to physical distillation (ASTM D86) and simulated distillation gas chromatography (ASTM D2887). The results showed that the reduction of sulfur turned the fuel lighter and fluid, allowing a greater applicability to low temperature environments and safer for transportation and storage. Through the simulated distillation data was observed that decreasing sulfur content resulted in higher initial boiling point temperatures and the decreasing of the boiling temperature of the medium and heavy fractions. Thermogravimetric analysis showed a loss event mass attributed to volatilization or distillation of light and medium hydrocarbons. Based on these data, the kinetic behavior of the samples was investigated and it was observed that the activation energies (Ea) did not show significant changes throughout conversion. Considering the average of these energies, the S1800 had the highest Ea during the conversion and the S10 the lowest values

Análise espacial de reservatórios usando DFA de dados geofísicos

This research aims to set whether is possible to build spatial patterns over oil fields using DFA (Detrended Fluctuation Analysis) of the following well logs: sonic, density, porosity, resistivity and gamma ray. It was employed in the analysis a set of 54 well logs from the oil field of Campos dos Namorados, RJ, Brazil. To check for spatial correlation, it was employed the Mantel test between the matrix of geographic distance and the matrix of the difference of DFA exponents of the well logs. The null hypothesis assumes the absence of spatial structures that means no correlation between the matrix of Euclidean distance and the matrix of DFA differences. Our analysis indicate that the sonic (p=0.18) and the density (p=0.26) were the profiles that show tendency to correlation, or weak correlation. A complementary analysis using contour plot also has suggested that the sonic and the density are the most suitable with geophysical quantities for the construction of spatial structures corroborating the results of Mantel test

Otimização dos parâmetros de um modelo de bomba em sistemas de bombeio centrífugo submerso

One of several techniques applied to production processes oil is the artificial lift, using equipment in order to reduce the bottom hole pressure, providing a pressure differential, resulting in a flow increase. The choice of the artificial lift method depends on a detailed analysis of the some factors, such as initial costs of installation, maintenance, and the existing conditions in the producing field. The Electrical Submersible Pumping method (ESP) appears to be quite efficient when the objective is to produce high liquid flow rates in both onshore and offshore environments, in adverse conditions of temperature and in the presence of viscous fluids. By definition, ESP is a method of artificial lift in which a subsurface electric motor transforms electrical into mechanical energy to trigger a centrifugal pump of multiple stages, composed of a rotating impeller (rotor) and a stationary diffuser (stator). The pump converts the mechanical energy of the engine into kinetic energy in the form of velocity, which pushes the fluid to the surface. The objective of this work is to implement the optimization method of the flexible polyhedron, known as Modified Simplex Method (MSM) applied to the study of the influence of the modification of the input and output parameters of the centrifugal pump impeller in the channel of a system ESP. In the use of the optimization method by changing the angular parameters of the pump, the resultant data applied to the simulations allowed to obtain optimized values of the Head (lift height), lossless efficiency and the power with differentiated results.

Recuperação avançada de óleos pesados em poços fraturados utilizando aquecimento eletromagnético indutivo

The success achieved by thermal methods of recovery, in heavy oils, prompted the emergence of studies on the use of electromagnetic waves as heat generating sources in oil reservoirs. Thus, this generation is achieved by three types of different processes according to the frequency range used. They are: the electromagnetic induction heating, the resistive and the dielectric, also known as radiation. This study was based on computer simulations in oil reservoirs with characteristics similar to those found in the sedimentary basins of the Brazilian Northeast. All cases studied were simulated using the software STARS, CMG (Computer Group, version 2012.10 Modeling). Some simulations took into account the inclusion of electrically sensitive particles in certain sectors of the reservoir model studied by fracturing. The purpose of this work is the use of the electromagnetic induction heating as a recovery method of heavy oil, to check the influence of these aforementioned particles on the reservoir model used. Comparative analyses were made involving electromagnetic induction heating, the operation of hydraulic fracturing and the injection of water to the different situations of the reservoir model studied. It was found that fracturing the injection well in order that the electromagnetic heating occurs in the same well where there is water injection, there was a considerable increase in the recovery factor and in the cumulative oil production in relation to the models in which hydraulic fracturing occurred in the production well and water injection in the injection well. This is due to the generation of steam in situ in the reservoir.

Fluxo de fluído através de um meio poroso fractal desordenado. Análise das tensões de cisalhamento e efeito de escala na estimativa das forças viscosas

In this work we have investigated some aspects of the two-dimensional flow of a viscous Newtonian fluid through a disordered porous medium modeled by a random fractal system similar to the Sierpinski carpet. This fractal is formed by obstacles of various sizes, whose distribution function follows a power law. They are randomly disposed in a rectangular channel. The velocity field and other details of fluid dynamics are obtained by solving numerically of the Navier-Stokes and continuity equations at the pore level, where occurs actually the flow of fluids in porous media. The results of numerical simulations allowed us to analyze the distribution of shear stresses developed in the solid-fluid interfaces, and find algebraic relations between the viscous forces or of friction with the geometric parameters of the model, including its fractal dimension. Based on the numerical results, we proposed scaling relations involving the relevant parameters of the phenomenon, allowing quantifying the fractions of these forces with respect to size classes of obstacles. Finally, it was also possible to make inferences about the fluctuations in the form of the distribution of viscous stresses developed on the surface of obstacles.

Avaliação do controle da diagênese na qualidade de reservatório siliciclástico do cenomaniano superior da formação Açu, sudoeste da bacia potiguar

The distribution of diagenetic alterations in Late Cenomanian siliciclastic reservoirs from Potiguar Basin was influenced by the stratigraphic framework and the depositional system. Seismic sections and geophysical logs of two wells drilled in the SW portion of the mentioned basin above register regional stratigraphic surfaces representing maximum floods related to a transgressive event. The sequential analysis of 80 m of drill core (~450 m deep) recognized nine depositional facies with an upwards granodecrescent standard piling that limits cycles with an erosional conglomeratic base (lag) overlain by intercalations of medium to very fine sandstones showing cross bedding (channel, planar and low angled) and horizontal bedding (plane-parallel , wave and flaser). The top of the cycles is marked by the deposition of pelites and the development of paleosoils and lagoons. The correlation of genetically related facies reveals associations of channel fillings, crevasse, and flood plains deposited in a transgressive system. Detailed descriptions of seventy nine thin sections aided by MEV-EBSD/EDS, DRX and stable isotope analyses in sandstones revealed an arcosian composition and complex textural arrays with abundant smectite fringes continuously covering primary components, mechanically infiltrated cuticles and moldic and intragrain pores. K-feldspar epitaxial overgrowth covers microcline and orthoclase grains before any other phase. Abundant pseudomatrix due to the compactation of mud intraclasts concentrate along the stratification planes, locally replaced by macrocristalline calcite and microcrystalline and framboidal pyrite. Kaolinite (booklets and vermicular), microcrystalline smectite, microcrystalline titanium minerals and pyrite replace the primary components. The intergrain porosity prevails over the moldic, intragrain and contraction porosities. The pores are poorly connected due to the presence of intergranular smectite, k-feldspar overgrowth, infiltrated mud and pseudomatrix. The sandstones were subjected to eodiagenetic conditions next to the surface and shallow burial mesodiagenetic conditions. The diagenetic alterations reduced the porosity and the permeability mainly due to the precipitation of smectite fringes, compactation of mud intraclasts onto the pseudomatrix and cementing by poikilotopic calcite characterizing different reservoir petrofacies. These diagenetic products acted as barriers and detours to the flow of fluids thus reducing the quality of the reservoir.

Estudo do tratamento sequencial (adsorção e eletro-oxidação) para remediação de efluente sintético contaminado com BTX

This paper proposed the study of the treatment of a synthetic wastewater contaminated with BTX by electro-oxidation batch with the anode of Ti/PbO2, and the adsorption of BTX using expanded perlite as adsorbent material, and to evaluate the best operating conditions both methods in order to perform a sequential treatment (adsorption and electro-oxidation) and achieve greater efficiency in the removal of the compounds. The operating conditions were measured: temperature, current density and applied amount of the adsorbent material, by UV-VIS analysis and Demand Chemical oxygen demand (COD). According to the experimental results, the electro-oxidative treatment was efficient in the degradation of the compounds BTX (benzene, toluene and xylenes) in synthetic sewage due to the electrochemical properties of the anode of Ti/PbO2. The applied current density and temperature promoted increased efficiency of COD removal, reaching obtain percentages greater than 70%. In the adsorption process, the temperature increase was not a factor in the removal of organic matter, while the increase in the amount of adsorbent material led to an increase in the percentage removal, obtaining 66.30% using 2 g of adsorbent. The selected operating conditions of both treatments performed separately take into account the removal efficiency of organic matter, and the low energy consumption and operating costs, so the sequential treatment were satisfactory reaching 87.26% of COD removal using adsorption as a pretreatment. Quantification of BTX through the analysis of gas chromatography at the end of the treatments also confirmed the removal efficiency of organic compounds, giving outstanding advantages to sequential treatment.

Petrologia das fraturas associadas a feições típicas de dissolução hipogênica na Formação Salitre, Bacia de Irecê, Bahia, Brasil

The recognition of karst reservoirs in carbonate rocks has become increasingly common. However, most karst features are small to be recognized in seismic sections or larger than expected to be investigated with borehole data. One way forward has been the study of analogue outcrops and caves. The present study investigates lithofacies and karst processes, which lead to the generation of the largest system of caves in South America. The study area is located in the Neoproterozoic Una Group in central-eastern Brazil. This province comprises several systems of carbonate caves (Karmann and Sanchéz, 1979), which include the Toca da Boa Vista and Barriguda caves, considered the largest caves in South America (Auler and Smart, 2003). These caves were formed mainly in dolomites of the Salitre Formation, which was deposited in a shallow marine environment in an epicontinental sea (Medeiros and Pereira, 1994). The Salitre Formation in the cave area comprises laminated mud/wakestones, intraclastic grainstones, oncolitic grainstones, oolitic grainstones, microbial laminites, colunar stromatolites, trombolites and fine siliciclastic rocks (marls, shales, and siltites). A thin layer and chert nodules also occur at the top of the carbonate unit. Phosphate deposits are also found. Our preliminary data indicate that folds and associated joints control the main karstification event at the end of the Brasiliano orogeny (740-540 Ma). We recognized five lithofacies in the cave system: (1) Bottom layers of grainstone with cross bedding comprise the main unit affected by speleogenesis, (2) thin grainstone layers with thin siltite layers, (3) microbial laminites layers, (4) layers of columnar stromatolites, and a (5) top layer of siltite. Levels (1) to (3) are affected by intense fracturing, whereas levels (4) and (5) seal the caves and have little fracturing. Chert, calcite and gipsite veins cut across the carbonate units and play a major role in diagenesis. Our preliminary study indicate that hypogenic spelogenesis is the main process of karst development and contributed significantly to the generation of secondary porosity and permeability in the carbonate units.

Estudo de métodos de tratamento de efluentes (troca iônica e eletroquímico) separados e sequenciais para eliminação de derivados de petróleo

The produce of waste and the amount of the water produced coming from activities of petroleum production and extraction has been a biggest challenge for oil companies with respect to environmental compliance due to toxicity. The discard or the reuse this effluent containing organic compounds as BTEX (benzene, toluene, ethylbenzene and xylene) can cause serious environmental and human health problems. Thus, the objective this paper was study the performance of two process (separately and sequential) in one synthetic effluent for the benzene, toluene and xylene removal (volatile hydrocarbons presents in the produced water) through of electrochemical treatment using Ti/Pt electrode and exchange resin ionic used in the adsorption process. The synthetic solution of BTX was prepared with concentration of 22,8 mg L-1, 9,7 mg L-1 e 9,0 mg L-1, respectively, in Na2SO4 0,1 mol L-1. The experiments was developed in batch with 0.3 L of solution at 25ºC. The electrochemical oxidation process was accomplished with a Ti/Pt electrode with different current density (J = 10, 20 e 30 mA.cm-2). In the adsorption process, we used an ionic exchange resin (Purolite MB 478), using different amounts of mass (2,5, 5 and 10 g). To verify the process of technics in the sequential treatment, was fixed the current density at 10 mA cm-2 and the resin weight was 2.5 g. Analysis of UV-VIS spectrophotometry, chemical oxygen demand (COD) and gas chromatography with selective photoionization detector (PID) and flame ionization (FID), confirmed the high efficiency in the removal of organic compounds after treatment. It was found that the electrochemical process (separate and sequential) is more efficient than absorption, reaching values of COD removal exceeding 70%, confirmed by the study of the cyclic voltammetry and polarization curves. While the adsorption (separately), the COD removal did not exceed 25,8%, due to interactions resin. However, the sequential process (electrochemical oxidation and adsorption) proved to be a suitable alternative, efficient and cost-effectiveness for the treatment of effluents petrochemical.

Estudo de simulação de reservatórios para o desenvolvimento de um campo do nordeste brasileiro

In the last 16 years emerged in Brazil a segment of independent producers with focus on onshore basins and shallow waters. Among the challenges of these companies is the development of fields with projects with a low net present value (NPV). The objective of this work was to study the technical-economical best option to develop an oil field in the Brazilian Northeast using reservoir simulation. Real geology, reservoir and production data was used to build the geological and simulation model. Due to not having PVT analysis, distillation method test data known as the true boiling points (TBP) were used to create a fluids model generating the PVT data. After execution of the history match, four development scenarios were simulated: the extrapolation of production without new investments, the conversion of a producing well for immiscible gas injection, the drilling of a vertical well and the drilling of a horizontal well. As a result, from the financial point of view, the gas injection is the alternative with lower added value, but it may be viable if there are environmental or regulatory restrictions to flaring or venting the produced gas into the atmosphere from this field or neighboring accumulations. The recovery factor achieved with the drilling of vertical and horizontal wells is similar, but the horizontal well is a project of production acceleration; therefore, the present incremental cumulative production with a minimum rate of company's attractiveness is higher. Depending on the crude oil Brent price and the drilling cost, this option can be technically and financially viable.

Modelagem matemática e experimental da perda de injetividade em poços canhoneados

Water injection in oil reservoirs is a recovery technique widely used for oil recovery. However, the injected water contains suspended particles that can be trapped, causing formation damage and injectivity decline. In such cases, it is necessary to stimulate the damaged formation looking forward to restore the injectivity of the injection wells. Injectivity decline causes a major negative impact to the economy of oil production, which is why, it is important to foresee the injectivity behavior for a good waterflooding management project. Mathematical models for injectivity losses allow studying the effect of the injected water quality, also the well and formation characteristics. Therefore, a mathematical model of injectivity losses for perforated injection wells was developed. The scientific novelty of this work relates to the modeling and prediction of injectivity decline in perforated injection wells, considering deep filtration and the formation of external cake in spheroidal perforations. The classic modeling for deep filtration was rewritten using spheroidal coordinates. The solution to the concentration of suspended particles was obtained analytically and the concentration of the retained particles, which cause formation damage, was solved numerically. The acquisition of the solution to impedance assumed a constant injection rate and the modified Darcy´s Law, defined as being the inverse of the normalized injectivity by the inverse of the initial injectivity. Finally, classic linear flow injectivity tests were performed within Berea sandstone samples, and within perforated samples. The parameters of the model, filtration and formation damage coefficients, obtained from the data, were used to verify the proposed modeling. The simulations showed a good fit to the experimental data, it was observed that the ratio between the particle size and pore has a large influence on the behavior of injectivity decline.

Estudo e aplicação da transformada de Fourier na regularização de dados sísmicos na exploração de petróleo

In the oil prospection research seismic data are usually irregular and sparsely sampled along the spatial coordinates due to obstacles in placement of geophones. Fourier methods provide a way to make the regularization of seismic data which are efficient if the input data is sampled on a regular grid. However, when these methods are applied to a set of irregularly sampled data, the orthogonality among the Fourier components is broken and the energy of a Fourier component may "leak" to other components, a phenomenon called "spectral leakage". The objective of this research is to study the spectral representation of irregularly sampled data method. In particular, it will be presented the basic structure of representation of the NDFT (nonuniform discrete Fourier transform), study their properties and demonstrate its potential in the processing of the seismic signal. In this way we study the FFT (fast Fourier transform) and the NFFT (nonuniform fast Fourier transform) which rapidly calculate the DFT (discrete Fourier transform) and NDFT. We compare the recovery of the signal using the FFT, DFT and NFFT. We approach the interpolation of seismic trace using the ALFT (antileakage Fourier transform) to overcome the problem of spectral leakage caused by uneven sampling. Applications to synthetic and real data showed that ALFT method works well on complex geology seismic data and suffers little with irregular spatial sampling of the data and edge effects, in addition it is robust and stable with noisy data. However, it is not as efficient as the FFT and its reconstruction is not as good in the case of irregular filling with large holes in the acquisition.

Estudo e aplicação da transformada de Fourier na regularização de dados sísmicos na exploração de petróleo

In the oil prospection research seismic data are usually irregular and sparsely sampled along the spatial coordinates due to obstacles in placement of geophones. Fourier methods provide a way to make the regularization of seismic data which are efficient if the input data is sampled on a regular grid. However, when these methods are applied to a set of irregularly sampled data, the orthogonality among the Fourier components is broken and the energy of a Fourier component may "leak" to other components, a phenomenon called "spectral leakage". The objective of this research is to study the spectral representation of irregularly sampled data method. In particular, it will be presented the basic structure of representation of the NDFT (nonuniform discrete Fourier transform), study their properties and demonstrate its potential in the processing of the seismic signal. In this way we study the FFT (fast Fourier transform) and the NFFT (nonuniform fast Fourier transform) which rapidly calculate the DFT (discrete Fourier transform) and NDFT. We compare the recovery of the signal using the FFT, DFT and NFFT. We approach the interpolation of seismic trace using the ALFT (antileakage Fourier transform) to overcome the problem of spectral leakage caused by uneven sampling. Applications to synthetic and real data showed that ALFT method works well on complex geology seismic data and suffers little with irregular spatial sampling of the data and edge effects, in addition it is robust and stable with noisy data. However, it is not as efficient as the FFT and its reconstruction is not as good in the case of irregular filling with large holes in the acquisition.

Análise comparativa de diferentes configurações de poços no processo de combustão in-situ

With an increasing number of mature fields, heavy oil recovery has performed one of the great challenges of the oil industry. The Brazilian Northeast, for example, has numerous heavy oil reservoirs are explored with the use of thermal methods. Among the types of methods used for heavy oil, there is the method of in-situ combustion, a technique in which heat is produced within the container, unlike the injection of heated fluid when the heat is generated at the surface and transported to the reservoir. In this type of process, it is common to use vertical wells as injectors and producers. However, methods which use horizontal wells like oil producers are increasingly studied because of greater contact area between the formation and combustion front. Thus, the main objective of this work was to study the different configurations of wells (CIS THAITM and CAGD) in the process of in-situ combustion in oil recovery using a semi-synthetic tank with Brazilian Northeast features. The method "toe-to-heel air injection" (THAITM) is a process of enhanced oil recovery, which is the integration of in-situ combustion with technological advances in drilling horizontal wells. This method uses horizontal wells such as oil producers, keeping vertical injection wells for injecting air. The oil drain process by differential gravitational assisted with combustion (CAGD) is an integrated, in this configuration the horizontal injector well is drilled at the top formation with a horizontal production well in the lower section. The simulations were performed in a commercial program of thermal processes, called "STARS" (Steam, Thermal, and Advanced Processes Reservoir Simulator), the company CMG (Computer Modelling Group). An analysis of the air flow injection was performed and it was found that each method had a maximum injection to the base model, a show that through this air injection limit was reduced cumulative production of oil. Analyses of operating parameters were used: injection flow, configuration and completion of wells. In the sensitivity analysis we found that the air injection flow showed greater influence on THAI method, since the CIS method the completion of the wells was the most influential parameter and CAGD configuration wells showed the greatest influence in the recovered fraction. The economic results have shown that the best case obtained in CAGD method because, despite having higher initial cost showed the best financial return compared to the best cases the CIS and THAI.

Análise comparativa de diferentes configurações de poços no processo de combustão in-situ

With an increasing number of mature fields, heavy oil recovery has performed one of the great challenges of the oil industry. The Brazilian Northeast, for example, has numerous heavy oil reservoirs are explored with the use of thermal methods. Among the types of methods used for heavy oil, there is the method of in-situ combustion, a technique in which heat is produced within the container, unlike the injection of heated fluid when the heat is generated at the surface and transported to the reservoir. In this type of process, it is common to use vertical wells as injectors and producers. However, methods which use horizontal wells like oil producers are increasingly studied because of greater contact area between the formation and combustion front. Thus, the main objective of this work was to study the different configurations of wells (CIS THAITM and CAGD) in the process of in-situ combustion in oil recovery using a semi-synthetic tank with Brazilian Northeast features. The method "toe-to-heel air injection" (THAITM) is a process of enhanced oil recovery, which is the integration of in-situ combustion with technological advances in drilling horizontal wells. This method uses horizontal wells such as oil producers, keeping vertical injection wells for injecting air. The oil drain process by differential gravitational assisted with combustion (CAGD) is an integrated, in this configuration the horizontal injector well is drilled at the top formation with a horizontal production well in the lower section. The simulations were performed in a commercial program of thermal processes, called "STARS" (Steam, Thermal, and Advanced Processes Reservoir Simulator), the company CMG (Computer Modelling Group). An analysis of the air flow injection was performed and it was found that each method had a maximum injection to the base model, a show that through this air injection limit was reduced cumulative production of oil. Analyses of operating parameters were used: injection flow, configuration and completion of wells. In the sensitivity analysis we found that the air injection flow showed greater influence on THAI method, since the CIS method the completion of the wells was the most influential parameter and CAGD configuration wells showed the greatest influence in the recovered fraction. The economic results have shown that the best case obtained in CAGD method because, despite having higher initial cost showed the best financial return compared to the best cases the CIS and THAI.