Heavy oil reservoirs are known for their low recovery factors. Additional energy consumption, special operations, and enhanced oil recovery (EOR) techniques are required for production due to high viscosities. Also, unfavorable water-oil mobility ratio is a serious problem when waterflooding (WF) is implemented, usually causing early breakthrough and higher water cut. Developing and managing a production strategy through a comprehensive decision-making procedure is also complex due to the high number of variables, uncertainties, and physical phenomena involved. Polymer flooding (PF) is an EOR method that can be applied to heavy oil reservoirs to improve field performance by producing more oil and reducing water production. This improvement is achieved through the increase in water viscosity caused by the injection of polymers, thus reducing water-oil mobility ratio, and obtaining better oil displacement efficiency. In the case of intelligent wells (IW) equipped with Inflow Control Valves (ICVs), the WF limitations can be mitigated by controlling multiple production/injection zones, increasing oil production, and maintaining the reservoir pressure. This work aims to perform a nominal production strategy optimization to develop and manage a heavy oil reservoir considering PF as a production strategy (using conventional wells only) and comparing it to waterflooding with ICVs (WF+ICV) for the same case. A complete methodology to optimize the design and control variables is applied to the strategies by using model-based reservoir simulation. The objective function (OF) is the Net Present Value (NPV), this study case is named EPIC001, which has a 13° API heavy oil reservoir that represents part of a Brazilian offshore field. We have applied a specific methodology to optimize the PF strategy for a heavy oil reservoir of a nominal case which is practical and clear in the selection and comparison of strategies for similar cases. The results found PF strategy is the more suitable for the case, obtaining an NPV that is 21% higher than WF+ICV. Injecting polymers in the earlier stages of the life cycle at lower polymer concentration rendered PF with greater oil recovery (+13%) with a better efficiency in management of water and polymers, therefore surpassing the good ICV management from WF+ICV.
Paraffin buildup, along with other production debris, poses a significant challenge to subsea production flowlines, especially in cold, deepwater environments where extended subsea tiebacks cause crude oil to lose heat to surrounding seawater (Oliveira et al., 2018; Oliveira et al., 2024) This thermal decline can drop the oil's temperature below the critical temperature of deposition (CTD), thus, leading to paraffin accumulation. A prime example of this phenomenon is the Petrobras-operated X field off the Brazilian coast, which exemplifies the complexities of deepwater crude oil production. This manuscript details a methodology used to melt and remove paraffin buildup efficiently in a restricted-access area of the X field's surface production flowline. Using a quite simple innovative in-house solution, the paraffin deposit was melted from top to bottom and successfully removed. This represents a groundbreaking achievement, as it is the first documented instance of using the combination of dry-steam and high-pressure cleaning hoses to remove paraffin blockages in a Petrobras-operated field.
The natural gas stream is produced alongside entrapped water, and there is need to remove this entrapped water to attain hydrocarbon dew point specification. This study investigates the effect of TEG (Triethylene Glycol) recirculation rate on the water content of dehydrated natural gas, focusing on optimizing the performance, energy efficiency, and cost-effectiveness of TEG-based glycol dehydrators. That increase in TEG recirculation rate yields decrease in water content of dehydrated gas until reaching a certain TEG rate. The recommended TEG-feed gas flow rate ratio is 164 gallons TEG/MMSCF. TEG purity impacts water removal efficiency, regenerator reboiler, duty, and temperature. Increase in number of absorber stagers reduces the water content of the dehydrated gas. From the optimization study, the optimal TEG flow was determined to be 71.75 BPD (barrels of oil per day) with a purity of 0.9898, achieving the desired moisture content of 6.981 lb/MMSCF. The phase envelope and hydrate formation analysis confirmed the effectiveness of the dehydration process, ensuring gas flow even at low ambient temperatures.
The reduction of drilling time due to the addition of new equipment, tools, and technologies has reduced drilling costs significantly, leading to the production of hydrocarbons at competitive costs. Observations from project engineers are at the base of conventional well planning, using information from offset wells to estimate the costs in future wells. This works uses a statistical approach to evaluate historical drilling costs of oil and gas wells to reduce the influence of personal decisions and provide the staff with more precise data-driven cost estimations. Initially, to establish a strong foundation on the drilling cost and time estimation, we review general cost analysis concepts to estimate drilling cost and drilling time using field data to show cost trends for various depths. The study of Canto do Amaro and Estreito fields cases demonstrate the benefits of this approach in the development of new drilling projects. The solution proposed supports accurate cost planning, considering that the improvement of an operational window provides a better understanding of the cost projection when compared to traditional cost estimation.
Crude oil salinity on production platforms is measured for sale typically using ASTM D3230 (conductometry) or ASTM D6470 (potentiometry). Conductivity-based measurements employ a salimeter, which has a maximum limit of 500 ppm. However, salt levels in oil from primary separation often exceed this threshold. This work aims to adapt the salimeter method, by adjusting the oil sample size, to enable measurements above 500 ppm. Laboratory tests were carried out on an offshore production platform in a Brazilian post-salt field, using heavy crude oil samples from the platform’s primary separation. Each sample was analyzed using both standard and modified tests. Statistical comparisons, including Yuen’s robust t-test with bootstrap resampling, were applied. Results show that modified test produced values statistically equivalent to the standard test, with only slight variability increases from outliers. The modified method proposed provides a practical and reliable option for addressing high-salinity scenarios where conventional equipment reach its measurement limits.
During the drilling stage of oil production, the use of drilling fluids is essential to the success of the entire operation. These fluids exert countless properties on drilling operations, but those linked to rheological properties and maintaining the hydrostatic pressure gradient inside the oil well stand out. Since drilling fluids are subject to fluid-rock interactions, contamination by salts from the geological formation can become a problem during the exploration stage of the well, and this additional salt content can impact the fluid's rheological characteristics and density. The increased content of salts in water-based drilling fluids is characterized by an increase in the fluid's electrical conductivity. However, monitoring and controlling this property are yet to be explored. To face such challenges, this study proposes the development of a multivariable fuzzy controller to oversee the properties of electrical conductivity, apparent viscosity, and density in water-based drilling fluids. The technique was evaluated using an experimental unit for preparing and monitoring drilling fluids, where servo and regulatory tests were carried out to assess the controller's capacity. Servo tests are conducted by changing the setpoint of each variable individually, while the controller should maintain the other properties at their setpoints. Regulatory tests evaluated the controller's performance in rejecting a water kick-like disturbance imposed by the sudden addition of 10 liters of water into the system and another disturbance caused by adding 0,5 kg of salt to the fluid tank. The multivariable fuzzy control strategy developed in this work proved efficient and robust in keeping the physicochemical properties of water-based drilling fluids at their setpoints, emerging as a potential preventive and corrective tool for monitoring this process.
The combination of extreme pressure and temperature conditions with elevated carbon dioxide (CO₂) levels in pre-salt reservoirs presents substantial challenges for effective resource exploitation. This study aims to evaluate temperature variation as an indicator of phase transition. To achieve this goal, high-pressure bubble point equilibrium experiments were conducted using two non-visual synthetic methods. Experiments were performed on three CO₂-containing systems: squalane, light crude oil, and condensate gas. Five CO₂ concentrations were analyzed over a temperature range of 30 to 120 °C. A temperature drop of up to 1.2 °C was observed at the onset of the first vapor bubble, indicating an endothermic phase transition. Experiments with translucent synthetic samples, where the bubble point was determined visually through a sapphire window, confirmed that the non-visual method based on temperature variation is accurate. Furthermore, the proposed temperature-based method demonstrated performance comparable to the well-established volumetric method. Therefore, temperature variation can serve as a reliable monitoring parameter for bubble point equilibrium experiments, particularly in non-translucent samples such as petroleum.
This work aims to evaluate the influence of hydrogen and oxygen increase in the minimum formula of the energy cane Saccharum spontaneum on the pyrolysis products at 450 C and 40 bar, to achieve a greater bio-oil yield. This work adopted DWSIM 6.4.9 with a stoichiometric reactor and a minimum formula for the biomass (CH1.75O0.84). The simulations considered the sub-index varying individually between 1.0-5.0 for hydrogen, and between 0.5-2.5 for oxygen, with increments of 1.0 and 0.5, increasing its molar mass between 26.44 g/mol-30.44 g/mol and 21.75 g/mol-53.75 g/mol, respectively. By varying hydrogen, liquid yields increased (51.79%-53.57%), gas yields decreased (32.20%-29.46%), and solid yields remained practically constant (26.01%-26.97%). Regarding the oxygen, gases decreased (36.66%-21.42%) and solids and liquids increased more significantly (24.61%-30.62% and 48.73%-57.96%). Finally, the oxygen increment in the biomass lowered CO and CO2 fractions (1.38-0.53 and 0.88-0.33) kg/h, respectively, and the presence of water-gas shift reaction increased CO2 fraction (0.04-0.08).
The exploration of oil and gas at great depths requires the use of drill strings composed of connections with highly resistant shoulders, designed to withstand intense and complex loads in hostile environments, where they are prone to the emergence of mechanical weaknesses. To ensure the efficiency and safety of these connections, it is essential to assess their operational limits, particularly the maximum stress they can withstand without exceeding the material’s yield strength. This study employs the Finite Element Method to analyze the stress distribution in a connection subjected to make-up torque and axial tensile load. The methodology involves the axisymmetric modeling of the NC46 connection in ABAQUS®, data processing, and the calculation of the Stress Concentration Factor. The results indicate that the highest stress concentrations occur at the root of the first engaged thread on the pin, aligning with findings from reference studies. Results also show that the preloading effect helps mitigate stress concentration under the applied load.
The intensification of climate change accelerates the need for development of technologies to reduce CO₂ and CH₄ emissions. Carbon capture and storage (CCS) enable the safe retention of CO₂ in saline aquifers, which offer high storage capacity. The present study uses a siliciclastic saline aquifer model in GEM software to simulate the injection of 30% to 100% CO2 concentrations for 30 years, assessing the impact on physical and chemical trapping mechanisms for a thousand years. Results indicated that in all scenarios, dissolution was the most significant trapping mechanism, consistently followed by structural trapping, with little influence on mineralization. The mineral activity generated the dissolution of clay minerals and feldspars, with precipitation of calcite, dolomite, kaolinite and chalcedony by mineralization. The results suggest that optimizing CO2 concentration can improve the efficiency of CCS projects in saline aquifers.
Oil sands mature fine tailings are stable suspensions of clay particles and residual bitumen that consolidate and dewater very slowly. This work selected a series of amphiphilic copolymers of acrylamide with comonomers presenting different hydrophobic chains (butyldiglycol methacrylate, 2-dimethylaminoethyl methacrylate, n-butyl methacrylate, and n-octyl methacrylate) and used them to flocculate and dewater oil sands tailings. It analyzes the influence of molecular weight, hydrodynamic volume, and hydrophobicity of these polymers on their flocculation and dewatering behavior using initial settling rate, supernatant turbidity, capillary suction time, and solid sediments content. The performance of these novel amphiphilic copolymer flocculants depended mostly on their hydrodynamic volumes and on their degree of hydrophobicity.
The present work aims to model the dynamic evolution of the “Annular Pressure Buildup” (APB) in oil wells to understand the effect of the operational parameters on this phenomenon as well as to propose an approach to model the fluid drainage to the rock formation, which is one of the possible mechanisms for annular pressure relief. To reach this goal, a detailed mathematical model of this process was developed considering design parameters such as oil well geometry, casings’ mechanical properties, rock formation’s geological characteristics, and physical-chemical factors related to the drilling fluid and its composition. The mathematical modeling of the APB phenomenon was based on the equations for the conservation of mass and energy, the equations of state for the thermodynamic properties of fluids, the mechanical properties of solid materials, and the PVT relations. Simulations were performed considering the worst scenario, i.e., the condition of complete sedimentation of solid contents of the drilling mud, aiming to verify under which conditions the fluid drainage would occur through the cake formed by the settled solids. Comparisons between different configurations of oil wells and rock formations with different geomechanical properties were also obtained for the APB calculation, considering the proposed model for pressure relief. The simulation results from the approach proposed in this work were compared to those obtained from WELLCAT™ software (Halliburton), a casing and tubing design computational package widely used for oil companies operating in heavy-oil drilling and production environments, showing deviations below 3%.
Hydrogen is crucial in the ongoing energy transition and essential for various industrial applications. Methane reforming, hydrogen evolution reaction (HER), and photocatalysis are among examples of the viable methods used in the sustainable production of hydrogen. The use of ceramic membrane reactors show great potential in industrial processes such as partial methane oxidation, as they can selectively remove hydrogen while increasing efficiency. However, the high stability of methane requires strong and effective catalysts. Nickel is a cost-effective alternative to noble metals, while tungsten is known for its excellent chemical and physical properties. In this study, we synthesize a nickel tungstate (NiWO₄) membrane for the first time using the EDTA/citrate method. The complexation step was designed to organize the metal ions properly within an organic matrix before calcination at 1000 °C for 5 or 10 hours. X-ray diffraction analysis confirmed high NiWO₄ yields — 87% after 5 hours and 89% after 10 hours — with corresponding crystallite sizes of 96.78 nm and 95.14 nm, respectively. Morphological characterization validated the presence of a monoclinic structure and indicated heterogeneity in crystal size, consistent with existing literature. This NiWO₄ synthesis method demonstrates high potential for the fabrication of advanced ceramic materials aimed at hydrogen production processes.
The present study conducts a comparative analysis between two computational simulation softwares, OpenFOAM and MAXSURF, applied to the design of small vessels developed for use in the Amazon region. The analysis considered a vessel with a hull draft of 0.1m and speed variations of 5 and 10 knots. Both softwares were used to study the waves generated by a vessel, a characteristic that directly impacts navigation safety, assisting in the prevention of riverbank erosion and reducing the risk of accidents. OpenFOAM, a software based on the Finite Volume Method, was used to analyze fluid behavior by simulating interactions between air, water, and the vessel. In MAXSURF, simulations were conducted to analyze hull shape, wave studies, accurate estimation of resistance to motion at different speed regimes, and even the power required for the engine. The results obtained highlight the potential of both hydrodynamic analysis tools.
Bio-oil obtained from biomass pyrolysis has emerged as an interesting alternative to replace fossil fuels. The aim of this study is to evaluate the influence of temperature (350 – 520 °C) on the yield of products from the pyrolysis of powder obtained from dry branches of Euphorbia tirucalli, using a laboratory-scale rotating cylinder reactor. The biomass was treated and characterized to estimate CHNS contents, moisture, volatile materials, ash and carbon, lignin, cellulose and hemicellulose contents, FTIR, TG/DTG, XRD, XRF and SEM. The activation energy for biomass degradation was evaluated in the non-isothermal regime with heating rates of 5 and 10 °C/min, which had values between 232.92 and 392.84 kJ/mol. The results obtained showed biomass as a raw material with potential for biofuel production, as it had a high content of organic matter (78.3%) and fixed carbon (7.11%). The maximum bio-oil yield was obtained at a temperature of 450°C, with the following results: bio-oil content of 8.12%; char of 32.7%; non-condensed gas phase of 35.4%; losses of 23.8%; higher heating value of 3.43 MJ/kg; pH of 4.93; viscosity of 1.5 cP. The chromatographic analysis of the bio-oil produced under these conditions showed the presence of phenol (17.71%), methylcyclopentenone (10.56%) and dimethylcyclopentenone (7.76%).
Brazilian offshore production fields are maturing, requiring decommissioning structures and equipment, such as platforms and subsea pipelines, therefore, presenting challenges to its oil and gas industry. These projects demand substantial financial resources and technological innovations due to the limited national experience in this arena. This article proposes a multicriteria decision support model to assist managers in selecting the best alternatives for decommissioning subsea systems. The qualitative methodology includes a literature review and an analysis of public data from the National Petroleum Agency (ANP) and Petrobras. The SMARTER technique was adopted for being suitable for the current scenario, characterized by scarce data and limited historical experience. Results indicate that the model is widely applicable, contributing to the support of effective decisions in decommissioning, whether through hourly-paid contracts or lump-sum agreements, in the EPRD format (Engineering, Preparation, Removal, and Final Disposal).
Petrophysical characterization is essential for evaluating reservoir properties. Large hydrocarbon discoveries in pre-salt coquinas have motivated research on more accessible analogues, such as the coquinas of the Morro do Chaves Formation at the Sergipe- Alagoas (SE-AL) Basin. This study employs geophysical inversion methods to predict petrophysical parameters using well logs and laboratory data from well 2-SMC-AL. The objective was to estimate a continuous porosity profile correlated with the porosity measured in the laboratory. For this purpose, the observed density was adjusted to the total density of the samples and, via Markov Chain Monte Carlo (MCMC), the coefficients of the Gardner equation (1974) – a, b, c – were determined, allowing the generation of a continuous density profile (ρGardnerFIT) and, subsequently, a porosity profile (PhiEDENFIT). As an alternative method, the Raymer (1980) and Wyllie (1956) equations were used to estimate porosity from the sonic log. The best fit was obtained by PhiEDENFIT, demonstrating the effectiveness of the MCMC method combined with the Gardner equation in predicting petrophysical properties in complex carbonate reservoirs.
The oil and gas industry faces significant challenges in managing produced water, which is generated in large volumes, at a ratio of 1:3 to oil production, potentially increasing to 1:12 over time. Produced water contains complex constituents, including naphthenic acids, which are resistant to degradation and cause corrosion in equipment. Conventional technologies for treating produced water have limitations, therefore, the industry demands the development of more efficient methods for removing these acids from the water. This study evaluates the UVC/H2O2 advanced oxidative method for treating produced water. Synthetic produced water containing cyclohexane carboxylic and cyclohexane acetic acids was treated under ambient conditions with H2O2 concentrations of 150 mg/L. The results show that the UVC/H2O2 method achieved removal efficiencies of up to 40.32% for cyclohexane carboxylic acid and 52.54% for cyclohexane acetic acid, with higher removal rates at lower acid concentrations. The findings demonstrate the potential of this method in degrading these acids, providing insights into reaction kinetics and optimization of produced water treatment.
The key to a successful and economically viable drilling operation lies in optimum drilling aimed at completing drilling activity within the shortest possible period with the least damage to equipment, formation, and environment. However, the increase in complexity requirements for drilling activities has led to several problems such as poor rate of penetration (ROP), which results in an increase in non-productive time (NPT) and in additional associated costs. In this study, Random Forest (RF) from scikit-learn package and Linear Regression (LR) from XlStat software were utilized for machine learning evaluation for ROP prediction. A 150 dataset from a Niger-Delta oilfield was utilized to develop a model which was statistically evaluated and validated, featuring important parameters detected. Study results show the RF regression model recorded R2 of 99.12%, MSE of 9.38%, RMSE of 3.06% and MAE of 1.8%, while LR yielded R2, MSE, MAE and RMSE of 77.5%, 25.42%, 2.56%, and 5.2% respectively. Validation results present RF recorded values closer to the actual ROP in comparison to the ones found using the Linear Regression (LR) model. From the results, feature importance study, plastic viscosity, rotary speed, and standpipe pressure had the highest impact on ROP.
Biofuel production, particularly bio-jet fuel, has been incentivized due to the potential environmental benefits it can create. However, its production often relies on hydrogen from fossil sources, diminishing its sustainability. This work proposes a more sustainable alternative to the production of bio-jet fuel which involves generating hydrogen through the oxidation of metallic zinc in water, a safer and cleaner process. In this context, the study simulates bio-jet fuel production using non-fossil hydrogen from zinc oxidation. The process, modeled with Aspen Plus® V10, combines fatty acids and hydrogen to produce biokerosene, alongside zinc oxide, a commercially valuable byproduct. The proposed method operates under mild conditions (220 °C, 24 bar), reducing refinery dependence and offering economic advantages. The system was found to be economically viable with a 6-year investment payback and low CO2 emissions (4 kg CO2eq/kg H2), comparable to blue or turquoise hydrogen. Overall, this approach presents a sustainable and economically viable alternative for bio-jet fuel production, reducing the reliance on fossil sources and promoting greener aviation fuel.
