Applied Mechanics and Materials Vol. 830

Abstract: Petroleum production always comes accompanied by some contaminants, including CO₂. Recent pre-salt exploration in Brazil indicates significant carbon dioxide (CO₂) concentration levels. Whereas in post-salt areas a ratio of 1 to 2% in CO₂ concentration was observed, in the pre-salt area this molar ratio increased to 15 to 20% in relation to the gas phase, and were even higher in some cases. Several challenges have emerged in the production, treatment and disposal of oil with such high levels of CO₂. The aim of this study is to show the management of CO₂ in a pre-salt producing platform whose CO₂ content is about 18% molar in the gas phase. The focus is on the operational aspects of daily production, where theoretical analyses are compared with the data observed in the field. Scenarios of production, injection, treatment and export are presented with emphasis on the aspects of flow assurance, the characterization of fluids, the integration of the injection-production-export system, and the dilution of CO₂.

Abstract: The exploration of pre-salt introduces challenges beyond those posed by ultra-deep waters and the thick of carbonaceous reservoirs. Among the main difficulties are the high gas-oil ratio and the high content of carbon dioxide (CO₂) present in the gas. This paper proposes an alternative to the technology currently used in the exploration of pre-salt, in which the gas is treated on the platform. The proposed alternative is applicable to reservoirs which CO₂ concentration in gas is greater than 50%, like Jupiter that contains 79% of CO₂. For this scenario is suggested that exploration occurs in three production areas: subsea, offshore and onshore. The proposed technology includes the construction of three subsea pipelines: one for the transportation of untreated gas (that is treated onshore); a second for the return of the recovered hydrate inhibitor (in order to be re-injected into the gas pipe) and the last for the return of the carbon dioxide stream separated from the gas.

Abstract: Thermoeconomics is a discipline that connects Thermodynamics and Economics concepts, usually used for rational cost assessment of the final products of a thermal plant, by means of a model which describes the cost formation process of the overall system. Generally, exergy or monetary costs of the external resources are distributed to the final products. However, environmental consideration can be incorporated in the models to calculate the environmental costs, such as specific CO₂ emission of each final product. This work aims at demonstrating how the thermoeconomic models can be adapted or modified in order to allocate the overall CO₂ emission of a gas turbine cogeneration system to the final products (net power and useful heat), in order to determine the specific CO₂ emission (g/kWh) of each product. This subject is an important step in the applications of Life Cycle Assessment in plants with two or more products and also to quantify the environmental cogeneration advantage. It also reveals that any thermoeconomic model can be adapted for allocation of the overall CO₂ emissions or any other pollutant to the final products of a multi-product plant.

Abstract: The recent discoveries of Pre-Salt layers in Brazil require process developments for enhanced sustainability as these reservoirs have oil with associated natural gas exhibiting an expressive amount of CO₂ [1,2]. The challenge is thus to expand the supply of this fossil raw material to produce energy and chemicals in a carbon-constrained economy. In this scenario, CO₂ capture and reuse techniques are important routes for a moderate transition from the present fossil-based economy to a long-term sustainable future. This work evaluates two process alternatives for a floating unit consisting of physical absorption of CO₂ from natural gas, with propylene carbonate, producing a natural gas stream poor in CO₂ and a stream consisting of a mixture of CO₂ and hydrocarbons. Two alternatives are evaluated for processing the CO₂ rich stream to yield methanol. Technical, economic and environmental analyses of the process flowsheets are performed for comparison purposes. Alternative 1 combines dry and steam reforming in one reactor (one pot reactor, Bi-Reforming), while Alternative 2 segregates the two reactions: dry reforming (Dry-Reforming) occurs in one reactor and water gas-shift reaction takes place in a subsequent reactor. The two Alternatives are evaluated with ASPEN HYSYS® (ASPENTECH Inc) simulator for calculation of energy and mass balances necessary to assess economic and environment performances. The economic evaluation employed the software Capital Cost Estimation (CAPCOST) for calculations of CAPEX and OPEX. The software Waste Reduction Algorithm (WAR, EPA) was used to evaluate the potential environmental impacts, by PEI (Potential Environmental Impact). Results indicate that the performance of Alternative 1 was better than Alternative 2: (a) methanol production (17905 kg/h) 4 times higher, (b) CAPEX (U$$75.497.127), 21,7% lower, (c) Sales Revenue (U$$144,890,686) 181% greater, and (d) the index for environment impact (868 PEI/hr) 47,7% lower.

Abstract: With the demand for Biofuels growing – worldwide – and with the efforts to reduce greenhouse gas emissions (GHG), much would be gained, from an environmentally and economically, from increasing efficiency and offer of biofuels. Biofuels produced in algae farms enable a close relationship with ethanol plants. Such algae feeds off Carbon Dioxide from biomass burned in ethanol plants and boilers, so, along with Brazil’s privileged solar incidence, this allows conversion of GHG to biofuel. The goal of our study was to investigate ethanol plants as productive systems to understand how adding algae farms could change energy efficiency and emissions. The system analyzed includes the sugarcane sowing, plantation, handling, harvesting, industrial activities, and ethanol distribution. Our aim, from this analysis and using primary data from a company that builds algae farms, is to estimate the output of algae biofuel and decrease of GHG emissions in the process. The results from the Plant Studied show that adding an algae farm to its grounds would improve energy efficiency by almost three times, while generating four times less GHG in the production chain. If the plant chose to produce exclusively Biodiesel, production of B100 Biodiesel would be enough for their diesel needs for 19 years, with a 78.4% cleaner fuel in terms of GHG. Approximations show that if all the cane mills add algae farms in Brazil, Biodiesel generation would be equivalent to almost 70% of the Brazilian production of diesel from 2012.

Abstract: The intent of this paper is to offer a comprehensive understanding of the pitfalls associated with CO₂-rich gas injection during enhanced oil recovery (EOR) operations. An emphasis is placed, however, on the interactions between this gas and crude oil asphaltenes, because these later compounds are heavy organic molecules which can destabilize, flocculate and precipitate in CO₂-rich environments, thus triggering a major field problem: injectivity loss due to near-wellbore (inflow) formation damage: an Achilles heel for any EOR process.

Abstract: Monoethylene glycol (MEG) is being widely applied as thermodynamic inhibitor to avoid formation of natural gas hydrates. High hydrophilicity, low toxicity, low viscosity, low solubility in liquid hydrocarbons and high capacity of dissolving salts are advantageous for the use of MEG in the natural gas production. In addition, MEG recovery can be easily achieved considering its low volatility in relation to water, which makes the process economical and environmentally feasible. The reuse of MEG is being theme of research and phase equilibrium data for the involved species are required. In this work, a experimental procedure to synthetize iron carbonate and, afterwards, determine its solubility in aqueous mixtures of MEG in the presence of carbon dioxide atmosphere have been developed. Furthermore, a series of solubility data has been measured. This work presents a worthy contribution to the description of iron carbonate aqueous solubilities in the presence of MEG and carbon dioxide, regarding the instability of the salt to respect of oxidation. Subsequently, the knowledge of the behavior of the iron carbonate solubilities is useful for the industrial unities of production of natural gas and recovery of MEG.

Abstract: This work evaluate the protective characteristic of the CO₂ corrosion product layers formed on the surface of two types of steels, API 5L X80 used for transportation of oil and gas, and API 5CT P110 used for case tubing and pipe for oil drilling.Electrochemistry evaluations and morphological characterization of the obtained layer were performed. These steels were exposed to a brine solution containing 3% wt of NaCl, in a pressurized autoclave with 55 bar of CO₂ and total pressure of 75 bar at different temperatures (25, 50 and 75°C) and immersion times (7, 15, 21 and 30 days). The corrosion rate was determined by mass loss tests and electrochemical techniques, such as Linear Polarization Resistance and Electrochemical Impedance Spectroscopy. Characteristics of the corrosion product layer such as thickness, morphology, and chemical composition were analyzed by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-Ray diffraction (XRD). The corrosion rate decreases with the increase of the immersion time and temperature, and the lower rate of corrosion was obtained for 75°C after 30 days of immersion, for both steels