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AbstractStoring carbon dioxide in depleted petroleum reservoirs is a viable strategy for carbon mitigation, but ensuring that the sequestered CO2 remains in the formation is vital to the success of such projects. There is great concern for the development of leakage pathways through annuli between the well cement and the formation or the casing. Predicting the behavior of such potential leakage pathways is critical. Numerical simulations conducted using a reactive transport module match well with experimental studies, but also show the necessity of quantifying the transport and mechanical properties of the leached solid cementitious solids–predominantly silica gel–produced by carbonic acid corrosion of well cement.Bench-top experiments have been performed with the following goals in mind: (1) to investigate the parameter space of relevant corrosion boundary conditions, e.g. pH, CO2 concentration, and calcium ion concentration, (2) to produce samples that can be used to quantify the transport and mechanical properties of acid corroded Class H well cement, and (3) to validate and improve the accuracy of numerical simulations of the reaction of well cement with carbonic acid.Class H cement samples were uniaxially corroded via exposure to a brine of constant composition. Constant composition is ensured by constant renewal of the brine at a rate larger than cement reaction rate. H+, Ca2+ and CO2 total aqueous concentration in the NaCl brine are controlled independently by adding known amounts of NaCl, HCl, CaCl2 and NaHCO3 and by controlling CO2 partial pressure. Microscopic (30X) time-lapse videos were taken of each sample so that corrosion front movements could be accurately measured. These experiments have yielded corrosion front measurements that clearly show that corrosion front advancement is diffusion controlled (i.e., linear as a function of the square root of time). The uniaxial corrosion of these samples has not only allowed for detailed measurements of the corrosion front, but also affords the opportunity to measure the mechanical properties of the corroded samples as a function of depth. The one-dimensional corrosion also allows for measuring the diffusion coefficient of the outer layer of silica gel by low field Nuclear Magnetic Resonance (NMR).Measuring the kinetics under various boundary conditions has validated the modeling results reported by Huet et al.. The measurements of mechanical and transport properties can now be used to improve the predictive power of these simulations by providing much needed information on the exterior layer of corroded Class H well cement. Additionally, these experiments offer experimental validation that the corrosion kinetics are enhanced by the presence of CO2 and open the door to better understanding of the mechanism of, and boundary conditions that might lead to, “pore-plugging” by the corrosion products, which in turn leads to a drastic retardation of the corrosion reaction.

AbstractAmine degradation and corrosion can be a severe operational problem in the CO2 absorption process. In this paper the effect of MEA's degradation products on corrosion is studied. Different solutions of MEA 30wt% containing also 1wt% of a specific degradation product were placed in 316 stainless steel cylinders and stored in a thermostat chamber at 135oC. Samples are analysed for Fe, Cr, Ni and Mo by ICP-MS as an indication of corrosivity. The results showed that after 5 weeks loaded MEA 30wt% with 1wt% oxalic acid was the most corrosive solution.

AbstractGas tracers have been tested for monitoring and detecting CO2 displacement in the underground and eventually leakages to the upper layers in geological storage sites. Commonly used tracers are perfluorocarbons (PFCs) and sulfur hexafluoride (SF6). In Brazil, we are carrying out gas tracers studies in laboratory for further application in field test facilities. These experiments consist of injecting CO2 with perfluorocarbon (perfluoropropane – PP and perfluormethylcyclopentane – PMCP) at low pressure (ca. 290 psi) in pressurized vessels with different types of sediments and soil samples. After flowing through the sample pores, the tracer is adsorbed into a capillary adsorption tube (CAT) with a specific fiber for perfluorcabon. Then, the tracer is extracted from the CAT through a Thermal Desorption System and subsequently analyzed in a Gas Chromatograph with an Electron Capture Detector (GC -ECD). The objective of these experiments is to evaluate the PFCs as a monitoring tool, analyzing the tracer retention times in different sediments, as well as understanding the CATs adsorption capacity and performance. After laboratory tests, field experiments will be conducted in the course of this project. Several experiments of CO2 injection and controlled leaks will be developed in shallow vertical wells at the project site as a continuity of the experiments started at Ressacada Farm Site (Florianópolis, Brazil). The project aim is to understand the flow and dispersion of CO2 in soil and atmosphere simulating an eventual leakage from a geological reservoir using an automated system with a dedicated module for tracers injection into CO2 stream.

AbstractIn this paper three-dimensional mathematical model of gas-solid two-phase in a radial style diesel particulate filter (DPF) is established and flow computation software was used to simulating distribution characteristics of gas-solid two-phase and particle distribution uniformity. Several influence parameters such as flow velocity, divergence angle and particle diameter was investigated. Through the verification analysis, the simulation calculation results can reflect the laws of gas-solid two-phase flow inside this DPF .The results indicate that distribution uniformity of particle could be improved by reducing inlet velocity, divergence angle and particle diameter. The study is useful for structural parameters optimization designing and controlling particle regeneration of radial style diesel particulate filter.

Abstract The laminar burning velocity is a fundamental property of a reactive fuel-oxidizer mixture, varying with composition, pressure and initial temperature. These values are important for validation of reaction mechanisms and the specific design of industrial burners. There are several experimental methods to measure laminar burning velocity, e.g. the bunsen flame method, the spherically expanding flame method, the stagnation flame method and the flat flame burner method, which also includes the heat-flux burner method. The accuracy of the different methods could be enhanced over the last years but there are still uncertainties of up to 30 % depending on method, boundary condition and fuel composition. Furthermore, for a lot of fuels, especially fuel blends, there is a lack of data. In this study, the heat-flux burner method was applied to measure laminar burning velocities of low calorific fuels and hydrogen containing fuel blends. These fuel blends are of major interest since the hydrogen concentration in the gas grid system could in future to a significant value. For example, within the “power-to-gas” concept, some new technologies arise to use renewable energy to produce hydrogen and take it as “fuel”. On the other hand, the change of the gas composition also changes the combustion properties, for example burning velocity, heating value and ignition delay. Therefore, different low calorific fuels and hydrogen containing fuel are tested within a range of equivalence ratios from 0.7 to 1.4 for initial temperatures of 298 K up to 363 K for atmospheric conditions.

Abstract This paper reports findings from a preliminary study into the stacking characteristics of asphaltenes extracted from an oil sand and two petroleum vacuum residues. The stacking morphology was examined using high resolution transmission electron microscopy (HRTEM). The stacking parameters of the three samples including the average stacking number, the average interlayer spacing and the average layer size were estimated. The results showed that the asphaltenes extracted from the petroleum vacuum residues possessed higher stacking numbers with smaller interlayer spacing as compared to the asphaltene from the oil sand. This indicates that the intermolecular forces of the petroleum vacuum residue asphaltenes are stronger than that of the oil sand. The average layer size across the samples is ca. 0.9 nm, implying the average PAH size of 6∼7 fused rings for all samples.

Abstract Explosion characteristics of syngas/air mixtures was investigated numerically in a 3-D cylindrical geometric model, using ANSYS Fluent. The results showed that the maximum explosion pressure increased from lean to an equivalence ratio of 1.2, then decreased significantly with richer mixtures, indicating that maximum explosion pressure occurred at the equivalence ratio of 1.2, while explosion time was shortest at an equivalence ratio of 1.6. Increasing H2 content in the fuel blends raised maximum explosion pressure and significantly shortened the explosion time. Normalized peak pressure was sensitive to the initial pressure of the mixture, showing that they significantly changed with increased initial pressure.