A dual-porosity dual-permeability model for acid gas injection process evaluation in hydrogen-carbonate reservoirs

The Pre-Caspian basin is one of the most prolific in terms of oil and gas exploration and hydrogen and carbon compounds energy production around the world. The major hydrogen and carbon compounds reservoirs are Carboniferous reef and platform hydrogen-carbonate rocks. The original fluids under subsurface conditions contain 15% hydrogen sulfide and 4% carbon dioxide. Acid hydrogen and carbon compounds reinjection is not only an environmentally friendly solution for disposal of produced greenhouse gases but also enhances oil recovery and supplies more fuel energy. On the other hand, the presence of fractures makes hydrogen-carbonate reservoir characteristics nature more complicated than conventional sandstone reservoirs, which leads to a tremendous challenge to evaluate the gas injection process. In this work, a dual-porosity dual-permeability formulation was used to model the dual-medium nature incorporating matrix system with high porosity and low permeability and fracture network with low porosity and high permeability. After matching PVT experiments, a ten pseudo-components fluid model was generated for running compositional simulation. The miscible hydrogen and carbon compounds injection was simulated as an effective enhanced oil recovery approach. Sensitivity analysis such as timing of injection gas, injection rate, well spacing and completion interval have proposed the optimal condition for the miscible hydrogen and carbon compounds flooding. The recommended optimum hydrogen and carbon compounds injection scenario is twice higher oil recovery compared with natural depletion. The results of this study illustrate further the practicability of pseudo-components splitting and lumping for compositional simulation to evaluate the performance of hydrogen and carbon compounds injection processes, and are of great importance using the dual-porosity dual-permeability method performing numerical simulation of naturally fractured hydrogen-carbonate reservoirs.     

A novel model and sensitivity analysis for viscoelastic polymer flooding in offshore oilfield

Polymer flooding has been widely used in petroleum industry. With the development of theory and technology, some problems in the existing models of polymer flooding appear during simulation. Based on the characteristics of polymer and offshore oilfield such as viscoelasticity, degradation effect and strong salt-sensitive effect, a novel model of viscoelastic polymer flooding is built, and the validation is verified. After comparing the distributions of effective viscosity and residual oil of taking account of elasticity and taking no account of elasticity, it is used to investigate the effects of injection rate, polymer molecular weight, salinity, degradation rate and well space.     

The occurrence of volatile and semi-volatile aromatic hydrocarbons in virgin olive oils from north-eastern Italy

Twenty eight mono- (MAHs) and polyaromatic hydrocarbons (PAHs) were simultaneously determined in fifty-four virgin olive oils from three successive crops in the same geographical region. MAHs such as: toluene, C2-, C3- and C4-benzenes, and PAHs species containing 2, 3 and 4 aromatic rings were detected and quantified. MAHs were predominant in all of the samples, and had a mean concentration of 677 μg/kg. The mean concentration of total light PAHs was 80 μg/kg. Mean concentrations of C3- and C4-benzenes, which had not been previously quantified in olive oils, were 268 and 35 μg/kg, respectively. Finally, differences among crop years were evaluated, and the hypothetical daily intake of each aromatic hydrocarbon through virgin olive oil consumption was derived. The mean intake of single aromatic hydrocarbons ranged from 0.1 to 3.1 μg/day, while the mean exposures calculated for total MAHs and light PAHs were 15.6 and 1.8 μg/day, respectively.     

Present state of corrosion inhibitors in Japan

In this report, the utilization, research and development of corrosion inhibitors in Japan and the action mechanism of corrosion inhibitors are explained, and their effects and future utilization are also described. In Japan, corrosion inhibitor was commercialized in the 1970s, and the use of these showed the rapid elongation as a countermeasure of the use of sea sand as an aggregate for the period 1975–1977 and the use of corrosion inhibitors decreased after 1979 because of the regulation for the total amounts of chloride in concrete in the standards. Then, amounts of concretes with corrosion inhibitors decreased in 1990s. However, in the civil engineering and construction industry fields, they seem to have to deal with the problem of increase of chloride content in concrete by the deregulation and the utilization of various industrial waste materials. We should consider the utilization of corrosion inhibitor from the new viewpoint.     

鄂尔多斯盆地奥陶系马家沟组规模性有效烃源岩的发现及其地质意义

尽管对于鄂尔多斯盆地奥陶系马家沟组天然气的来源问题一直都存在着不同的认识,但所有观点均不认为马家沟组自身发育TOC0.5%的规模性烃源岩。通过分析该盆地中东部奥陶系近年来大量新钻井的岩心和岩屑样品,揭示了马家沟组不同岩石类型烃源岩的有机质丰度特征,首次发现并证实马家沟组存在有机质丰度高的规模性有效烃源岩。研究结果表明:1马家沟组有效烃源岩的岩性主要为暗色薄层—厚层状含云泥岩、云质泥岩和泥云岩,其富集分布明显受沉积相的控制,马家沟组沉积期间海退期较海侵期更有利于规模性有效烃源岩的发育,层位上主要集中分布在马五上段,其次为马五中—下段、马三段和马一段;2平面上有效烃源岩围绕米脂盐洼呈双环带状分布,次级洼陷有效烃源岩呈中厚—厚层状,累计厚度大、有机质丰度高;3有效烃源岩在米脂凹陷中心和次级隆起则呈薄层状,累计厚度小、有机质丰度低;4有效烃源岩的有机碳含量变化范围为0.30%~8.45%,其生烃母质为浮游藻类和疑源类,有机质类型为腐泥型或偏腐泥混合型。结论认为:该盆地奥陶系有效烃源岩普遍处于过成熟阶段,以产干气为主,生气量大,是马家沟组天然气的主要贡献者。     

An explicit integral expression for the stress intensity factor of a semi-elliptic surface crack subjected to thermal transient loading

An explicit integral expression for the stress intensity factor of a semi-elliptic surface crack in a plate subjected to thermal transient loading was developed. The stress intensity factor of a semi-elliptic surface crack in a plate, which is exposed to a step change of fluid temperature, was calculated on the basis of the weight function method. The change of the stress intensity factor for a semi-elliptic surface crack subjected to an arbitrary change of the boundary fluid temperature was obtained by Duhamel integration for the product of the step function result and the time varying fluid temperature. The result obtained by the present method has shown good agreement with those obtained by the influence function method. As a practical application, a parametric analysis was performed for the crack behavior during the emergency cool down of reactor coolant in the reactor pressure vessel. Also, the present expression can be effectively applied to the simulation of fatigue crack growth of a semi-elliptic surface crack subjected to various thermal transient loading.     

Formulating and optimizing a combustion pathways for oil shale and its semi-coke

Enhanced technologies from oil recovery to unconventional fuels - oil shale, oil sands and extra-heavy oil – have in common complex chemical reactions processes. This paper is about the formulation and optimization of the chemical mechanism especially in oil shale and semi-coke combustion. The Levenberg–Marquardt algorithm was used to minimize the error between estimated values and the thermogravimetric data for combustion mechanisms of 4-steps and 3-steps proposed for the oil shale and its semi-coke respectively. The kinetic parameters such as reaction order, pre-exponential factor, activation energy and stoichiometric coefficients that affect drying, pyrolysis, oxidation and decarbonation reactions were estimated with success. The values of activation energies were 54–67 kJ mol^?1 for oil shale drying, 62–65 kJ mol^?1 for pyrolysis reaction, up to 100 kJ mol^?1 for Fixed Carbon (FC) oxidation reaction, and 162–418 kJ mol^?1 for decarbonation reaction. Regarding to the semi-coke combustion, the activation energies were 33 kJ mol^?1 for drying reaction, 211 kJ mol^?1 for oxidation reaction and 291 kJ mol^?1 for decarbonation reaction. The chemical reactions suggest reaction order superior to one, except to the decarbonation reaction at 3 K min^?1. Considering the estimated parameters, as well as a heating rate at 3 K min^?1, an oil shale containing about 20 wt.% of organic matter and 34.6 wt.% of CaCO₃, the species mass fractions formed during combustion process were 3.4 wt.% of FC, 10.6 wt.% of Oil, 3.3 wt.% of HC and 1.8 wt.% of CO. The fraction of CO₂ formed accounts a total of 21.6 wt.%. For a semi-coke containing 3.4 wt.% of FC and 40.6 wt.% of CaCO₃, its combustion formed 2.1 wt.% of CO. The CO₂ fraction from oxidation and decarbonation reactions accounts 10.2 wt.%, considering that the stoichiometric mass coefficient γ = 0.75 in decarbonation reaction.     

Fabrication of superhydrophilic and antireflective silica coatings on poly(methyl methacrylate) substrates

Silica nanoparticles of ca. 20 nm in size were synthesized, from which hierarchically porous silica coatings were fabricated on poly(methyl methacrylate) (PMMA) substrates via layer-by-layer (LbL) assembly followed by oxygen plasma treatment. These porous silica coatings were highly transparent and superhydrophilic. The maximum transmittance reached as high as 99%, whereas that of the PMMA substrate is only 92%. After oxygen plasma treatment, the time for a water droplet to spread to a contact angle of lower than 5° decreased to as short as 0.5 s. Scanning and transmission electron microscopy were used to observe the morphology and structure of nanoparticles and coating surfaces. Transmission and reflection spectra were recorded on UV–vis spectrophotometer. Surface wettability was studied by a contact angle/interface system. The influence of mesopores on the transmittance and wetting properties of coatings was discussed on the basis of experimental observations.     

Microcomputer-assisted temperature programmed desorption studies

An IBM-PC assisted ultra-high vacuum system for temperature programmed desorption studies is described. With the use of a self-constructed interface board and a commercial IEEE interface, the microcomputer controls the heating of the adsorbent and stores the partial pressure-temperature-time data from a quadrupole mass spectrometer and thermocouple. Hardware and software details are presented and discussed. Applications of the system are illustrated by the results of carbon monoxide desorption from CdTe(110) surface.     

Antioxidant activity of peanut seed testa and its antioxidative component,ethyl protocatechuate

The antioxidant activity of ethanolic extracts of peanut seed testa (EEPST) and its antioxidative component, ethyl protocatechuate (EP), was examined. It was found that EEPST and EP showed a dose-dependent activity on the inhibition of liposome peroxidation. EEPST and EP in the range of 50–500 mg/l were effective in protecting protein against oxidative damage. EEPST and EP at 100 mg/l showed 92.6% and 84.6% scavenging effect, respectively, on α,α-diphenyl-β-picrylhydrazyl radical, indicating that they act as a primary antioxidant. In addition, EEPST and EP, at a dose of 200 mg/l, showed 70.6% and 67.7% scavenging effect, respectively, on the hydroxyl radical. EEPST also exhibited a metal-binding ability, while EP did not. The inhibitory effect of EEPST on linoleic peroxidation correlated with their polyphenolic content. These results suggest that the antioxidant mechanism, for both EEPST and EP, could possibly be due to their scavenging effect on free radical and hydroxyl radical. In addition, its metal binding ability may contribute to antioxidant activity of EEPST.