Effects of moderate pressure on premeability and viability of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> cells

With CO₂ and N₂ as the pressure media, the effects of the moderate pressure (0.1–1.0MPa) and the holding time on the conductivities of the cell suspension of Saccharomyces cerevisiae CICC1447 and Saccharomyces cerevisiae CICC1339, as well as the absorbances of the supernatant (after centrifuged) at 280 nm (A₂₈₀) and 260 nm (A₂₆₀) were determined. The membrane permeability of Saccharomyces cerevisiae CICC1447 increased significantly and the cell leakage was aggravated with the pressure increase. For Saccharomyces cerevisiae CICC1339, the conductivity of the cell suspension, A₂₈₀ and A₂₆₀ of the supernatant fluctuated with the pressure increase; as a whole, they increased with pressure. Different from high pressure, a moderate pressure not only remarkably improved the permeability of the yeast cell membrane, but also kept yeast cell viability; moreover, the integrity of the yeast cell membrane could be maintained. The first author and the fifth author contributed to the work equally.     

柴达木盆地西部北区N2^1～N2^2低渗非常规储层应力敏感特征分析

通过室内实验对柴达木盆地西部北区储层岩石的应力敏感性进行了研究。结果表明,岩石类型对该区储层应力敏感性具有重要的影响,风暴岩应力敏感性一般为中偏弱,而灰泥岩储层具强的应力敏感性。风暴岩的渗透率恢复率明显高于灰泥岩的渗透率恢复率。     

粉煤灰在油田开发中的应用

在对某热电厂粉煤灰全面的性能分析的基础上,介绍了一种以粉煤灰为主剂的水井用调剖剂。经室内实验分析和现场应用的效果分析,证明FP-2型粉煤灰类调剖剂的堵水调剖效果好,为粉煤灰的综合利用找出了一条新的应用途径。     

Effects of Tween 80 concentration as a surfactant additive on morphology and permeability of flat sheet polyethersulfone (PES) membranes

In this study, effects of Tween 80 (polyoxyethylene sorbitan monooleate) as a variable hydrophilic surfactant additive on morphology and permeability of flat sheet polyethersulfone (PES) membranes prepared from PES/polyethylene glycol (PEG)/n-methyl-2-pyrrolidone (NMP) system via phase inversion induced by immersion precipitation in water coagulation bath were investigated. Cross-sectional morphology of the prepared membranes was studied by scanning electron microscopy (SEM). Permeation performance of the prepared membranes was evaluated in terms of pure water permeability (L_P), water content, porosity, hydraulic permeability and thickness of the prepared membranes. It was found out that little addition of Tween 80 to the casting solution increases water content and porosity of the membrane support layer and enhances pure water permeability through the membranes.     

Autogenous healing of engineered cementitious composites under wet-dry cycles

Self-healing of Engineered Cementitious Composites (ECC) subjected to two different cyclic wetting and drying regimes was investigated in this paper. To quantify self-healing, resonant frequency measurements were conducted throughout wetting-drying cycles followed by uniaxial tensile testing of self-healing ECC specimens. Through self-healing, crack-damaged ECC recovered 76% to 100% of its initial resonant frequency value and attained a distinct rebound in stiffness. Even for specimens deliberately pre-damaged with microcracks by loading up to 3% tensile strain, the tensile strain capacity after self-healing recovered close to 100% that of virgin specimens without any preloading. Also, the effects of temperature during wetting-drying cycles led to an increase in the ultimate strength but a slight decrease in the tensile strain capacity of rehealed pre-damaged specimens. This paper describes the experimental investigations and presents the data that confirm reasonably robust autogenous healing of ECC in commonly encountered environments for many types of infrastructure.     

Compared imbibitions of ordinary and high performance concrete with null or positive water pressure head

A method to simultaneously measure the moisture diffusion coefficient, D_θ, of unsaturated concrete, and the saturated concrete hydraulic conductivity, K_l, was developed for cylindrical specimens placed on a container filled with water that could be maintained at a given hydraulic pressure. Ordinary Portland cement Concrete (OPC) with a moderate and High Performance Concrete (HPC) with a low water to cement ratio were tested. The time dependent distribution of water content in the specimens was measured using a non-intrusive method based on gamma-ray attenuation. The measurements were conducted with varying hydraulic head (positive or null). Boltzmann's transformation was used to analyze the experimental results obtained at different hydraulic pressures and the difference between the null (or atmospheric) and positive pressure results is used to accurately determine K_l and also D_θ . This paper will present the results obtained using this original method, possible interpretations and future research.     

Simulation of saturated fluid flow in packed particle beds—The lattice-Boltzmann method for the calculation of permeability from XMT images

Cone beam X-ray microtomography (XMT) instrumentation is a state-of-the-art non-invasive technology now used for several years to describe important characteristics of packed particle beds in three-dimensional (3D) detail. Many process engineering operations involve the transport of fluid in porous media. It is well known that the flow in porous media depends on the geometric properties of the pore network structure and in this regard X-ray microtomographic imaging captures the porous network structure of opaque packed particle beds which is later used for fluid flow analysis. The coupling of XMT 3D imaging with a novel fluid flow simulation method, known as the lattice-Boltzmann model (LBM), allows for direct local flow determination and micro-permeability calculations for complex porous structures. In this paper the methodology is briefly explained, implementations for some practical problems are addressed, the application of the technique from results for packed particle beds of interest are presented, and a comparison with experimental data is made.     

Study of Internal and External Leaks in Tests of Anode‐Supported SOFCs

A planar anode‐supported solid oxide fuel cell (SOFC) has been tested to investigate gas tightness of the electrolyte and the applied seals. Gas leaks reduce the efficiency of the SOFC and it is thus important to determine and minimise them. Probe gases (He and Ar) and a Quadrupole Mass Spectrometer were used to detect both internal (through electrolyte) and external (through seals) gas leaks. The internal gas leak through the electrolyte was quantified under different conditions, as was the external leak from the surroundings to the anode. The internal gas leak did not depend on the pressure difference between the anode and the cathode gas compartment, and can thus be described as diffusion driven. External leaks between the surroundings and the anode, but not the cathode gas compartment was observed. They were influenced by the pressure difference and are thus driven by both concentration and pressure gradients. The measured gas leaks deduced from the probe gas experiments and the total leak calculated from the deviation between the Emf defined by the gases and the cell OCV (which contains all gas leaks as well as effects of electronic leaks) were compared. Good agreement between the two measures was observed.     

童氏图版在低渗透油田中的改进与应用

本文在童氏含水率与采出程度关系式的基础上,通过对统计系数和边界条件的修正,研究出符合低渗透油田的童氏改进图版,并在石南31油田实践应用中加以验证,改进后的曲线计算结果更加准确,更加符合油田具体实际。     

低渗透油田IPR曲线与合理井底压力的确定

低渗透油田开发过程中,由于启动压力梯度的存在,低渗透油藏流体渗流过程变成非达西渗流,通过建立数学模型,求解IPR曲线。给出了油井最低允许流动压力的计算公式,对于低渗透油藏的开发具有指导意义。