Numerical study on the deformation of soil stratum and vertical wells with gas hydrate dissociation

Gas hydrate (GH) dissociates owing to thermal injection or pressure reduction from the well in gas/oil or GH exploitation. GH dissociation leads to, for exam-ple, decreases in soil strength, engineering failures such as wellbore instabilities, and marine landslides. The FLAC3D software was used to analyze the deformation of the soil stratum and vertical wells with GH dissociation. The effects of Young’s modulus, internal friction angle, cohesion of the GH layer after dissociation, and the thickness of the GH layer on the deformation of soils were studied. It is shown that the maximum displacement in the whole soil stratum occurs at the interface between the GH layer and the over-layer. The deformation of the soil stratum and wells increases with decreases in the modulus, internal friction angle, and cohesion after GH dissociation. The increase in thickness of the GH layer enlarges the deformation of the soil stratum and wells with GH dissociation. The hydrostatic pressure increases the settlement of the soil stratum, while constrain-ing horizontal displacement. The interaction between two wells becomes significant when the affected zone around each well exceeds half the length of the GH dissociation zone.     

Synthesis and Characterization of Catalysts Cu–ZnO Supported on Mesoporous Carbon FDU‐15

A new catalyst with uniformly distributed metal oxide is synthesized and characterized. The active centers Cu–ZnO of the designed catalyst are well distributed in the ordered mesoporous carbon FDU‐15 which has very high BET surface area and large pore volume. The effects of the amount of metal oxide loading, calcination temperature, and ramping rate on the resulting catalysts are investigated using N₂‐physisorption, X‐ray diffraction, and scanning and electron microscopy. The results show that the Cu–ZnO particle size increases with the metal loading and calcination temperature, whereas it decreases with the ramping rate. When the metal loading is 20%, the calcination temperature is 700 °C, and the ramping rate is 20 °C/min, uniform metal oxide particles well distributed on the carbon support are obtained.     

Strain Relaxation Related Photoluminescence Bands in Ge／Si Short Period Superlattices

Pure-Ge/Si short period superlattice (SPS) grown by gas source MBE(GSMBE) is studied by photoluminescence spectroscopy and Raman scattering spectroscopy.An abnormal band in photoluminescence is found in an intermediate range of Lsi between 1.9nm-2.9nm for samples with Lge fixed at 1.5ml.In contrast to a pure-Ge/Si quantum well,the energy of the band shows red-shift as Lsi increases .Raman scattering shows that Si-Si vibration related Raman shift reaches a minimum for samples with strongest PL intensity of the abnormal band .It is therefore concluded that the abnormal band is related with strain relaxation process.     

用于综合录井技术的在线快速气相色谱-四极杆质谱联用仪研制

研制了一种用于综合录井技术的在线快速气相色谱-四极杆质谱联用仪。采用隔膜泵直接抽取泥浆中脱出的气体样品直接引入气相色谱,通过气驱十通阀实现自动进样;快速分离后,样品中各组分依次进入四极杆质谱进行检测;四极杆质谱采用电子轰击源电离及选择离子扫描的方式,提供对碳氢化合物检测所需要的高灵敏度;仪器通过精确的时序控制实现周期循环进样分析,满足录井现场的实时监测需求。仪器采用安全易得的氮气作载气,对C1-C8烷烃、苯、甲苯、环己烷和甲基环己烷等油气组分进行快速在线分析,结果表明,C1-C5分析周期小于30 s,C1-C8周期小于85 s,最低检测浓度为0.0001%(V/V),线性范围高于5个数量级,适合于录井技术中油气组分分析。     

Modeling of pulsed spark discharge in water and its application to well cleaning

This paper presents a simulation model for the generation of strong pressure wave by means of pulsed spark discharge in water and its application to well cleaning. In the simulation model, one-dimensional time-dependent magnetohydrodynamic equations are coupled to a capacitive discharge circuit equation. A cylindrical conducting spark channel formed by electrical breakdown of water gap between a pair of electrodes is treated as a load of which resistance and inductance are allowed to change with time. For describing the spark channel properties accurately, precise calculations on thermodynamic properties and electrical conductivity are included in the simulation model. The simulation results show an excellent agreement with the experimentally measured shock pressure as well as the current and voltage waveforms. The simulation reveals that Joule heating of the spark channel during the very early phase of electrical discharge plays a key role in the formation of shock wave in water. The voltage on a capacitor at breakdown, the circuit inductance, and the resistance of the spark channel are found to be the most important parameters for the shock wave formation. With this technique, a pilot test for the cleaning of a clogged well has been performed in a water well which was constructed as a test-bed for riverbank filtration near the Anseong-cheon (river) in Korea. Well treatments have been carried out with an electrical energy of 510 J stored on a pulsed power system, at which the maximum shock pressure is measured to be around 7 MPa at the position of the well screen, i.e. 0.1 m away from the spark gap. A slug test shows 2.9 times improvement in the hydraulic conductivity of the well, which, combined with a visual inspection inside the well using an underwater camera, clearly demonstrates that the strong pressure wave generated by underwater spark discharge can effectively remove almost all incrustations formed in the well screen and thus improve well performance. Operating parameters for controlling the strength of shock pressure are discussed using the simulation model for extensive applications of the present technique to various types of water wells.     

Self-affine and ARX-models zonation of well logging data

Zonation of time series into models which their parameters are piecewise constant are important and well-studied problems. Geophysical well logging data often show a complex pattern due to their multifractal nature. In a multifractal system, any pieces of it are established by a distinct exponent that can characterize them. This feature has the capability to cluster them. Self-affine zonation by Auto Regressive model with exogenous inputs (ARX) is a new approach which places well logging segments in the clusters which are more self-affine against the other clusters. This approach was performed and compared with a conventional ARX zonation in the well logging data of three different oilfields in southern parts of Iran. The results showed a good accuracy for detecting homogeneous lithological segments and led to a precise interpretation process to update the reservoir architecture.     

The two-machine open-shop problem with unit-time operations and time delays to minimize the makespan

This paper addresses the problem of scheduling unit-time operations with integral and non-negative time delay considerations on a two-machine open-shop environment. The criterion to minimize is the makespan. Two well solvable cases and two approximation algorithms, with their worst-case analyses, are presented.     

金属平面半导体量子阱微腔自发发射

应用微腔腔量子电动力学和半导体量子阱物理,讨论了平面半导体量子阱微腔的自发发射,得到了腔结构、量子阱参量和注入载流子下的微腔自发发射谱和载流子寿命．计算发现由于微腔和量子阱分别对光子和载流子的限制,平面微腔可以增进自发发射,具有很强单方向性．     

表面修饰引发的ZnO纳米棒阵列膜的超疏水性

润湿性是固体表面的重要性质之一 ,它受控于固体表面自由能和表面粗糙度的大小 ,一般可用液体在固体表面接触角的大小来衡量 .由于水与超疏水表面 (水与固体表面的接触角大于 1 5 0°的表面 )的接触面积很小 ,通过水所发生的化学发应和化学键的形成受到限制 ,使这种表面具有防水、防污染和防氧化等多种功能 ,因而备受人们的关注 [1～ 6 ] .作为宽禁带半导体材料 ,Zn O以其独特的光电和催化等性质在短波激光器、气体传感器、高效催化剂、太阳能电池等方面具有广阔的应用前景 .表面润湿性的研究对于将 Zn O用于各种器件非常重要 .Pesika等 […     

高性能GaAs／AlGaAs量子阱红外探测器的研制

ＧａＡｓ／ＡｌＧａＡｓ多量了阱结构的红外探测器是近几年出现的一种新型红外探测器。本文对基基本原理作了介绍。并报导了最新研制成果；Ｄλ＝１．４２×１０＾１１ｃｍＨｚ１／２Ｗ＾－１＝Ｒλ＝２．３２×１０＾６Ｖ／Ｗ，峰值响应为８．５μｍ的高性能ＧａＡｓ／ＡｌＧａＡｓ量子阱红外探测器。