井孔压力与地层应力集中诱导的偶极弯曲波的分裂

利用在大形变基础上叠加小扰动的非线性波动理论———声弹性理论 ,数值考察了井外均匀各向同性固体介质同时受井孔静压力和井外单轴水平压力作用时 ,Stoneley波和两种偏振的偶极弯曲波的相速度频散曲线 ,并研究了计算中用到的灵敏系数随频率的变化 .数值结果表明 ,模式波相速度频散曲线的变化主要受灵敏系数中对应的 3个三阶弹性常数的项控制 ;由井孔周围应力集中引起的沿单轴压力方向和垂直于该方向偏振的弯曲波发生分裂 ,同时随频率的增大 ,两条频散曲线产生交叉 ;井孔静压力的作用使两条频散曲线交叉点的位置发生变化 ,交叉点相速度值随井孔压力的增加而增大 ,但对应的频率值不变 .

非线性偶极-交换表面自旋波的包络孤立子解

介绍了非线性表面自旋波理论研究的新进展 ,并对前人的理论做了推广 ,针对具有非均匀交换各向异性的偶极 交换铁磁介质的非线性表面自旋波的性质和行为进行了较为系统的理论研究 .

偶极各向异性测量中钻孔应力集中的效应

由实验和理论给出了应力集中是如何影响钻孔周围速度场,以及速度场是如何影响偶极各向异性测量的。在低频率,偶极波主要易受远场应力的作用,即标准声波测井解释结果恰能得出最大应力方向。在高频率,偶极波主要受近场应力集中的影响,致使快速极化方向与最小构造应力的方向一致。这些效应使得在快速极化方向和慢速极化方向测得的偶极波散曲线产生了交叉。根据宽频带偶极资料,偶极波散曲线交叉可被用来作为应力诱发各向异性超过弱的固有各向异性的标志。

横波速度径向层析成像方法及应用研究

近来三维声波成像技术的一个重要进展是利用偶极子弯曲波反演地层径向横波速度剖面。确定地层径向横波速度变化对评价井壁稳定性、估算地应力和优化油藏生产等有着重要的意义。偶极横波测井激发的弯曲波低频探测较深,高频探测较浅,本文根据偶极弯曲波的频散特征,采用约束反演的方法求取地层径向横波速度变化。在实际测井中,经常会遇到偶极子弯曲波的频散曲线在高频时缺失或者不准确的情况,这会使约束反演方法产生误差。针对这一现象,本文提出利用理论频散数据进行高频约束,并通过数值模拟验证了改进后约束反演方法的正确性。本文给出了一个致密气层的横波速度径向剖面综合应用实例,发现地层径向横波速度变化程度与岩石脆性有很好的对应关系,最终的压裂效果由压前、压后正交偶极横波各向异性的变化得到了印证,压裂后油气产量提高。

位场小波分析的物理解释

采用二进小波变换 ,构造了位场基小波 ,通过简单模型 ,分析了位场信号小波分解与重构的物理实质 ,阐明了小波变换的频带分布与“归一化”位场空间分布的一致性 ,以及小波重构的规律 。

基于阵列声波测井技术的海上砂岩储层压裂效果评价方法

为满足海上砂岩储层压裂效果评价需求,基于压裂前后测量的阵列声波测井资料,研究并应用了纵波层析成像技术和偶极散射波技术进行储层压裂效果评价。纵波层析成像技术可以重建井壁附近地层径向声速剖面,通过对比压裂前后井壁附近地层声速的径向变化,可以评价近井壁储层水力裂缝的高度,但无法评价远井处储层的压裂效果;偶极散射波技术利用散射波能量分析井孔周围数十米范围内地层的非均质性,可以评价远井处水力裂缝的空间展布情况。上述2种技术相结合,可实现对储层近井壁和远井壁地层压裂效果的综合评价。采用该方法评价了海上调整井X1井的压裂效果,与压裂前相比,压裂后近井壁形成的裂缝使岩石声速明显降低,水力裂缝高度约为13.80 m,井周裂缝形成的散射波能量差异区域显示,在井眼周围至少14.00 m范围内形成了明显的压裂体积改造,说明压裂效果良好。该方法不仅可以准确判断近井壁和远井处水力裂缝的高度,还可以在一定程度上评价水力裂缝的径向长度。

Application of four-component dipole shear reflection imaging to interpret the geological structure around a deviated well

Acoustic reflection imaging in deep water wells is a new application scope for offshore hydrocarbon exploration.Two-dimensional(2 D)geological structure images can be obtained away from a one-dimensional(1 D)borehole using single-well acoustic reflection imaging.Based on the directivity of dipole source and four-component dipole data,one can achieve the azimuth detection and the three-dimensional(3 D)structural information around the wellbore can be obtained.We first perform matrix rotation on the field fourcomponent data.Then,a series of processing steps are applied to the rotated dipole data to obtain the reflector image.According to the above dipole shear-wave imaging principle,we used four-component cross-dipole logging data from a deviated well in the South China Sea to image geological structures within 50 m of a deviated well,which can delineate the structural configuration and determine its orientation.The configuration of near-borehole bedding boundaries and fault structures from shear-wave imaging results agrees with those from the Inline and Xline seismic profiles of the study area.In addition,the configuration and orientation of the fault structure images are consistent with regional stress maps and the results of the borehole stress anisotropy analysis.Furthermore,the dip azimuth of the bedding boundary images was determined using borehole wall resistivity data.Results of this study indicate that integrating borehole acoustic reflection with seismic imaging not only fills the gap between the two measurement scales but also accurately delineates geological structures in the borehole vicinity.

Wideband dipole logging based on segmen linear frequency modulation excitation

A wideband dipole signal is required for dipole dispersion correction and nearborehole imaging. To obtain the broadband flexural wave dispersion, we use a nonlinear frequency modulation （NLFM） signal and propose a segment linear frequency modulation （SLFM） signal as the dipole excitation signal to compensate for the excitation intensity. The signal-to-noise ratio （SNR） of the signal over the entire frequency band is increased. The finite-difference method is used to simulate the responses from a Ricker wavelet, a linear frequency modulation （LFM） signal, an NLFM signal, and an SLFM signal in two borehole models of a homogeneously hard formation and a radially stratified formation. The dispersion and radial tomography results at low SNR of the sound source signals are compared. Numerical modeling suggests that the energy of the flexural waves excited by the Ricker wavelet source is concentrated near the Airy phase. In this case, the dispersion is incomplete and information regarding the formation near or far from the borehole cannot be obtained. The LFM signal yields dispersion information near the Airy phase and the high-frequency range but not in the low-frequency range. Moreover, the information regarding the formation far from the borehole is not accurate. The NLFM signal extends the frequency range of the flexural waves by compensating for the excitation intensity and yields information regarding the formation information, but it is not easy to obtain. The SLFM signal yields the same results as the NLFM signal and is easier to implement. Consequently, the dipole detection range expands and the S-wave velocity calculation accuracy improves.

The Kelvin Wave Processes in the Equatorial Indian Ocean during the 2006-2008 IOD Events

The present study investigates the role of Kelvin wave propagations along the equatorial Indian Ocean during the 2006-2008 Indian Ocean Dipole(IOD).The 2006 IOD lasted for seven months,developing in May and reaching its peak in December,while the 2007 and 2008 IODs were short-lived events,beginning in early May and ending abruptly in September,with much weaker amplitudes.Associated with the above IODs,the impulses of the sea surface height(SSH) anomalies reflect the forcing from an intraseasonal time scale,which was important to the evolution of IODs in 2007 and 2008.At the thermocline depth,dominated by the propagation of Kelvin waves,the warming/cooling temperature signals could reach the surface at a particular time.When the force is strong and the local thermocline condition is favorable,the incoming Kelvin waves dramatically impact the sea surface temperature(SST) in the eastern equatorial Indian Ocean.In July 2007 and late July 2008,the downwelling Kelvin waves,triggered by the Madden-Julian Oscillation(MJO) in the eastern and central equatorial Indian Ocean,suppressed the thermocline in the Sumatra and the Java coast and terminated the IOD,which made those events short-lived and no longer persist into the boreal fall season as the canonical IOD does.

A Dipole Pattern of Summer Precipitation over Mid-high Latitude Asia and Related Snow Cover Anomalies in the Preceding Spring

A dipole pattern of summer precipitation over the mid-high latitudes of Asia, which is characterized by opposing summer precipitation variations between the Mongolian and Northeast China(MNC) region and the West Siberian Plain(WSP), is found to be clear and stable on both interdecadal and interannual scales during 1981–2011. Spring snow cover anomalies over a small region within the WSP and the Heilongjiang River(HR) region are closely related to the variation of this dipole mode during the subsequent summer, and they can therefore be considered as forecasting factors. Our statistical results imply a potential process explaining the relationship between the spring snow anomalies and the summer rainfall dipole. Corresponding to the snow anomalies, Rossby waves propagate along a path from the WSP region, via the Mongolian Plateau, to the Stanovoy Range during summer. At the same time, Rossby-wave energy divergences and convergences along this path maintain and reinforce an anomalous cyclone and anticyclone pairing over the Asian continent, which is significantly linked to opposite summer precipitation anomalies between the MNC and WSP regions. Numerical experiments are needed to further confirm the above conjecture and demonstrate the detailed physical mechanisms linking the spring snow cover anomalies and summer precipitation dipole.

One Step to Generate Cluster States Using Dipole-Induced Transparency in a Cavity-Waveguide System

We present a very simple scheme for generating four-qubit cluster states with one step using paritymeasurement based on dipole-induced transparency in a cavity-waveguide system.The scheme only uses the photondetectors to check the parity of the spatially separated dipole,which are the same (even parity) or different (odd parity)through measuring the light fields in the waveguide.The initial entangled states remain after nondetective identificationand they can be used for successive tasks.

Gauge Invariance of a Time-Dependent Harmonic Oscillator in Magnetic Dipole Approximation

A manifestly gauge-invariant formulation of non-relativistic quantum mechanics is applied to the case of time-dependent harmonic oscillator in the magnetic dipole approximation. A general equation for obtaining gauge-invariant transition probability amplitudes is derived.

Research on Distribution of Electric Dipole Field based on Applied Mathematics and Computer

The paper analyze the polarization of study dielectric that produced field by dipole, medium field plays an important role in electromagnetic wave radiation. The electric field expression for electric dipole electric field distribution in ordinary textbooks only give a special direction, This paper introduces in detail the formula of the electric dipole in the space of an arbitrary point excitation electric field, and use computer sottware to simulate the distribution pattern of electric dipole, and gives some typical figures for reference.

声波测井新理论和方法进展

在对声波测井的应用背景、基础方法的推出和理论发展过程进行综述的基础上,着重介绍了近10多年声波测井理论和方法的新进展.结合偶极声波测井技术的兴起和地层各向异性的探测,就相关的基础理论新成果和典型新方法的应用分别进行了评述,也对井孔倏逝波机制和声(震)电效应这类更着眼于进一步应用的物理问题做了概述.文章每一部分都对存在的问题和值得开展的工作提出了建议,并提供了较详细的参考文献,供有兴趣的读者方便查阅.

Study on HPM Power Measurement by Dipole Aatenna

In order to reduce the gain of a receiving antenna in HPM power measurement,especially in lower frequency, a low gain dipole antenna of L band is designed.By theoretical analysis and numerical simulation,the optimized results of the antenn are obtained:its central frequency is 1.75GHz,the variety of gain is less than 1.1dB in frequency band 1.70—1.80GHz,the estimated value of the power capacity of the antenna is 0.1MW,which can satisfy the demand of corresponding measurement.