Research on velocity and acceleration geophones and their acquired information

Based on the research of two geophone types （10 Hz moving-coil velocity and piezoelectric acceleration） and their velocity and acceleration parameters, frequency response functions have been determined, as well as the differences between them. Also, shock- vibration tests have been accomplished, not only to explain the two shock response signal differences, but also to analyze the response signal characteristics and its ability to carry information. In addition, seismic data acquisition experiments have been carried out under comparable conditions in the field. A contrast analysis of shot gathers and stack profiles acquired with the two geophone types is given in this paper. The results show that the acceleration signal from the acceleration geophone has a better advantage in terms of high signal-to-noise ratio, high accuracy, high resolution, and quantity of information to better meet current and future requirements for seismic exploration.

Analysis of geophone properties effects for land seismic data

The properties of the seismic geophones are important factors for high-resolution seismic exploration and have a great influence on data quality. For this reason, we have tested three kinds of geophones currently used in several regions with different geological features： desert, saline-alkali farmland, and carbonate areas in mountainous regions in order to test their property indexes. Based on the geophone vibration equation and from the property index effects ofgeophone and the connection of the geophones on seismic data, we analyzed seismic data quality acquired inthe tested regions and suggest that suitable geophone property indexes, reasonable choice of geophone types, and the suitable geophone connection can enhance the signal/noise ratio of seismic data.

Locating microseismic sources based upon L-shaped single-component geophone array:A synthetic study

We have developed a type of L-shaped single-component geophone array as a single station(L-array station)for surface microseismic monitoring.The L-array station consists of two orthogonal sensor arrays,each being a linear array of single-component sensors.L-array stations can be used to accurately estimate the polarization of first arrivals without amplitude picking.In a synthetic example,we first use segmentally iterative ray tracing(SIRT)method and forward model to calculate the travel time and polarization of first arrivals at a set of L-array stations.Then,for each L-array station,the relative delay times of first arrivals along sensor arrays are used to estimate the polarization vector.The small errors in estimated polarization vectors show the reliability and robustness of polarization estimation based on L-array stations.We then use reverse-time ray-tracing(RTRT)method to locate the source position based on estimated polarizations at a set of L-array stations.Very small errors in inverted source location and origin time indicate the great potential of L-array stations for source localization applications in surface microseismic monitoring.

Design of ground-airborne TEM three-component air-core coil sensor

Transient electromagnetic method (TEM),as a non-seismic geophysical exploration mainstream electromagnetic method,is widely used in oil,gas,mineral and other underground resources exploration areas. The coil sensor is generally used to collect data. In view of the problems of incomplete information of the abnormal body and the data loss in the existing TEM single-component coil sensor,a three-component TEM coil sensor is designed. By analyzing the relationship between sensor sensitivity and coil structure parameters,the coil structure and turns are designed. By analyzing the frequency response characteristics of the TEM magnetic field sensor,the signal distortion is reduced by using the under-damped matching mode. By analyzing the distribution of various noise sources of the magnetic sensor,the appropriate amplifier is selected to reduce the background noise. Finally,a three-component TEM induction magnetic field sensor is designed. The weight of the sensor is controlled at 3.2 kg and the working frequency is 10 mHz-10 kHz. The background noises of X and Y components probably keep in 1.5×10^-8 V/ Hz and sensitivities are 8.4 and 9.8 nT/s,respectively,the background noise of vertical component is 2.1× 10^-7 V/ Hz and sensitivity is 18.5 nT/s. Compared with the existing single-component TEM receiving magnetic field sensor,the designed sensor realizes the signal acquisition of three components. Without too much increase in volume and total weight,it improves the sensitivity of the sensor and reduces the background noise,thus the signal-to-noise ratio (SNR) of the signal is improved.

Determination of Direction of Arrival of Seismic Wave by a Single Tri-axial Fiber Optic Geophone

A fiber Bragg grating (FBG) geophone and a surface seismic wave-based algorithm for detecting the direction of arrival (DOA) are described. The operational principle of FBG geophone is introduced and illustrated with systematic experimental data, demonstrating an improved FBG geophone with many advantages over the conventional geophones. An innovative, robust, and simple algorithm is developed for obtaining the bearing information on the seismic events, such as people walking, or vehicles moving. Such DOA estimate is based on the interactions and projections of surface-propagating seismic waves generated by the moving personnel or vehicles with a single tri-axial seismic sensor based on FBGs. Of particular interest is the case when the distance between the source of the seismic wave and the detector is less than or comparable to one wavelength (less than 100 m), corresponding to near-field detection, where an effective method of DOA finding lacks.

Three-Component Model for Bidirectional Reflection Distribution Function of Thermal Coating Surfaces

We present a bidirectional reflection distribution function （BRDF） model for thermal coating surfaces based on a three-component reflection assumption, in which the specular reflection is given according to the microfacet theory and Snell＇s law, the multiple reflection is considered Nth cosine distributed, and the volume scattering is uniformly distributed in reflection angles according to the experimental results. This model describes the reflection characteristics of thermal coating surfaces more completely and reasonably. Simulation and measurement results of two thermal coating samples SR107 and S781 are given to validate that this three-component model significantly improves the modeling accuracy for thermal coating surfaces compared with the existing BRDF models.

Low-Frequency Waves in Cold Three-Component Plasmas

The dispersion relation and electromagnetic polarization of the plasma waves are comprehensively studied in cold electron, proton, and heavy charged particle plasmas. Three modes are classified as the fast, intermediate, and slow mode waves according to different phase velocities. When plasmas contain positively-charged particles, the fast and intermediate modes can interact at the small propagating angles, whereas the two modes are separate at the large propagating angles. The near-parallel intermediate and slow waves experience the linear polarization, circular polarization, and linear polarization again, with the increasing wave number. The wave number regime corresponding to the above circular polarization shrinks as the propagating angle increases. Moreover, the fast and intermediate modes cause the reverse change of the electromagnetic polarization at the special wave number. While the heavy particles carry the negative charges, the dispersion relations of the fast and intermediate modes are always separate, being independent of the propagating angles. Furthermore, this study gives new expressions of the three resonance frequencies corresponding to the highly-oblique propagation waves in the general three-component plasmas, and shows the dependence of the resonance frequencies on the propagating angle, the concentration of the heavy particle, and the mass ratio among different kinds of particles.

Application of a New Qeneration of Geophonesto Improve Seismic Acquisitionin Onshore-offshore Transition Areas

In this paper, we review the differences between velocity geophones （VG） and acceleration geophones （AG） and their effect on seismic signals acquired in onshore-offshore transition areas. We present a new generation of Land Piezoelectric Geophone （LPG） and analyze its performance. Our field experiments demonstrate that our new LPG can be used to substitute for VGs in order to eliminate phase, frequency and energy differences between different geophone systems commonlv used in transition areas.

Dark and multi-dark solitons in the three-component nonlinear Schrodinger equations on the general nonzero background

We exhibit some new dark soliton phenomena on the general nonzero background for a defocusing three-component nonlinear Schrodinger equation. As the plane wave background undergoes unitary transformation SU(3), we obtain the general nonzero background and study its modulational instability by the linear stability analysis. On the basis of this background, we study the dynamics of one-dark soliton and two-dark-soliton phenomena, which are different from the dark solitons studied before. Furthermore, we use the numerical method for checking the stability of the one-dark-soliton solution. These results further enrich the content in nonlinear Schrodinger systems, and require more in-depth studies in the future.

Statistical Average of Spin Operators for Calculation of Three-Component Magnetization （II）： Solution of Equation

In this paper, the solution of Chebyshev equation with its argument being greater than 1 is obtained. The initial value of the derivative of the solution is the expression of magnetization, which is valid for any spin quantum number S. The Chebyshev equation is transformed from an ordinary differential equation obtained when we dealt with Heisenberg model, in order to calculate all three components of magnetization, by many-body Green＇s function under random phase approximation. The Chebyshev functions with argument being greater than 1 are discussed. This paper shows that the Chebyshev polynomials with their argument being greater than 1 have their physical application.

Three-Component Coupling Catalyzed by Phosphine: Preparation of α-Amino γ-Oxo Acid Derivatives

The three-component coupling reaction of ethyl propiolate (1), phthalimide (2), and aldehyde (3) catalyzed by tripheny- lphosphine, was developed. A solution of an equivalent amount of 1 and 2 in benzaldehyde (3a) in the presence of 30 mol% of PPh3 was heated at 100?C for 48 h to give N-(1-ethoxycarbonyl-3-oxo-3-phenylpropyl)phthalimide (4a) in 83% yield. This reaction was thought to proceed via vinylphosphonium salt formed from the reaction of ethyl propiolate (1) with triphenylphosphine in situ.

Localized waves in three-component coupled nonlinear Schrdinger equation

We study the generalized Darboux transformation to the three-component coupled nonlinear Schr ¨odinger equation.First-and second-order localized waves are obtained by this technique.In first-order localized wave,we get the interactional solutions between first-order rogue wave and one-dark,one-bright soliton respectively.Meanwhile,the interactional solutions between one-breather and first-order rogue wave are also given.In second-order localized wave,one-dark-one-bright soliton together with second-order rogue wave is presented in the first component,and two-bright soliton together with second-order rogue wave are gained respectively in the other two components.Besides,we observe second-order rogue wave together with one-breather in three components.Moreover,by increasing the absolute values of two free parameters,the nonlinear waves merge with each other distinctly.These results further reveal the interesting dynamic structures of localized waves in the three-component coupled system.

Statistical Average of Spin Operators for Calculation of Three-Component Magnetization

When one wants to calculate all the three components of magnetization of Heisenberg model under random phase approximation, at least one of the components should be the solution of an ordinary differential equation. In this paper such an equation is established. It is argued that the general expressions of magnetization for any spin quantum number S suggested before are the solution of the ordinary differential equation.

A wireless geophone based on STM32

Seismic geophone is the key instrument for seismic data acquisition in the fields of oil and gas exploration and other relevant fields.It plays an important role in data quality,subsequent processing and interpretation.Aiming at the shortcomings of the existing geophones,such as large volume,heavy weight,unable to monitor in real-time,and heavy workload of data transmission and storage,this paper designs and implements a wireless geophone based on STM32 embedded microcontroller.It is mainly composed of STM32 microcontroller,acceleration sensor,global positioning system(GPS)module,Wi-Fi module and real-time seismic data receiving and processing module.Firstly,the acceleration of vibration in three directions is sensed by the acceleration sensor;secondly,the sampling and analog-to-digital conversion of the vibration data is controlled by the microcontroller;thirdly,the vibration and GPS data are sent to the personal computer(PC)through Wi-Fi,and the personal coomputer PC-side software module completes the reception,display,monitoring and storage of the seismic data;finally,the feasibility and effectiveness of the designed wireless geophone are verified through actual seismic data acquisition experiments.

井中永置式套管外三分量光纤MEMS地震检波器研究

针对非常规油气井套管外永置式微振动监测,研制了一种基于光纤法布里帕罗(F-P)干涉原理和微机电(MEMS)技术的三分量光纤MEMS地震检波器,将微地震信号转化为F-P腔长的变化,通过超快光谱探测技术和动态白光干涉解调技术实现高速解调。设计并理论仿真了μm/g量级的高灵敏度MEMS加速度芯片,突破大深度双面套刻工艺完成芯片样品制造。采用高集成度小型化结构设计、无胶封装工艺设计和陶瓷微加工工艺实现25 mm微型外径,满足套管外永置式安装要求,提高了高温检测精度。在实验室完成了检波器与标准电学加速度计的性能对比测试,结果表明:检波器可耐受175 MPa高压和180℃高温,灵敏度分别为1.2382,1.2590,1.0862μm/g,工作频带为0~350 Hz,量程为±5 g,线性度误差<0.01%,抗横向串扰能力<5%。研制的检波器耐高温高压、尺寸小巧、灵敏度高、线性度良好,在非常规油气井储层压裂改造和采油气生产过程中,永置式套管外的三分量光纤MEMS地震检波器可以发挥重要的监测作用。

检波器测试仪测试信号时序分析

动圈式检波器由于自身线圈结构的特点,在测试中不可避免会产生和引入各种脉冲振荡等干扰信号,本文通过对测试仪在测试直流电阻、阻尼系数、自然频率和灵敏度、失真度等过程时序信号的详尽分析,重点分析了其测试阻尼系数、自然频率和灵敏度等三项参数时阻尼衰减震荡信号的信号衰减特征,在此基础上给出了检波器测试和测试仪设计应用及校准中需要注意的问题。

宽频拖曳式地震检波器的面波精细化探测成像

传统的主动源面波仪采用锥形速度型检波器,具有频带窄、纵向分辨率低的缺点。传统装置移动测点需人工手动逐一移动检波器,无法低成本快速采集高密度面波数据,横向分辨率低。文中提出适应于硬化路面的拖曳式地震面波数据采集方法,设计重力耦合加速度检波器,线性、阵列拖曳式检波器串结构,提出高采样以提高面波探测精度的方法,实现高密度、小道距、高采样率、宽频数据采集。分析模型数据和实测数据在不同采样率时的结果表明,高采样能压制噪声干扰增强低频能量,保证足够的探测深度;检波器采集的面波数据,能保证在足够的深度范围内精细地刻画速度层的变化,查明潜在的塌陷位置。将拖曳式地震检波器应用于城市道路塌陷探测,体现高效采集、精细探测的优势。

对3种典型检波器及其数据的几点看法

动圈式检波器与压电式检波器是当前石油地震勘探中应用最为广泛的两类检波器,典型代表包括动圈式速度检波器、水中压电式压力检波器以及陆上压电式加速度检波器。分析了3种检波器的物理结构、力学模型、等效电路以及传输函数,实际数据证明动圈式检波器拾取的地表振动速度与陆地压电检波器拾取的地表振动加速度在主要频带内是等效的,但后者一致性稍差。水中压电式检波器(简称水检)是压力型检波器,不是加速度型检波器,其与动圈式速度检波器或者MEMS加速度检波器(简称陆检)是组成双检海底电缆(OBC)与海底节点(OBN)施工、采用双检合并技术消除水层鸣震的装备基础。当前双检合并技术的几个假设前提,如地震波场是平面波场,检波器距离海底非常近但二者并不接触,不考虑耦合效应,不考虑检波系统的机电效应等,在实际生产中并不满足。因此,提高双检合并技术的实用性需要对以上假设条件进行更深入的研究并采取相应的工程措施。考虑到检波器的主要功能是“忠实地记录大地振动”,野外经由电路提频的做法不应提倡。此外,对比了容易混淆的两种检波器分类方法并清晰地展示了检波器的分类标准及其对数据的影响。