裂缝性地层声波全波列的数值模拟及时频特征研究

发布时间：2018-01-08 18:22

本文关键词：裂缝性地层声波全波列的数值模拟及时频特征研究　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：声波全波列测井的核心是运用声波在岩层中传播的不同特征,获得所测岩层的岩石物理参数,从而判断地层的岩性以及是否为储集层等特征。声波测井数据的处理解释方法主要分为时间域方法和频率域方法。都是建立在慢度的提取的基础上,通过各组分波的慢度随井深的变化曲线来判断附近地层的性质。时间域的慢度提取方法包括门限法、能量积分法以及慢度-时间相关法等,是从信号时间域上入手。频率域的慢度提取方法是对声波全波列信号进行傅里叶变换,得到其每个组分波的频谱及频散曲线,包括频谱相位分析法以及Prony方法等。声波信号中包含物理量有:时间、频率和能量。慢度的提取忽略了信号的频谱特征,虽然声波测井信号的频谱信息能够通过傅里叶变换方法求出,但是其忽略了时间域上的信息。时频分析方法的优点在于既有频率域信息又有时间域信息,其将声波信号的基本物理量时间、频率和能量在时间-频率坐标轴上表现出来。针对声波全波列信号的特征,因为在相同时间处可能有多个组分波的频率响应,并且时间和频率较接近,所以利用单一的时频分析方法处理效果并不理想。本文创新应用希尔伯特-黄变换(Hilbert-Huang变换)中的经验模态分解(Empirical Mode Decomposition)即EMD分解联合同步挤压小波变换(Synchrosqueezing Transform)即SST变换,通过对不同EMD筛选方法进行编程实现,找到一种适合阵列声波测井信号的筛选方法,将分解得到的固有模态函数(Intrinsic Mode Function)即每个IMF做SST,旨在得到个各组分波的时频特征,进而对不同裂缝性储集地层声波信号的时频特征进行研究。本文研究内容包括:第一,应用希尔伯特变换(HHT)中的经验模态分解(EMD)联合同步挤压小波变换(SST)方法,首先针对不同EMD筛选方法进行编程实现,选取对阵列声波信号频率筛选效果较好的方法,对阵列声波信号进行分解,然后对每个固有模态函数做同步挤压小波变换,针对每个IMF得到的时频图,区分阵列声波全波列信号中个各组分波成分。并针对井段处理提出了时频分布的时间边缘和频率边缘特征,进而得到时频特征随深度变化规律,进而对裂缝及油水层时频特征进行评价。第二,应用有限差分法,使用交错网格方法,根据井孔波动方程推导了在柱坐标系下的速度—应力有限差分公式,选取了合适的吸收边界及声源函数进行编程,模拟了井外为均匀介质的硬地层及软地层、含裂缝地层以及裂缝中含有不同流体的地层的声波全波列的特征,进而用第一部分介绍的方法进行时频分析,从而总结出数值模拟的地层中裂缝在含油水时的声波时频特征。第三,选取不同井孔阵列声波测井实测数据,对数据进行预处理后,应用第一部分介绍的方法,选取多个深度段的数据进行分析处理,得到每个IMF的时频图以及时间边缘和频率边缘特征,对比第二部分得到的时频特征,反演地层中裂缝发育以及裂缝中含流体情况。通过上面的分析,可以得到以下结论:1.本文应用了联合时频分布方法,应用了EMD分解的滤波特性,以及同步挤压小波变换的高分辨率特性。对含裂缝的地层的阵列声波的时频特征进行了分析。对EMD的不同筛分方法进行了编程实现,发现应用稳定性定理的稳定点均值筛分方法对阵列声波测井数据的筛分效果最佳。2.阵列声波信号的时频特征图中,由于纵波的幅度相对横波及斯通利波较低,所以在时频图上无法完全的显示。本文应用了时间域与频率域的联合纵波提取方法,因为纵波的到时最早,频率最高的特点,对全波列信号在频率上进行高通滤波可以提取纵波;在时间域上,由于新的组分波首波与前一组分波的相位具有不连续性,对信号进行相位求导,能够将不连续的点凸现出来,同样在瞬时频率图中为一个跳变点,据此可以在时间域区分各个组分波。3.应用有限差分法可以有效的模拟均匀地层的情况。在模拟均匀硬地层时发现,本文的纵波提取方法可以有效的得到纵波的时频特征,应用EMD分解所得到的IMF2、IMF3中可以得到斯通利波的时频特征。这里引用了时间边缘以及频率边缘方法,可以对不同源距以及不同深度的数据进行分析。硬地层的时间边缘图可以看到随着源距的变化,斯通利波的主峰出现的时间呈正相关直线的增加;而频率边缘图中由于伪瑞利波的影响,频率边缘图表现的不规律。针对软地层的情况:本文设置了不同的参数,发现在相同的源的情况下,随着纵波在地层中的传播速度的变化,纵波的频率有所变化,纵波速度越大,其频率越小。分析缘由,可能是因为纵波速度越大时,到达接收器的时间越短,所以震源激发的纵波的频率就越接近震源的主频,所以纵波速度越大,对应的频率有所降低。4.应用有限差分法模拟了井外均匀地层在含有一条水平裂缝时的情况。分别对裂缝中的流体特征进行了不同参数的设置。发现裂缝内流体设置为水时,声波在穿过裂缝后,其各个组分波的到时均有延后,且幅度有大幅度降低。对纵波进行了提取,发现纵波在穿过裂缝后,其频率稍有减小,而频率幅度大大降低;当裂缝内流体设置为油时,声波在穿过裂缝后,各个组分波有同样的到时延后特征,纵波在经过含油的裂缝后,其主频表现了明显的降低。5.选取了辽河油田东部凹陷地区的实际测井数据,选取了既含有低角度裂缝又为油层或水层的同岩性的数据进行分析,主要针对纵波的时频特征,研究发现:相对致密玄武岩,含水层的玄武岩与含油层的玄武岩的纵波的时频特征为,纵波的波至相对延后,纵波的频率在油层时衰减的较多,而在水层时相对衰减程度较小。6.选取了辽河油田东部凹陷地区的实际测井数据,应用EMD分解与同步挤压小波变换对除纵波以外的组分波在致密地层以及含油水层的时频特征情况进行了分析,发现声波经过水层时横波衰减严重,高频波的频率幅度有所衰减,斯通利波的幅度也有较大的衰减,低频斯通利波频率的幅度的衰减较小;声波在经过油层时声波的大部分能量都集中在了横波以及伪瑞利波成分中,横波的到时延后,高频成分的幅度较高,斯通利波衰减非常严重。7.最后对反射斯通利波进行了研究,在模拟的均匀地层在含有一条水平裂缝时的情况,因为IMF3分量中包含了斯通利波的主要成分,所以对IMF3分量进行提取,从时间边缘图上可以很明显的看到反射斯通利波的存在,即时间边缘图中倒着的“V”字形波纹。对1m的源距单独分析,可以在时频图中准确的看到反射斯通利波的波峰以及频率的大小。反射斯通利波可以用于:其与直达的斯通利波之间的距离可以判断裂缝的发育位置;根据反射斯通利波的反射的能量可以来判断裂缝的大致宽度,反射能量越大,裂缝宽度越大。
[Abstract]:The core of full wave acoustic logging is different characteristics by using the acoustic wave propagation in rock, the rock physical parameters measured by strata, lithology and to determine whether the layer features such as reservoir. The method of processing and interpretation of acoustic logging data is divided into time domain method and frequency domain method are based on the extraction. The slowness, through each component wave slowness with well depth curve to determine the nature of the formation near. The slowness extraction method in time domain including threshold method, energy integral method and slowness time correlation method, starting from the signal time domain. The slowness extraction method in frequency domain is the Fourier transform of the full wave signal, and the frequency spectrum of each component of the wave dispersion curves, including phase spectrum analysis method and Prony method. The acoustic signal contains physical quantity: time, frequency and energy. The extraction slowness ignores the spectral characteristics of the signal, while the spectrum information of acoustic logging signal can be obtained by Fourier transform method, but it ignores the time domain information. The time-frequency analysis method has the advantages of frequency domain information and time domain information, the basic physical quantity time of acoustic signals. The frequency and energy reflected in the time - frequency axis. According to the characteristics of full wave acoustic signals at the same time, because there may be multiple component wave frequency response, and the time and frequency are similar, so the use of a single time frequency analysis method of treatment effect is not ideal. The innovation of the application of Hilbert Huang transform (Hilbert-Huang transform) in empirical mode decomposition (Empirical Mode Decomposition) EMD decomposition combined with wavelet transform (Synchrosqueezing Transform) extrusion SST transform, according to the different EMD screening method of programming, to find a suitable array acoustic logging signal screening method, the decomposed intrinsic mode function (Intrinsic Mode Function) that each IMF do SST, to get the time-frequency characteristics of a wave components, and then set on time frequency characteristics of acoustic signals of different strata of fractured reservoirs the content of this paper includes: first, the application of Hilbert transform (HHT) in the empirical mode decomposition (EMD) combined with synchronous extrusion wavelet transform (SST) method, according to the different screening methods of EMD programming, selection method of better screening of array acoustic signal frequency decomposition of array acoustic signal, and then each the intrinsic mode function as synchronous extrusion wavelet transform, for each IMF to obtain the time-frequency map, distinguish array full wavetrain acoustic signal components in a wave component. And for wells treatment The time and frequency of edge edge feature of time-frequency distribution, and then get the change rule of time-frequency characteristics with depth, then to evaluate the frequency characteristics of cracks and oil and water. Second, the application of finite difference method, using staggered grid method, according to borehole wave equation in cylindrical coordinates velocity stress Co. the difference formula is derived, selecting the appropriate absorption boundary and the source function programming, simulated well for homogeneous and soft hard rock strata, characteristics of sound with different crack formation and fracture fluid in the formation of full wave, and then the first part introduces the method of time-frequency analysis, thus summed up the numerical simulation of cracks formation in oil containing the acoustic frequency characteristics. Third measured data of different borehole array acoustic logging, after preprocessing the data, the first part introduces the method of application, Select multiple depth data analysis, get each IMF time frequency and time frequency map edge and edge features, the second part compares the obtained time-frequency characteristics, fluid containing fractured strata and fracture inversion. Through the above analysis, can get the following conclusions: 1. the application of frequency distribution method the combined application of EMD decomposition, filtering characteristics, wavelet transform and synchronous extrusion of the high resolution characteristics. The time-frequency characteristics of acoustic array with crack formation are analyzed. Different screening methods of EMD programming, found that the time-frequency feature map screening effect mean screening method of stable point application stability theorem the data of array acoustic logging best.2. array acoustic signal, the P-wave amplitude relative shear wave and Stone wave is relatively low, so in the time-frequency map can not fully display The application of combined wave. Time domain and frequency domain extraction method, because when the first wave characteristics, the highest frequency of the full wave signal by a high pass filter in the frequency wave can be extracted; in the time domain, the new component phase wave with a component with wave the discontinuity of phase derivative signals can be discontinuous point out, also in the instantaneous frequency map for a jump point, which can be used to distinguish the various groups in the time domain wave.3. using finite difference method can effectively simulate the uniform formation conditions. In the simulation of uniform hard formations in this paper, the wave extraction method can get the characteristic frequency of the wave when the effective application of EMD, the decomposition of the IMF2, IMF3 can obtain the time-frequency characteristics of Stone wave. Quoted from the edge of time and frequency for different edge method. The source data of different distance and depth are analyzed. Time edge map can be seen as the source of hard rock from the change of peak Stone wave emergence time was positively related to linear increase; and the frequency in the edge graph due to the effect of pseudo Rayleigh wave frequency, irregular edge map performance. According to the situation: the soft stratum set different parameters, found in the same source, with changes in the formation of the longitudinal wave propagation velocity, wave frequency change, P-wave velocity increasing, the frequency is small. The author analyzed the reasons, probably because of the longitudinal wave velocity is large, the shorter the time to reach the receiver, so the frequency the frequency of the wave source is closer to the source, so the P-wave velocity increasing, the corresponding frequency difference method to simulate the situation of homogeneous formation in wells containing a horizontal crack is reduced using.4. finite difference. On fluid characteristics of different crack parameters. The fluid in the settings for the discovery of cracks when the water waves in through the cracks, the various components of the wave that were delayed, and the amplitude is greatly reduced. The wave was extracted, found that the longitudinal wave in through the cracks, the frequency decreases slightly however, frequency range is greatly reduced; when the fracture fluid is set to oil, sound in through the cracks, each component has the same time delay characteristics of wave, P-wave after oil crack, the frequency showed significantly reduced.5. selected actual logging data in eastern sag of Liaohe Oilfield, is selected with low angle fracture for reservoir or aquifer with lithology data analysis, mainly for time-frequency characteristics, longitudinal study found that relatively dense basalt, longitudinal aquifer basalt and basaltic rocks in the reservoir Time frequency characteristics, longitudinal wave to the relative delay, P-wave frequency attenuation in reservoir is more, while in the water relative attenuation degree smaller.6. we select the actual logging data in eastern sag of Liaohe Oilfield, the application of EMD decomposition and synchronous extrusion wavelet transform on the time-frequency characteristics of longitudinal waves in the wave group in tight formations and oil layer are analyzed, found after water acoustic wave attenuation, frequency and amplitude of high frequency waves are attenuated, Stone wave amplitude has great attenuation, low frequency of Stone wave amplitude attenuation of acoustic waves in small; most of the energy through the reservoir are concentrated in the acoustic wave and pseudo Rayleigh wave component, wave amplitude of high frequency components and delayed, and very serious.7. finally studied the reflection of Stone wave attenuation in the Stone wave, simulation of uniform In a horizontal crack containing strata, because the IMF3 component contains the main components of Stone wave, so the IMF3 component was extracted from the edge of time map can be seen as a reflection of Stone wave, namely the time in the edge graph inverted "V" shaped from a separate analysis of ripples. 1m source, you can see the accurate reflection Stone wave peak and frequency in the time-frequency diagram. The reflection of Stone wave can be used between the direct Stone wave distance can determine the location of cracks and development; to determine roughly the width of cracks according to the reflection of Stone wave energy, reflection energy the greater the crack width is greater.

【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631.81

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