Near-surface absorption compensation technology and its application in the Daqing Oilfields

High-frequency seismic data components can be seriously attenuated during seismic wave propagation in unconsolidated （low-velocity） layers, resulting in reduced seismic resolution and signal-to-noise （S/N） ratio. In this paper, first, based on Wiener filter theory, inverse filter calculations for near-surface absorption attenuation compensation were accomplished by analysis of the direct wave spectral components from different distances near the surface. The direct waves were generated by detonators in uphole shots and were acquired by receivers on the surface. The spatially varying inverse filters were designed to compensate for the frequency attenuation of 3D pre-stack CRG （common receiver-gather） data. After applying the filter to CRG data, the high frequency components were compensated with the low frequencies maintained. The seismic resolution and S/N ratio are enhanced and match better with synthetic seismograms and better meet the needs of geological interpretation.

High angle prestack depth migration with absorption compensation

The absorption effect of actual subsurface media can weaken wavefield energy, decrease the dominating frequency, and further lead to reduced resolution. In migration, some actions can be taken to compensate for the absorption effect and enhance the resolution. In this paper, we derive a one-way wave equation with an attenuation term based on the time- space domain high angle one-way wave equation. A complicated geological model is then designed and synthetic shot gathers are simulated with acoustic wave equations without and with an absorbing term. The derived one-way wave equation is applied to the migration of the synthetic gathers without and with attenuation compensation for the simulated shot gathers. Three migration profiles are obtained. The first and second profiles are from the shot gathers without and with attenuation using the migration method without compensation, the third one is from the shot gathers with attenuation using the migration method with compensation. The first and third profiles are almost the same, and the second profile is different from the others below the absorptive layers. The amplitudes of the interfaces below the absorptive layers are weak because of their absorption. This method is also applied to field data. It is concluded from the migration examples that the migration method discussed in this paper is feasible.

A method for absorption compensation based on adaptive molecular decomposition

In this paper,we present a new method for seismic stratigraphic absorption compensation based on the adaptive molecular decomposition.Using this method,we can remove most of the effects resulting from wavelets truncation and interference which usually exist in the common time-frequency absorption compensation method.Based on the assumption that the amplitude spectrum of the source wavelet is smooth,we first construct a set of adaptive Gabor frames based on the time-variant properties of the seismic signal to transform the signal into the time-frequency domain and then extract the slowly varying component（the wavelet＇s time-varying amplitude spectrum） in each window in the timefrequency domain.Then we invert the absorption compensation filter parameters with an objective function defined using the correlation coefficients in each window to get the corresponding compensation filters.Finally,we use these filters to compensate the timefrequency spectrum in each window and then transform the time-frequency spectrum to the time domain to obtain the absorption-compensated signal.By using adaptive molecular decomposition,this method can adapt to isolated and overlapped seismic signals from the complex layers in the inhomogeneous viscoelastic medium.The viability of the method is verified by synthetic and real data sets.

Charge compensation and capacity fading in LiCoO2 at high voltage investigated by soft x-ray absorption spectroscopy

In order to obtain an in-depth insight into the mechanism of charge compensation and capacity fading in LiCoO2, the evolution of electronic structure of LiCoO2 at different cutoff voltages and after different cycles are studied by soft x-ray absorption spectroscopy in total electron（TEY） and fluorescence（TFY） detection modes, which provide surface and bulk information, respectively. The spectra of Co L2,3-edge indicate that Co contributes to charge compensation below 4.4 V.Combining with the spectra of O K-edge, it manifests that only O contributes to electron compensation above 4.4 V with the formation of local O 2 p holes both on the surface and in the bulk, where the surficial O evolves more remarkably. The evolution of the O 2 p holes gives an explanation to the origin of O2^-or even O2. A comparison between the TEY and TFY of O K-edge spectra of LiCoO2 cycled in a range from 3 V to 4.6 V indicates both the structural change in the bulk and aggregation of lithium salts on the electrode surface are responsible for the capacity fading. However, the latter is found to play a more important role after many cycles.

Carbon decorated Li_(3)V_(2)(PO_(4))_(3) for high-rate lithium-ion batteries:Electrochemical performance and charge compensation mechanism

Fast charging and high-power delivering batteries are highly demanded in mobile electronics,electric vehicles and grid energy storage,but there are full of challenges.The star-material Li_(3)V_(2)(PO_(4))_(3) is demonstrated as a promising high-rate cathode material meeting the above requirements.Herein,we report the carbon decorated Li_(3)V_(2)(PO_(4))_(3) (LVP/C) cathode prepared via a facile method,which displays a remarkable high-rate capability and long-term cycling performance.Briefly,the prepared LVP/C delivers a high discharge capacity of 122 mAh g^(-1)(-93% of the theoretical capacity) at a high rate up to 20 C and a superior capacity retention of 87.1% after 1000 cycles.Importantly,by applying a combination of X-ray absorption spectroscopy and full-range mapping of resonant inelastic X-ray scattering,we clearly elucidate the structural and chemical evolutions of LVP upon various potentials and cycle numbers.We show unambiguous spectroscopic evidences that the evolution of the hybridization strength between V and O in LVP/C as a consequence of lithiation/delithiation is highly reversible both in the bulk and on the surface during the discharge-charge processes even over extended cycles,which should be responsible for the remarkable electrochemical performance of LVP/C.Our present study provides not only an effective synthesis strategy but also deeper insights into the surface and bulk electrochemical reaction mechanism of LVP,which should be beneficial for the further design of high-performance LVP electrode materials.

近地表连续介质区Q值调查应用研究

为了提高地震资料的分辨率,对原始资料进行吸收补偿,需要提高近地表Q模型的精度。针对结构疏松、速度变化快且风化层厚度较大的连续介质近地表对地震波吸收衰减严重的问题,开展了品质因子调查、近地表Q建模等方面研究工作。结果表明:1)井中激发、地表和井底同时接收的双井微测井调查方式,可提高品质因子的精度;2)涵盖了不同风化层速度、厚度且样点数据充分的近地表Q值调查结果保证了Q-v经验公式的统计规律;3)微测井调查的高精度近地表模型为构建层状近地表Q模型奠定了基础;4)连续介质近地表Q模型更加真实地反映了实际近地表Q值的分布规律。以上成果认识,对近地表为连续介质的沙漠、黄土塬等工区提高分辨率地震勘探采集具有一定指导意义。

黄土塬地区双井微测井近地表Q模型的求取及应用

针对鄂尔多斯盆地黄土塬地区地震资料分辨率低、子波一致性差的问题,提出一种近地表Q模型求取方法,进而开展地震数据近地表Q吸收补偿处理。以往通常采用微测井资料求取Q值进而插值获得全工区Q场,本文在前人基础上采用双井微测井资料计算井点位置的Q值和近地表速度值,通过最小二乘法拟合近地表速度与Q的区域关系函数,利用基础静校正初至波层析反演的近地表速度场,通过区域关系函数得到本区近地表的Q场,从而实现以微测井位置的Q值求得全工区近地表Q场的目的,进而开展叠前道集近地表Q吸收补偿处理。鄂尔多斯盆地黄土塬“双复杂”地震资料应用结果表明,利用本方法反演Q场开展近地表Q吸收补偿处理,能够有效提高地震资料的子波一致性,拓宽频带,改善井震匹配关系,消除近地表对地震子波的影响。

基于TDLAS甲烷检测系统压强补偿的研究

基于可调谐半导体激光吸收光谱技术,在1653 nm波段结合波长调制光谱吸收技术(WMS),使用光程为14 m长的Herriott型多光程池组成了气体检测系统,并通过此系统在常温常压的条件下,对CH4进行测量实验,其中拟合决定系数为0.998.为了分析压强对二次谐波信号的影响,通过此系统测量了不同压强对应的二次谐波信号,将二次谐波信号幅值与压强进行线性拟合,线性关系良好.通过二次谐波过零点间距的解析式计算得到被测气体压强,并通过拟合公式实现无需压力传感装置的压强补偿功能,在负压情景下的工业测量具有较广泛的应用前景.

频谱一致性Q因子反演方法

地层品质因子Q能够定量表征地层吸收对地震信号的衰减效应,对高分辨率地震数据处理和油气检测均具有重要作用。针对现有Q因子估算方法抗噪性弱、稳定性差等问题,提出了一种基于频谱一致性准则的Q因子反演方法。该方法基于粘弹性介质地震波传播理论,将不同时间接收的地震信号反向传播到某一位置,基于反向传播之后频谱特征的一致性对Q因子进行反演。不同于谱比法和质心频移法,该方法不是基于对数谱斜率和质心频移等地震频谱的某个特定属性,而是基于地震频谱在整体特征上的一致性对Q因子进行反演和估算,其反演结果的稳定性和抗噪性更好。理论模型和实际数据的实验结果表明,采用该方法能够得到更加可靠的Q模型,其补偿结果较好地恢复了高分辨率地震数据的反射特征。

信号自适应识别吸收补偿方法

地下介质的吸收衰减效应严重降低了地震信号的探测深度,限制了高分辨率地震勘探的发展。反Q滤波技术是补偿地层吸收衰减、提高地震分辨率的重要手段。然而,传统的反Q滤波方法本身并不具备信号识别能力,在补偿地震信号的同时会放大噪声干扰。为此,文中提出一种信号自适应识别的多道吸收补偿方法,其核心思想是利用地震信号的空间构造特征提升吸收补偿算法的稳定性和精度。该方法主要实施流程包括四步:首先,利用空间预测算子对反射信号的空间构造特征进行数学表达;再根据信号预测算子构造空间反射结构约束项;然后,将反射结构约束项加入多道吸收补偿目标函数,得到吸收补偿反演系统;最后,求解多道反演目标函数,得到吸收补偿结果。模型数据测试和实际资料应用结果表明:所提方法不仅能提高地震资料的分辨率,还可保护补偿结果的空间构造特征和信噪比,具有较强的稳定性和一定的实用性。

沙漠区地震数据高分辨率处理关键方法及其在尼日尔Agedem地区的应用

针对表层沙丘对地震反射波的高频能量吸收衰减严重会导致沙漠区地震资料存在分辨率低、能量弱、频带窄等问题,提出了一种结合微测井约束的近地表叠前Q补偿、叠前深度Q偏移及基于井约束的压缩感知叠后拓频等3种方法的地震资料处理方法,并将该方法在尼日尔Agedem地区进行了测试。研究结果表明:①经微测井约束的Q补偿法处理后,尼日尔Agedem地区地震资料信噪比和分辨率均更高,同相轴更光滑连续,有效信息能量增强,细小结构刻画得更为清晰;频带宽度从35 Hz拓宽至约70 Hz,主频从30 Hz提升至约45 Hz。②Q叠前深度偏移消除了地震波传播过程中由于介质非弹性因素和地层吸收所引起的衰减与频散,保证了成像精度。③基于井约束的压缩感知叠后拓频方法处理后的结果较无井约束拓频处理与井合成记录更为匹配,具有更好的保真性,进一步提升了弱信号能量,恢复了严重吸收衰减效应所造成的能量损失,尼日尔Agedem地区20~40 ms层位位置更准确,在无井约束处理后180 ms处出现的层位假象问题得到解决。④该联合方法在尼日尔Agedem地区的应用取得了较好的效果,处理后的地震资料断层结构清晰、断面波干脆、小断层错段明显容易识别;结合测井数据对DB1井进行井-震标定后,全井段相关系数大于0.92。

复杂地表条件下地震资料一致性处理方法研究与应用

鄂尔多斯盆地东部地处黄土塬区,沟壑纵横、地形起伏非常大,受复杂地表条件及近地表结构等因素影响,原始地震记录的振幅、频率及相位在不同区域存在明显差异,这些差异与地下地质信息无关,容易导致解释陷入误区。因此,急需根据该区地震资料特点进行一致性处理方法研究,以提高资料保真度。在总结当前一致性处理方法的基础上,本文建立了复杂地表条件下新的地震资料一致性处理技术流程。在创新地表一致性振幅补偿思路的基础上,首次应用双域近地表Q吸收补偿技术,拓宽频带的同时,提高沟—塬连接线资料振幅、频率一致性;应用地表一致性俞氏子波反褶积,实现低频噪声的衰减及有效信号频带的拓宽,提高地震资料信噪比、分辨率的同时,进一步提高资料子波一致性。实际资料应用证实了该方法的可行性和有效性,具有良好的推广应用价值。

川中地区北斜坡二叠系碳酸盐岩储层弱反射信号处理技术

四川盆地碳酸盐岩储层埋藏深、缝洞发育、非均质性强,储层与上下围岩的波阻抗差异小,难以形成强的反射界面,其内幕表现为断续、弱能量的地震反射特征,致使储层的地震响应更加微弱。针对原始地震资料反射信号弱、频率衰减严重的特点,以信号保真去噪、弱反射信号的振幅、频率恢复和叠后处理技术为研究重点,开展了深层碳酸盐岩弱反射信号处理技术攻关研究。研究结果表明:①采用保真组合去噪技术较好地保护了二叠系储层弱反射信号;②采用地震处理获得的层速度,按照经验公式计算地层Q体数据并进行波动方程Q吸收补偿,对储层弱反射损失信号进行了较好的恢复;③偏移后采用优势道集叠加,并对新叠加数据体进行子波整形保真拓频,凸显了二叠系储层的地震响应。通过在射洪、西充等地区二叠系茅口组储层预测中的应用,获得了89%的储层预测成功率。

一种频域吸收衰减补偿方法

针对地震信号的吸收衰减补偿问题,在重新建立吸收系数和Q值关系的基础上,提出了一种基于反Q补 偿的分时窗频域吸收衰减补偿方法。首先,逐道抽取地震信号,从浅层到深层选取不同长度的时窗进行傅里叶 变换;然后从非均匀粘弹介质波动方程出发,导出更加准确的吸收系数与Q值的关系,并应用于频域吸收衰减补 偿中;最后将处理得到的频谱反傅里叶变换回时间域重构地震信号。将该方法应用于松辽盆地某地区的叠前和 叠后地震资料的吸收衰减补偿,取得了很好的效果,地震资料的信噪比和分辨率得到了提高。

近地表高频补偿技术在三维地震勘探中的应用研究

近地表的滤波作用不仅会引起地震波高频成分的快速衰减,还会引起地震子波相位的畸变,在高分辨率地震资料处理中,必须对这些由近地表引起的衰减和频散进行补偿.文中研究了近地表吸收规律,应用微测井资料求出了表层的吸收衰减因子,补偿了近地表高频成分,给出了针对三维地震资料的近地表高频补偿方法,对大庆齐家北工区的地震资料进行了实际应用,同时还应用属性分析技术对应用效果进行了分析评价,结果表明,该方法是可行的.

DOAS方法在线测量污染气体浓度的温度与非线性补偿

差分吸收光谱法(DOAS)应用于固定污染源烟气排放监测时,烟气温度及气体的非线性吸收对准确测量气体浓度影响较大,必须对温度及非线性吸收的影响进行修正。文中分别提出了新的温度补偿及新的非线性补偿方法,即将不同温度下气体的分子数密度与20℃下气体的分子数密度之比与温度的对应关系拟合出温度补偿函数,将气体实际浓度所对应的分子数密度与反演结果所对应的分子数密度之比与反演结果之间的对应关系拟合成非线性补偿函数,利用这两个补偿函数对浓度反演结果进行补偿。对14914mg/m^3的SO_2气体在70～170℃温度范围内的实验研究结果表明,新的温度补偿及非线性补偿函数能很好的补偿温度及非线性的影响,具有较高的气体浓度反演精度。

基于广义S变换的吸收衰减补偿方法

探讨了利用广义 S 变换代替短时 Fourier 变换或连续小波变换,进行吸收衰减补偿的方法。对短时 Fou- tier 变换、连续小波变换、S 变换和广义 S 变换进行了分析和比较,给出了基于广义 S 变换的吸收衰减补偿方法。该方法的实现步骤是：①用广义 S 变换对高信噪比的叠加地震信号逐道进行时频分析；②在每个时间点,根据地层吸收特点提取各个频率的能量吸收衰减因子；③用加权方法对每个时间所对应的各个频率的广义 S 变换系数进行补偿,使各个频率在不同时间的能量相同；④将所有时间各个频率加权补偿的结果重构回地震记录,实现对地层吸收的补偿。模拟结果表明,广义 S 变换时频分析方法能够提高信号时频分布的分辨率。对实际二维地震数据的试算结果表明,基于广义 S 变换的吸收衰减补偿方法能较好地对地层吸收进行补偿,提高地震资料的分辨率,改善地震资料的品质。

近地表疏松介质吸收补偿的数学模拟研究

为有效提高地震资料的分辨率,定量研究地震波在疏松介质中的吸收效应及补偿条件尤为重要。根据塔里木盆地针对性施工的微测井原始资料,采用频谱比法计算表层品质因子的分布规律;应用地震波在粘弹性介质中的传播机制,符合线性吸收机制原理,采用相移法在频率-空间域对地震波在疏松介质中的传播,进行正演及吸收衰减补偿的数学模拟。结果表明:疏松介质对地震波的高频吸收衰减,只有在特定的表层地震地质条件下,才能通过后续补偿处理得以恢复,给出了完全补偿这种吸收衰减效应的条件,为沙漠地区地震资料分辨率的合理上限提供了理论模拟数据。

塔里木沙漠区地震数据品质与沙层Q吸收

45(1):28～34摘要结合塔里木沙漠区勘探地震数据、沙层Q吸收调查数据以及Q吸收理论模拟,本文对造成该区地震数据品质与地形相关性的主要原因、沙层Q吸收对地震数据的作用以及针对沙层的Q值估算和Q吸收补偿等问题进行较为深入的分析。分析结果表明:沙层Q吸收不是造成该区地震数据品质与地形相关性的主要原因;现有的Q值估算方法,在针对沙层的Q值估算中面临很强的干扰;Q吸收补偿只能在一定程度上减小与地形相关性的地震数据品质差异。

基于差分吸收检测技术的非色散红外SF_6传感器

基于非色散红外吸收原理,以电调制红外光源、采样气室和双元红外探测器组成的红外传感模块为核心,利用差分吸收检测技术设计了一种小型化高性能的SF_6气体传感器。利用标准气体进行浓度标定,拟合了SF_6气体浓度与电压关系曲线,实现了对SF_6气体浓度的准确检测。根据传感器检测误差随环境温度变化的规律,系统研究了温度补偿方法,有效提高了传感器在不同温度下的检测精度。实验结果表明,该传感器系统在环境温度10℃~40℃、气体浓度0~2 500×10^(-6)范围内的检测精度小于±50×10^(-6),分辨率为1×10^(-6),系统响应时间小于5 s,具有良好的重复性和稳定性。