基于成像域射线束建模的剩余静校正方法研究及应用

由信噪比极低的资料生成的剩余静校正模型,其信噪比通常也较低,导致剩余静校正效果不理想,因此提高模型的信噪比,在提高资料处理品质中有着极其重要的意义.文章提出了一种基于成像域射线束建模的剩余静校正的方法.该方法是采用成像域射线束建模对数据进行分解和重构,并且根据不同的分解级数和分解尺度,分解和重构成不同成分的数据,该方法在重构的过程中加入倾角场的约束,能有效保护高陡构造.成像域射线束建模得到的第一级分量为数据的主要成分,构造保真,信噪比高,把该分量作为外部模型,进行外部模型剩余静校正.把本文方法在低信噪比资料进行应用,提高低信噪比资料的剩余静校正效果,有效的改善了资料处理成果的品质.     

川东南复杂山地灰岩区静校正技术综合应用研究

复杂山地灰岩出露区勘探存在严重的静校正问题,解决静校正问题难度较大,由于静校正问题的存在会降低地震资料的垂向分辨率、出现假构造、影响速度分析,严重影响地震资料成像质量,降低勘探成功率.为解决复杂山地灰岩区勘探存在的静校正问题,本文研究了高程静校正、折射静校正和初至层析静校正,分析对比不同方法的优缺点和应用效果,在此基础上提出并研究融合静校正技术,在本研究区中,该方法是采用折射静校正和初至层析静校正量的优势区域进行融合,充分发挥不同方法的优点和适应性,较好的解决一次静校正;针对剩余静校正问题,提出了基于反射波剩余静校正、成像域射线束剩余静校正和速度建模的循环迭代综合剩余静校正处理技术,分步逐级迭代解决剩余静校正问题,该方法集成了反射波剩余静校正、成像域射线束剩余静校正的优点,明显提高地震剖面的细节成像质量.通过本文研究,建立了一套针对复杂山地灰岩区低信噪比资料的静校正处理技术序列并形成一套处理流程,在川东南复杂山地灰岩区低信噪比数据处理中,验证了该技术序列的可行性,取得比较好的效果.     

抛物线Radon变换方法在压制地震多次波中的应用

多次波的存在会降低地震资料的信噪比,影响地震资料处理效果和后续的地质解释精度,压制多次波干扰是地震资料处理中的一个重要环节。利用有限差分方法正演模拟几个典型地质模型的地震波场,之后进行动校正,再通过抛物线Radon变换方法把t-x域一次反射波和多次波变换到τ-q域,由于存在速度的差异,Radon域记录中的一次反射波和多次波的能量互相分开,在Radon域对多次波的能量切除,保留反射波的有效信息,达到压制多次波的效果,提高资料的信噪比。通过对实际地震数据进行抛物线Radon变换结果也进一步验证了该方法在压制多次波中的应用效果。      

西部山地复杂地震资料处理技术研究

在山地地震资料处理中,由于地震条件和地质条件复杂,使得资料的静校正问题严重,资料的信噪比偏低.通过采用配套的静校正技术和串联叠前去噪技术,较好地解决了这两个问题.     

基于西部某工区低信噪比地震资料处理效果分析

为了实现资源的接替,我国的资源勘探逐步进入西部领域。由于激发和接受的条件较差,给野外采集工作带来了新的困难,导致采集到的原始野外资料信噪比较低,针对工区低信噪比地震资料反射信号较弱,声波面波干扰严重等特点。本文首先深入分析了低信噪比资料的特点,在此基础上结合适合低信噪比地震资料的处理方法流程,优选二维的F-K滤波对干扰波进行压制,处理前后进行对比,通过对比分析它们的适应性,得出一个适合于研究区低信噪比地震资料的滤波方法。     

鄂尔多斯盆地北部低信噪比资料的高分辨率处理

鄂尔多斯盆地北部地区地震地质条件复杂,造成原始地震资料信噪比低,分辨率低,前期的地震资料储层与含气性预测的成果达不到目前勘探开发的要求.本文针对鄂尔多斯盆地北部低信噪比地震资料的特点,提出了一套适合本区的高分辨率处理方法,通过解决静校正和去噪问题,应用反褶积、精细速度分析以及高精度动校正和叠加等处理技术,在保证信噪比的前提下,提高了地震资料的分辨率.     

古龙断陷深层火山岩地震资料成像方法及应用研究

松辽盆地北部古龙断陷的地震地质条件复杂,三维地震资料品质较差,所以提高地震资料的信噪比和断陷期地层的成像精度是当前地震资料处理的研究重点.在提高地震资料信噪比方面,本文进行了十字交叉排列面波压制技术、压制规则干扰的减去法多次波压制技术和基于菲涅耳带原理的超面元技术的研究,这些技术的有效应用,对保护深层有效波的低频信号、...     

一种新静校正方法及其在黄土塬地震资料的应用

针对鄂尔多斯盆地西南部黄土塬地震资料严重的静校正问题,本文提出利用层析反演静校正,折射波静校正方法分别计算静校正量,按照地表一致性原则,将两种方法计算的炮点,检波点校正量各自分解为高频校正量和低频校正量,然后进行最优化组合,从而获得全新的炮点和检波点静校正量.鄂尔多斯盆地西南部黄土塬地区地震资料实际应用表明,应用本文方法计算的静校正量的地震剖面与单独应用层析静校正量或折射静校正量的地震剖面相比,其层位同相轴连续性和信噪比得到了很大的改善,从而证明本方法的正确可靠性.同时表明,本方法能够很好的解决本区静校正问题.     

一种优化预测滤波压制随机噪声的方法

针对低信噪比地震资料中的随机噪声干扰,提出了一种优化的预测滤波方法.通过对AR模型数学表达式进行改写,然后引入反褶积代价函数,最后推导得到压制随机噪声的递归算法.该算法实现了单道压制随机噪声,保护了有效信号的细节部分,比基于常规最小二乘代价函数的滤波算法收敛更快.通过模拟和实际地震资料验证表明,该方法能较好地压制低信噪比资料中的随机噪声干扰,同时能较好地保护有效地震信号.     

保幅低频面波压制方法与应用

面波是陆地地震勘探中的一种强能量规则干扰,面波的存在对地震数据成像有很大影响,因此需要对面波予以压制.常规面波压制方法只考虑面波的强能量特性,很容易损伤面波频带内的有效信号,难以满足地震资料保幅处理的要求.在传统方法的基础上,本文提出低频弱信号保护的面波压制方法,该方法在有效地消除面波干扰的同时,最大程度的减少了低频有效信息的损失,提高地震资料的信噪比和保幅性,松辽盆地北部西部斜坡地区实际地震资料的处理表明,该方法是一种有效的相对保幅的面波压制方法,可为岩性油气藏勘探提供重要的基础数据,具有很强的实用性.     

若尔盖盆地-西秦岭造山带结合部位深反射资料的静校正和去噪技术

深地震反射剖面技术是探测岩石圈精细结构的有效手段.通常情况下工区地质情况复杂,尤其在盆山结合部位,地表地形起伏大,地下构造复杂,其深地震反射资料具有低信噪比、干扰强、构造复杂等特点,给后续处理和解释造成很大困难,因此获得真实的叠加剖面是地质解释的前提和基础.复杂地区低信噪比深地震反射资料处理的关键是做好静校正和去噪工作.本文以若尔盖盆地－西秦岭造山带接合部位深地震反射资料作为例,通过方法试验和参数测试,找到适合该工区的静校正方法和去噪技术,得到较好的处理结果,为揭示若尔盖盆地－西秦岭造山带结合部位的细结构提供了可靠的依据.     

基于偏移成像道集的剩余静校正方法

针对陆上地震资料处理的静校正问题,提出了一种基于偏移成像道集的剩余静校正方法.与传统的由动校正后的CMP道集中拾取剩余时差不同,本文基于偏移成像道集求取剩余时差,避免了复杂情况下同相轴归位不准确导致的剩余时差拾取误差.通过生成随炮点和检波点位置变化的偏移道集,实现了由偏移道集中直接拾取炮、检点的地表一致性剩余时差;该炮、检点偏移道集只在指定的局部时窗生成,并不增加大的计算量.二维和三维实际数据测试表明了该方法的有效性和实用性.     

用优化聚束滤波方法消除低信噪比地震资料中的多次波

针对常规方法如f k,Radon变换不能很好解决的消除低信噪比地震勘探资料的多次波问题,本文提出了优化聚束滤波方法,采用具有静态权的自适应聚束滤波器,并调整聚束滤波器设计的约束准则,去除低信噪比复杂实际资料中的多次波．实际资料处理结果表明,优化聚束滤波方法改善了最小方差无偏聚束滤波方法不能较好地处理低覆盖低信噪资料处理的局限性,在实际处理中计算量增加不大．     

Time-lapse processing of 2D seismic profiles with testing of static correction methods at the CO2 injection site Ketzin (Germany)

The Ketzin project provides an experimental pilot test site for the geological storage of CO₂. Seismic monitoring of the Ketzin site comprises 2D and 3D time-lapse experiments with baseline experiments in 2005. The first repeat 2D survey was acquired in 2009 after 22 kt of CO₂ had been injected into the Stuttgart Formation at approximately 630 m depth. Main objectives of the 2D seismic surveys were the imaging of geological structures, detection of injected CO₂, and comparison with the 3D surveys. Time-lapse processing highlighted the importance of detailed static corrections to account for travel time delays, which are attributed to different near-surface velocities during the survey periods. Compensation for these delays has been performed using both pre-stack static corrections and post-stack static corrections. The pre-stack method decomposes the travel time delays of baseline and repeat datasets in a surface consistent manner, while the latter cross-aligns baseline and repeat stacked sections along a reference horizon.Application of the static corrections improves the S/N ratio of the time-lapse sections significantly. Based on our results, it is recommended to apply a combination of both corrections when time-lapse processing faces considerable near-surface velocity changes. Processing of the datasets demonstrates that the decomposed solution of the pre-stack static corrections can be used for interpretation of changes in near-surface velocities. In particular, the long-wavelength part of the solution indicates an increase in soil moisture or a shallower groundwater table in the repeat survey.Comparison with the processing results of 2D and 3D surveys shows that both image the subsurface, but with local variations which are mainly associated to differences in the acquisition geometry and source types used. Interpretation of baseline and repeat stacks shows that no CO₂ related time-lapse signature is observable where the 2D lines allow monitoring of the reservoir. This finding is consistent with the time-lapse results of the 3D surveys, which show an increase in reflection amplitude centered around the injection well. To further investigate any potential CO₂ signature, an amplitude versus offset (AVO) analysis was performed. The time-lapse analysis of the AVO does not indicate the presence of CO₂, as expected, but shows signs of a pressure response in the repeat data.     

胜利滩海地震勘探采集

胜利滩海地区地理地质条件特殊，勘探程度低、难度大。通过对滩海及极浅海地区采集方法的研究，在改进采集设备的同时，进一步完善了野外观测系统设计，总结了各种激发因素和接收因素，形成一套完整合理的有利于滩海及极浅海地区地震勘探方法，使地震资料的信噪比和分辨率得到了很大提高，从而为地下构造形态研究、油藏描述提供了可靠的基础资料。     

CRS strategies for solving severe static and imaging issues in seismic data from Saudi Arabia

Static shifts from near‐surface inhomogeneities very often represent the key problem in the processing of seismic data from arid regions. In this case study, the deep bottom fill of a wadi strongly degrades the image quality of a 2D seismic data set. The resulting static and dynamic problems are solved by both conventional and common‐reflection‐surface (CRS) processing. A straightforward approach derives conventional refraction statics from picked first breaks and then goes through several iterations of manual velocity picking and residual statics calculation. The surface‐induced static and dynamic inhomogeneities, however, are not completely solved by these conventional methods. In CRS processing, the local adaptation of the CRS stacking parameters results in very detailed dynamic corrections. They resolve the local inhomogeneities that were not detected by manual picking of stacking velocities and largely compensate for the surface‐induced deterioration in the stack. The subsequent CRS residual statics calculations benefit greatly from the large CRS stacking fold which increases the numbers of estimates for single static shifts. This improves the surface‐consistent averaging of static shifts and the convergence of the static solution which removes the remaining static shifts in the 2D seismic data. The large CRS stacking fold also increases the signal‐to‐noise ratio in the final CRS stack.     

WEIGHTED STACKING OF SEISMIC DATA USING AMPLITUDE-DECAY RATES AND NOISE AMPLITUDES1

The signal-to-noise (S/N) ratio of seismic reflection data can be significantly enhanced by stacking. However, stacking using the arithmetic mean (straight stacking) does not maximize the S/N ratio of the stack if there are trace-to-trace variations in the S/N ratio. In this case, the S/N ratio of the stack is maximized by weighting each trace by its signal amplitude divided by its noise power, provided the noise is stationary. We estimate these optimum weights using two criteria: the amplitude-decay rate and the measured noise amplitude for each trace. The amplitude-decay rates are measured relative to the median amplitude-decay rate as a function of midpoint and offset. The noise amplitudes are measured using the data before the first seismic arrivals or at late record times. The optimum stacking weights are estimated from these two quantities using an empirical equation. Tests with synthetic data show that, even after noisy-trace editing, the S/N ratio of the weighted stack can be more than 10 dB greater than the S/N ratio of the straight stack, but only a few decibels more than the S/N ratio of the trace equalized stack. When the S/N ratio is close to 0 dB, a difference of 4 dB is clearly visible to the eye, but a difference of 1 dB or less is not visible. In many cases the S/N ratio of the trace-equalized stack is only a few decibels less than that of the optimum stack, so there is little to be gained from weighted stacking. However, when noisy-trace editing is omitted, the S/N ratio of the weighted stack can be more than 10 dB greater than that of the trace-equalized stack. Tests using field data show that the results from straight stacking, trace-equalized stacking, and weighted stacking are often indistinguishable, but weighted stacking can yield slight improvements on isolated portions of the data.     

复杂山区初至波层析反演静校正

提高静校正精度是取得复杂山区良好地震成像的一个重要条件.而建立在水平折射面假设基础之上折射波静校正方法,无论是假设前提还是实际应用效果,都不适应于地表剧烈起伏,速度纵、横向变化大的复杂区.为此本文提出使用初至波层析反演静校正方法,即利用地震记录中初至旅行时反演出表层速度模型,计算出炮点和检波点的静校正量.通过正演模拟数据和实际资料的验证,很好的解决了复杂地表引起的静校正问题.