基于波动方程偏移的地震数据地层成像

地层成像是对地下地层物性空间变化的近似反演,对于岩性油气藏和非常规油气藏的勘探开发具有重要价值。文中根据波动方程偏移的思想提出了一种有关反射体波阻抗相对扰动的地层成像方法。基于地震波运动学特征准确的地下介质光滑模型,应用地震波传播理论推导了基于反射体波阻抗相对扰动的地震数据线性正演表达式;然后结合线性反演理论,利用地震数据近似反演波阻抗相对扰动,构建了基于波动方程偏移的以波阻抗变化为主要目标的地震数据地层成像方法。在地层成像中,如果对波场做角度分解,则可得到地层成像的角度域共成像点道集,如果对波场不做角度分解,则可快捷地得到角度域平均的地层成像结果。对于声波方程描述的地震数据,利用该地层成像方法可获得地层的声波阻抗相对扰动成像;对于标量波方程描述的地震数据,利用该成像方法可获得地层的速度相对扰动成像。该地层成像方法与地震数据逆时偏移方法的计算过程相同、计算量相当,合成地震数据试验取得了理想的地层成像效果。

全井眼地层微成像仪测井图像失真的恢复技术

基于全井眼地层微成像仪(FMI)的仪器结构和测量原理,对井下仪器的运动状态进行分析,推导出描述仪器运动状态的微分方程,在此基础上对仪器的遇卡—解卡事件进行识别,然后利用卡尔曼滤波方法对井下仪器的运动状态作出最佳估计,得到原始采样数据的真实深度,最后利用Akima插值算法对极板数据进行重采样并生成成像图像。结果表明:经过校正后生成的FMI图像有效地消除了由于井下仪器的非匀速运动引起的拉伸、压缩、扭曲等图像失真现象,恢复了地层的原貌。该技术不仅适用于FMI成像测井,同样适用于其他进行了加速度测量的成像测井,具有推广应用价值。

地层微电阻率扫描成像测井及应用实例

地层微电阻率扫描成像测井使测井资料的应用变得更加直观,其解释成果拉近了与地层特征之间的“距离”。本文从地层微电阻率扫描成像测井的基本原理入手,以实例的形式分析了地层微电阻率扫捕成像测井在井旁构造分析、地应力方向确定、储集空间识别方面的的主要作用。

支持向量机与微电阻率成像测井识别火山岩岩性

针对火山岩储层,从岩石化学成分分类和岩石结构分类两个角度出发,提出了一种利用测井资料识别火山岩岩性的方法。基于取芯薄片鉴定资料获得对应井段的常规测井数据,利用统计学习理论中的支持向量机方法对其处理,得到地质上按岩石化学成分分类的火山岩岩性类别。建立地层微电阻率成像测井图像与不同结构火山岩岩性之间的对应关系,归纳出典型的微电阻率图像模式,从而得到地质上按岩石结构分类的火山岩岩性类别,结合上述两者结论确定最终岩性,实现了运用支持向量机算法处理常规测井资料与微电阻率图像模式相结合的火山岩岩性测井识别新方法。

成像测井技术在碳酸盐岩水平井中的应用

塔里木盆地北部地区碳酸盐岩油藏储层,非均质性较强,只依靠常规测井判断碳酸盐岩裂缝、溶孔、溶洞很困难.利用地层微电阻率扫描成像(FMI),对碳酸盐岩水平井储层进行定性分析、定量解释,并能准确识别出碳酸盐岩目的层裂缝的性质、大小、开度、溶蚀孔洞原生孔隙、次生孔隙的发育情况等.同时并利用测试、酸压资料验证了使用成像测井判断裂缝的有效性.

Optimizing data for electrical resistivity tomography in hardened sites through the ratio method

To reduce the shielding effect of hardened layers on electrical resistivity tomography,a ratio method based on the distortion correction principle and the isolation coefficient is proposed.The effects of the resistivity and thickness of hardened concrete layers on the detection of target objects are explored.Both numerical simulations and indoor tank tests indicate that when the ratio method is employed to correct the original collected data,the maximum allowable error for the isolation coefficient should not exceed 1%.Notably,when the ratio of hardened layer thickness to electrode spacing does not exceed 1,correction through this method significantly enhances the recognition capability of target objects.However,when the hardened layer thickness is greater than the electrode spacing by a factor of 2 or more,the ratio method cannot achieve satisfactory results.The case study of flood control engineering detection in the Zhangxi section of the Huangpen River in Dongzhi County demonstrates that the detection effect after correction by the ratio method is comparable to that for the adjacent unhardened pavement,and the influence of the hardened layer is obviously weakened,resulting in more reliable results.

Tomographic inversion for microseismic source parameters in mining

We propose a new method for inverting source function of microseismic event induced in mining. The observed data from microseismic monitoring during mining are represented by a wave equation in a spherical coordinate system and then the data are transformed from the time-space domain to the time-slowness domain based on tomographic principle, from whichwe can obtain the signals related to the source in the time-slowness domain. Through analyzing the relationship between the signal located at the maximum energy and the source function, we derive the tomographic equations to compute the source function from the signals and to calculate the effective radiated energy based on the source function. Moreover, we fit the real amplitude spectrum of the source function computed from the observed data into the co-2 model based on the least squares principle and determine the zero-frequency level spectrum and the corner frequency, finally, the source rupture radius of the event is calculated and The synthetic and field examples demonstrate that the proposed tomographic inversion methods are reliable and efficient

Joint inversion of P-wave velocity and Vp–Vs ratio: imaging the deep structure in NE Japan

A new inversion scheme is presented to obtain three-dimensional images of P-wave velocity（Vp） and P–S-wave velocity ratio（Vp/Vs） using P- and S-phase pairs, i.e., the same source–receiver pairs for the P- and S-wave arrival-time data. The S-wave velocity（Vs） was separately inverted using the S-phase arrival times. The earthquake hypocenters were simultaneously relocated in the joint inversion. The method considers the Vp/Vs anomaly as a model parameter in the inversion. The proposed method thus provides a more robust calculation of the Vp/Vs anomaly than the conventional method of dividing Vp by Vs. The method also takes into account the ray path difference between P- and S-waves, and hence yields a less biased Vp–Vs ratio than the method of inverting S–P-wave data for Vp and Vp/Vs anomalies under the assumption of identical P and S ray paths. The proposed method was used to image the crust and upper mantle in northeastern（NE） Japan taking advantage of a large number of high-quality arrival times of P- and S-wave source–receiver pairs. The inverted structures suggest that the subducting slab of the Pacific plate is an inclined zone of high-Vp and Vs anomalies with low Vp/Vs perturbation. The mantle wedge is characterized by low-Vp, low-Vs, and high-Vp/Vs anomalies at shallow depths beneath active volcanoes. These features are also observed at greater depths in the back-arc region. Although these features have been previously reported, the Vp/Vs anomaly pattern obtained in this study shows much less scatter and is much better correlated with the seismic velocity perturbation patterns than previous studies. The proposed method can be used, in conjunction with velocity anomaly patterns, to quantify thermal processes associated with plate subduction.

利用测井技术识别和探测裂缝

在测井新技术中用于裂缝识别与研究的主要是地层微电阻率扫描成像、声波成像和方位侧向成像等成像测井系列。常规测井技术与成像测井技术结合,不但可以识别裂缝,计算裂缝的几何参数,还能给出裂缝的有效性、发育程度等参数,进一步分析裂缝网络的横向展布情况。给出的实例说明了测井技术在探测裂缝方面的实用性。

Tomographic velocity inversion for ADCIGs in areas with a rugged surface

Pre-stack depth migration velocity analysis is one of the key techniques influencing image quality. As for areas with a rugged surface and complex subsurface, conventional prestack depth migration velocity analysis corrects the rugged surface to a known datum or designed surface velocity model on which to perform migration and update the velocity. We propose a rugged surface tomographic velocity inversion method based on angle-domain common image gathers by which the velocity field can be updated directly from the rugged surface without static correction for pre-stack data and improve inversion precision and efficiency. First, we introduce a method to acquire angle-domain common image gathers （ADCIGs） in rugged surface areas and then perform rugged surface tornographic velocity inversion. Tests with model and field data prove the method to be correct and effective.

东营凹陷北部陡坡带深层砂砾岩体岩性测井识别

东营凹陷北部陡坡带深层砂砾岩体岩性识别难度大,钻井取心、岩屑录井和井壁取心资料不能满足储层评价的需求。基于测井资料具有信息丰富、全井段采集的优点,探讨了利用岩心和岩心扫描图像刻度地层微电阻率扫描成像(FMI)测井,建立了利用FMI精细划分岩性和岩性组合的方法和模型;利用FMI划分岩性的成果刻度常规测井资料,提取不同岩性的常规测井曲线特征值,探讨了利用中子—密度孔隙度、声波—密度孔隙度交会和M—N值识别岩性的方法。结果表明,M和N值识别岩性效果较好,利用该方法识别的岩性与FMI识别的岩性具有较好的一致性,准确率达到79.99%,可满足测井评价的需要。

Location of high seismic activity zones and seismic hazard assessment in Zabrze Bielszowice coal mine using passive tomography

In the paper results of passive tomography calculations have been presented to assess rockburst hazard and locate high seismic activity zones in the vicinity of longwall 306 in Zabrze Bielszowice coal mine. The area of study was 1000 m in X direction by 900 m in Y direction. The zones of high values of P-wave propagation velocity have been found to correlate with the distribution of large seismic tremors.

FMI测井图像井壁复原方法优化及应用

地层微电阻率扫描成像测井(FMI)经数据处理后的彩色图像是测井解释与地质信息评价的重要依据,但由于FMI井下仪器生成的测井图像中存在一定规律性的空白带,这对测井解释人员利用FMI图像观察与提取地质信息有一定的影响。若FMI图像空白带较宽时,插值法等基于结构修复方法适用效果不佳,因此,采用基于纹理的图像修复方法,即Criminisi算法。传统的Criminisi算法在修复后期会出现错误匹配的情况,根据不同地层特征引入相应的梯度变量和优化修复置信度的改进方法,能够实现先修复边缘、结构更加完整,使井壁电成像图像复原的效果更佳。将复原图像和未复原图像进行地质非均质参数信息提取与对比,采用改进方法修复的图像更加符合实际地层地质情况,为FMI图像信息精确定量提取及应用于地质精细解释提供保障。

Seismic imaging of the middle and upper crust by double-difference tomography:the Haicheng earthquake (Ms 7.3) in Liaoning Province

The Haicheng earthquake （Ms 7.3） occurred in Liaoning Province （39°N-43°N, 120°E-126°E ）, China on February 4, 1975. The mortality rate was only 0.02% owing to the first timely and accurate prediction, although the area affected by the earthquake was 9200 km^2 and covered cities with a population density of 1000 p/km^2. In this study, the double- difference （DD） tomography method was used to obtain high-resolution three-dimensional （3D） P- and S-wave velocity （Vp and Vs） structures and Vp/Vs as well as the earthquake locations. Tomography results suggest that velocity structure at shallow depth coincides well with topography and sediment thickness. The earthquake locations form a northwest-striking zone associated with the Jinzhou（JZ） Fault and a northeast-striking zone associated with the Haichenghe-Dayanghe （HD） Fault, and suggest that the JZ Fault consists of three faults and the Ms 7.3 Haicheng earthquake originated at the intersection of the JZ and the Faults. Low- velocity zones （LVZs） with low Vp/Vs are observed at 15-20 km depth beneath the Haicheng （HC） region. We interpret the LVZs in the middle crust as regions of fluids, suggesting rock dehydration at high temperatures. The LVZs and low Vp/Vs in the upper crust are attributed to groundwater-filled cracks and pores. We believe that large crustal earthquakes in this area are caused by the combination of faulting and fluid movement in the middle crust.

FMI测井技术在川东北地区碳酸盐岩溶孔溶洞型储层评价中的应用

碳酸盐岩储层储集空间复杂多样,溶蚀孔洞发育且具有较强非均质性。根据实际岩心表面溶孔发育空间位置、均匀程度和溶孔直径,结合FMI特征,建立了FMI储层类型精细解释图版,并应用于非取心段储层类型的解释。川东北地区下三叠统飞仙关组、上二叠统长兴组的孔洞型储层可细分为三类:较连通型储层、局部连通型储层和孤立型储层。在储层类型解释基础上,结合FMI特征半定量地计算溶孔面孔率。通过取心井的验证,FMI测井技术可有效地应用于评价溶孔溶洞型碳酸盐岩储层的非均质性。

Passive seismic velocity tomography on longwall mining panel based on simultaneous iterative reconstructive technique (SIRT)

Mining operation, especially underground coal mining, always has the remarkable risks of ground control. Passive seismic velocity tomography based on simultaneous iterative reconstructive technique （SIRT） inversion is used to deduce the stress redistribution around the longwall mining panel. The mining-induced microseismic events were recorded by mounting an array of receivers on the surface, above the active panel. After processing and filtering the seismic data, the three-dimensional tomography images of the p-wave velocity variations by SIRT passive seismic velocity tomography were provided. To display the velocity changes on coal seam level and subsequently to infer the stress redistribution, these three-dimensional tomograms into the coal seam level were sliced. In addition, the boundary element method （BEM） was used to simulate the stress redistribution. The results show that the inferred stresses from the passive seismic tomograms are conformed to numerical models and theoretical concept of the stress redistribution around the longwall panel. In velocity tomograms, the main zones of the stress redistribution arotmd the panel, including front and side abutment pressures, and gob stress are obvious and also the movement of stress zones along the face advancement is evident. Moreover, the effect of the advance rate of the face on the stress redistribution is demonstrated in tomography images. The research result proves that the SIRT passive seismic velocity tomography has an ultimate potential for monitoring the changes of stress redistribution around the longwall mining panel continuously and subsequently to improve safety of mining operations.

Three-dimensional velocity structure and tectonic characteristics of earthquake area in Yibin

In this study,on the basis of absolute first-arrival times of 84756 P-and S-waves from 6085 earthquakes recorded at 56 fixed stations in Yibin and surrounding areas in China from January 2009 to January 2019,focal parameters and three-dimensional(3 D)body-wave high-resolution velocity structures at depths of 0–30 km were retrieved by double-difference tomography.Results show that there is a good correspondence between the spatial distribution of the relocated earthquakes and velocity structures,which were concentrated mainly in the high-velocity-anomaly region or edge of high-velocity region.Velocity structure of P-and S-waves in the Yibin area clearly shows lateral inhomogeneity.The distribution characteristics of the P-and S-waves near the surface are closely related to the geomorphology and geologic structure.The low-velocity anomaly appears at the depth of 15–25 km,which is affected by the lower crust current.The Junlian–Gongxian and Gongxian–Changning earthquake areas,which are the two most earthquake-prone areas in the Yibin region,clearly differ in earthquake distribution and tectonic characteristics.We analyzed the structural characteristics of the Junlian–Gongxian and Gongxian–Changning earthquake areas on the basis of the 3 D bodywave velocity structures in the Yibin region.We found that although most seismicity in the Yibin area is caused by fluid injection,the spatial position of seismicity is controlled by the velocity structures of the middle and upper crust and local geologic structure.Fine-scale 3 D velocity structures in the Yibin area provide important local reference information for further understanding the crustal medium,seismogenic structure,and seismicity.

Research on the 3-D Seismic Structures in Qinghai-Xizang Plateau

Based on the recording data from the analogue and broadband digital seismic stations in and around Qinghai-Xizang (Tibet) Plateau, the three dimensional (3-D) seismic velocity structures in Qinghai-Xizang Plateau were obtained by using the regional body wave tomography and surface wave tomography. The results from these two tomography methods have similar characteristics for P- and S-wave velocity structures in crust and upper mantle. They show that there are remarkable low velocity zones in the upper crust of Lhasa block in the southern Qinghai-Xizang Plateau and the lower crust and upper mantle of Qiangtang block in the northern Qinghai-Xizang Plateau. These phenomena may be related to the different steps of collision process in southern and northern Qinghai-Xizang Plateau.

Physical modeling of failure process of the excavation in horizontal strata based on IR thermography

In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.