Full wave seismic exploration technology

Reflected wave seismology has the following defects:the acquisition design is based on the assumption of layered media,the signal processing suppresses weak signals such as diffracted wave and scattered wave,and the seismic wave band after the image processing is narrow.They limit the full utilization of broadband raw data.The concept of full wave seismic exploration is redefined based on the idea of balanced utilization of reflected wave,diffracted wave and scattered wave information,its characteristics and adaptive conditions are clarified.A set of key technologies suitable for full wave seismic exploration are put forward.During seismic acquisition period,it is necessary to adopt multi geometry,i.e.embed small bin,small offset and small channel interval data in conventional geometry.By discretizing of common midpoint(CMP)gathers,small offset with high coverage,the weak signals such as diffracted wave and scattered wave in the raw seismic data can be enhanced.During seismic processing,the signal and noise in the original seismic data need to be redefined at first.The effective signals of seismic data are enhanced through merging of multi-geometry data.By means of differential application of data with different bin sizes and different arrangement modes,different regimes of seismic waves can be effectively decomposed and imaged separately.During seismic interpretation stage,making the most of the full wave seismic data,and adopting well-seismic calibration on multi-scale and multi-dimension,the seismic attributes in multi-regimes and multi-domains are interpreted to reveal interior information of complex lithology bodies and improve the lateral resolution of non-layered reservoirs.

Spectral-element simulations of elastic wave propagation in exploration and geotechnical applications

We apply the spectral-element method（SEM）,a high-order finite-element method（FEM） to simulate seismic wave propagation in complex media for exploration and geotechnical problems. The SEM accurately treats geometrical complexities through its flexible FEM mesh and accurately interpolates wavefields through high-order Lagrange polynomials. It has been a numerical solver used extensively in earthquake seismology. We demonstrate the applicability of SEM for selected 2D exploration and geotechnical velocity models with an open-source SEM software package SPECFEM2D. The first scenario involves a marine survey for a salt dome with the presence of major internal discontinuities,and the second example simulates seismic wave propagation for an open-pit mine with complex surface topography. Wavefield snapshots,synthetic seismograms,and peak particle velocity maps are presented to illustrate the promising use of SEM for industrial problems.

Exploration of fault-zone trapped waves at Pingtong Town,in Wenchuan earthquake region

Pingtong Town is located on the fractured zone of the Wenchuan 8.0 earthquake, and is seriously damaged by the earthquake. Our observation line is centered at an earthquake exploration trench across the fractured zone in the NW-SE direction, and is about 400 m long. The results reveal trapped waves in the rup- tured fault zone of the earthquake, and indicate a great difference in physical property between the media inside and outside the fault zone. The predominant frequency of the fault-zone trapped waves is about 3 -4 Hz. The wave amplitudes are larger near the exploration trench. The width of the fault zone in the crust at this location is estimated to be 200 m. In some records, the waveforms and the arrival times of S waves are quite different between the two sides of the trench. The place of change coincides with the boundary of uplift at the surface.

Reservoir prediction using multi-wave seismic attributes

The main problems in seismic attribute technology are the redundancy of data and the uncertainty of attributes, and these problems become much more serious in multi-wave seismic exploration. Data redundancy will increase the burden on interpreters, occupy large computer memory, take much more computing time, conceal the effective information, and especially cause the ＂curse of dimension＂. Uncertainty of attributes will reduce the accuracy of rebuilding the relationship between attributes and geological significance. In order to solve these problems, we study methods of principal component analysis （PCA）, independent component analysis （ICA） for attribute optimization and support vector machine （SVM） for reservoir prediction. We propose a flow chart of multi-wave seismic attribute process and further apply it to multi-wave seismic reservoir prediction. The processing results of real seismic data demonstrate that reservoir prediction based on combination of PP- and PS-wave attributes, compared with that based on traditional PP-wave attributes, can improve the prediction accuracy.

Characterization and application of submarine seismic ambient noise in the Bohai Sea and Yellow Sea

Submarine seismic ambient noise imaging combines current marine and on-land seismic detection technologies.Based on data from several broadband shallow-sea type ocean bottom seismometers(SOBSs)deployed in the Bohai Sea and north Yellow Sea,this paper analyzes the submarine seismic ambient noise characteristics.It explores the theory,technology,method and application of the submarine seismic ambient noise imaging using the single-point horizontal and vertical spectral ratio method(HVSR).The observations yield the following results:1)Submarine seismic ambient noise has consistent and constant energy,making it an appropriate passive seismic source for submarine high-frequency surface wave investigation.2)Using the HVSR approach,a single threecomponent OBS could differentiate between the basement and sediments.Array seismic observation could be utilized to extract the frequency dispersion curve and invert it to obtain the velocity structure for more accurate stratification.3)The SOBS we use is suitable for submarine surface wave exploration.4)Tomography results with greater resolution and deeper penetration could be obtained by combining active and passive sources in a simultaneous inversion of the HVSR and frequency dispersion curve.Seamless land-to-ocean seismic research can be accomplished with submarine seismic ambient noise imaging technologies.

跨孔地震CT层析成像在岩溶物探中的应用

用跨孔地震CT层析成像技术对建筑场地的地层进行高精度的探测,获取勘察场地测试孔间的地层信息和不良地质体分布情况,从而实现对建筑场地全尺寸的地质预报。通过引入尺寸误差和区位误差参数,结合软件反演成像进一步分析,评价跨孔地震CT层析成像技术对于建筑场地地层探测效果、尺寸探测效果。结合钻孔勘察结果,将跨孔地震CT层析成像分析结果绘制成综合地质解释剖面图,可得到场地全尺寸范围内的地层情况。针对不同的探测目标,地震波的探测精度主要受探测目标体与周围环境之间地震波传播速度差异的影响决定。结果表明,将跨孔地震CT层析成像应用在岩溶物探中是可行的,结合地层信息可较清晰地了解地质情况,有利于后期的设计和施工。

Subtle traps prediction using sequence stratigraphy and 3D seismic technology: A case study from Qikou depression in Huanghua basin

Forecasting subtle traps by sequence stratigraphy and 3D seismic data is a sensitive topic in hydrocarbon exploration. Research on subtle traps by geophysical data is the most popular and difficult. Based on the sufficiently drilling data, log data, core data and 3D seismic data, sediment sequence of Qikou depression, Huanghua basin was partitioned by using sequence stratigraphy theory. Each sediment sequence system mode was built. Sediment faces of subtle traps were pointed out. Dominating factors forming subtle traps were analyzed. Sandstone seismic rock physics and its response were studied in Tertiary System. Sandstone geophysical response and elastic modulus vary laws with pressure, temperature, porosity, depth were built. Experimental result and practice shows that it is possible using seismic information forecasting subtle traps. Integrated using geology, log, drilling data, special seismic processing technique, interpretation technique, high precision horizon calibration technique, 3D seismic visualizing interpretation, seismic coherence analysis, attribute analysis, logging-constrained inversion, time frequency analysis, subtle trapsobject is identified and interpreted. Finally, advantage object of subtle trap in this area was determined. Bottomland sand stratigraphic and lithologic reservoirs in Qinan slope zone have been founded by means of high resolution 3D seismic data field technique, high resolution 3D seismic data processing technique and seismic wave impendence inversion technique.

面向复杂介质的地震散射波采集技术

地震勘探是一项以地震采集技术为基础的系统工程。变革地震采集技术既是采集装备升级、波场理论创新的发力点,也是解决地震处理、解释技术问题的源头。地震勘探发展历程体现了采集装备能力提升、地质需求驱动、波场理论拉动的作用,其中,地震采集技术既充满活力,也面临着深刻的挑战。面对小尺度、非层状、非均匀介质成像问题,以及大数据与人工智能高速发展的时代背景,以共中心点叠加为特征,采用稀疏、规则、单一观测系统的反射波地震采集技术越来越显示出不适应性,为适应小尺度、非层状、隐蔽性目标成像要求,以共中心点离散化为特征,采用随机、遍历性、多观测系统的散射波地震采集技术势在必行。作为散射波地震采集技术的理论基础,随机理论及概率波的研究逐渐得到重视。

Grounded-source short offset transient electromagnetic method:Theory and applications in deep mineral exploration

The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded transmitters.The Long Offset Transient Electromagnetic(LOTEM)method employs a grounded-source transmitter,relying on a far-source observation mode and plane wave approximation for detection.However,LOTEM's far-source configuration weakens signal strength,and the plane wave approximation reduces precision,limiting effective detection depth to approximately 1000 m with a comprehensive error of about 15%.Recently,we have developed the grounded-source Short Offset Transient Electromagnetic(SOTEM)method,achieving greater detection depth and accuracy within the 500–2000 m depth range,a crucial interval for mineral resource exploration.This study explores the theoretical framework,instrumentation,data processing,and field applications of SOTEM.Based on a point charge element model,SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source observation.High-power,high-resolution,wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method's effectiveness.Application of SOTEM to the deep exploration of the Zhou'an Ni-Cu-PGE deposit in Henan Province yielded high-resolution imaging of conductivity structures to about 2.5 km depth.These results,consistent with existing drill data,delineated mineralized ore bodies from surrounding formations,identified zones of mineralization potential,and suggested extensive resource prospects in the region.

巴基斯坦东部海域中生代地层发现与油气意义

巴基斯坦海域历经60余年油气勘探,长期以新生界为主要目标,对中生代地层展布、构造演化特征等认识不清。巴基斯坦东部海域中—新生代时期经历了复杂的构造—沉积演化过程,新生代受喜马拉雅隆升影响而沉积了巨量陆缘碎屑物质,因此是研究诸多重大基础科学问题的极佳场所。受白垩纪晚期区域火成岩影响,对该区中生代地层是否存在、如何展布等问题一直存在较大争议,这极大限制了区域油气勘探活动的开展。本研究基于新采集的高品质二维地震剖面,突破了火成岩层的屏蔽作用,通过地震反射界面刻画、地震波组特征分析和层速度分析等手段,揭示了中生代地层在巴基斯坦东部海域广泛分布,中生代地层受控于同期活动的强烈伸展断陷作用,被隆坳相间的构造古地理格局分割在多个规模不等的次级凹陷内部。整体厚度800~10000 m,表现为东南厚、西北薄,向北和向西超覆,最大沉积厚度位于研究区东南和西北两个区域,该套地层在陆域下印度河盆地已证实为重要烃源岩层,因此海域中生代地层的发现有效拓展了该区未来油气勘探方向和潜在价值。

多波地震联合技术精细雕刻隐蔽河道砂体——以四川盆地西北部ZT地区沙溪庙组为例

四川盆地陆相致密砂岩气资源丰富,是目前天然气增储上产的重要领域,但侏罗系沙溪庙组沙一段河道砂体纵向多期叠置,横向同期交汇且河道砂体类型多样,隐蔽性强,形成了复杂多变的地震反射特征,准确刻画河道砂体难度极大。为了解决四川盆地西北部(以下简称川西北)ZT地区沙溪庙组一段(以下简称沙一段)多期河道砂体及储层刻画不清晰、精度低的问题,采用新采集的三维地震三分量转换横波(PS波)资料,结合PP波叠前数据和常规叠后地震资料,在正演模拟基础上,形成了多波地震联合雕刻河道砂体关键技术,并分析了河道砂体多波地震响应特征随砂体孔隙度的变化规律。研究结果表明:(1)砂体顶界PP波地震响应随孔隙度增大由强波峰转变为强波谷,而PS波地震响应不随物性变化发生极性反转,基于横波对岩性的刻画可有效识别多期隐蔽河道砂体;(2)相较反映横波阻抗变化率的叠前P-G属性,PS波振幅能量更聚焦,雕刻的河道砂体横向展布特征更清晰,边界更清楚;(3)叠前P-G属性具有更高的纵向分辨率,有利于区分叠置砂体,并落实砂体的发育期次。结论认为,多波地震技术联合充分发挥P-G的高分辨率优势确定纵向砂体发育期次,发挥PS波横向连续性优势刻画横向边界,实现了ZT地区沙一段河道砂体的完整精细雕刻,生产应用效果显著,并为该区井位部署和储量升级提供了有力技术支撑,为四川盆地陆相致密砂岩气规模效益开发奠定了坚实的基础,同时有力推进了多波地震勘探技术的发展。

多源频率域地震勘探技术及应用

在城市地球物理勘探中,因受到城市中各种强电磁机械干扰和交通建筑阻隔,诸多地球物理勘探技术勘探效果不佳。本文基于瞬态面波、微动台阵和微动谱比,采用多点三分量低频传感器获取的多源频率域地震数据,综合提取两种特征曲线后进行联合反演,实现融合3种技术的多源频率域地震勘探。其中,提出了双源综合频散谱提取技术、双源特征曲线联合反演技术和基于非均匀介质的等效均匀介质正演技术,勘探成果的精度和效率均得到了提高,在工程实践中得到验证。

中国石油陆上高难度探区地震勘探突破与启示

目前,中国石油油气勘探开发由隆起区向盆地斜坡、湖盆中心、盆地周缘不断拓展,目的层由中浅层向深层-超深层、对象由常规向非常规油气不断扩展,勘探开发面临探区更复杂、目标更隐蔽、作业难度更高等难题。针对陆上高难度探区地震勘探,中国石油强化地震资料采集、处理、解释等技术攻关,形成了“两宽两高(宽方位、宽频、高密度、高覆盖)”采集、“双高(高分辨率、高保真)”处理、真地表成像处理、叠前储层定量预测等技术系列,支撑了高难度探区勘探持续突破和储量长期稳定增长,实现油气产量稳中有升。以上成果的取得,得益于物探技术理念的转变,提出了“油气在地质家的脑海里,更藏在高品质的地震资料里”的找油找气新理念;得益于把握住了陆上地震勘探技术突破的牛鼻子,提出了“目标在深层,问题在浅层,关键是速度,核心是精细”的技术思路;得益于管理思路的创新与转变,建立了完整的物探技术管理体系,使各探区地震资料品质大幅度全面提升。这种认识上的突破和管理创新将指导下一步陆上油气地震勘探技术向全方位、高密度、全数字、多参数、自动化、智能化、全波形、全波场等方向发展。

一种利用低频反鬼波滤波器提升深部地震信号能量的方法

海洋地震勘探中鬼波的存在压制了信号中的低频能量,而地球深部结构主要对应低频信号成分,提升受到鬼波压制的低频成分对深部结构探测具有重要意义。鬼波压制过程的关键参数之一是鬼波与一次反射波的到时差,其精度直接影响鬼波压制的效果。受起伏海面、崎岖海底、反射层深度变化和不均匀体分布等因素的影响,鬼波与一次反射波的到时差常无法准确估计,导致鬼波压制无法取得较好的效果。本文在鬼波与一次反射波到时差估计不准的情况下,从反鬼波滤波器的特性出发,设计不扰动高频、仅提升低频的滤波器,绕开对鬼波的压制,仅致力于对低频信号的能量提升。模型测试结果表明:利用本文方法处理后的波形,在形态上接近于无鬼波干扰的一次反射波形,且地震信号主频越低、拖缆的沉放深度越小,本方法对低频信号的能量提升作用越强。在南海实测深反射地震剖面上的测试应用也取得了较好的效果。

槽波地震勘探技术在山西寿阳段王煤矿中的应用

为了解决山西寿阳段王煤业集团有限公司090606回采工作面内部陷落柱、断层等影响回采的地质构造数量多、规模大、影响工作面安全回采这一问题,利用井下槽波地震勘探技术对工作面内部陷落柱、断层等地质构造进行采前探测。通过前期室内勘探设计,中期现场数据采集,后期数据处理、成果分析等过程,精准圈定了090606工作面内部影响回采的地质构造(陷落柱、断层等)的位置及影响范围,并根据成果报告,提前对工作面的回采工作采取了有效措施,有效降低了工作面回采过程中由隐伏地质构造所造成的风险,收到了较好的经济技术效果。

综合物探对多煤层采空区综合勘查对比研究

为了探明多煤层采空区分布,利用地震波频率谐振勘探法及可控源音频大地电磁测深法进行综合勘查。本文阐述了地震波频率谐振勘探法及可控源音频大地电磁法的方法原理以及采空区的地球物理特征,结合实际案例,从波阻抗断面图及视电阻率断面图,分析了采空区的异常特征并圈定采空区范围,后经钻探验证,推断结果与实际情况基本吻合,并对两种勘探方法的优缺点进行了分析。本次研究将地震波频率谐振勘探技术应用于多煤层采空区的探测取得了良好的效果,对多煤层采空区的探测有很重要的借鉴和指导意义。

城际铁路岩溶综合勘察方法研究

灰岩地区岩溶发育情况对城际铁路的施工及安全运营有重要影响,因此针对性进行高精度地质勘察十分重要。为降低复杂城区环境的影响、提高城际铁路岩溶勘察的精度与效率,依托某城际铁路,通过理论与实际探测效果对比,统计分析实际探测溶洞的大小并对比分析200 m长度试验区域跨孔地震CT、钻孔、等值反磁通瞬变电磁法(OCTEM)与微动4种方法的岩溶探测效果,研究不同孔间距对跨孔地震CT的探测效果,跨孔地震CT探测溶洞的分辨率,特定区域跨孔地震CT波速解释原则以及OCTEM、微动在不具备开展跨孔地震CT条件时的勘察效果。研究结果表明,跨孔地震CT工作中15 m孔间距相对30 m孔间距原始数据质量更高,岩溶识别率、分辨率更高,岩溶发育规模、空间位置形态的确定更准确,后期施工注浆及注浆用量的估算更可靠;15 m孔间距跨孔地震CT能够对2 m以上的溶洞进行精准揭示;在特定区域可以根据地震波速大小,将灰岩地区岩溶发育情况定量解释为风化层、溶蚀裂隙、溶洞以及较完整灰岩;在不具备跨孔地震CT工作条件时开展OCTEM和微动进行补充勘察,可以探明较大的溶洞,定性查明灰岩地区岩溶发育的程度。勘察方法具有勘察精度高以及不易受城际铁路沿线环境影响的特点,对城际铁路工程岩溶勘察具有重要意义,可在其他城际铁路岩溶勘察中推广使用。

可控冲击波震源技术在陕北沙漠区地震勘探的应用

针对现有地震勘探震源存在问题和局限性,创新性地将金属丝电爆炸可控冲击波技术应用于地震勘探中,分析了金属丝电爆炸可控冲击波技术和产生原理。在掌握金属丝电爆炸可控冲击波技术作为地震勘探震源技术的特点和陕北沙漠地区进行现场激发试验的情况下,从理论分析和现场试验验证了金属丝电爆炸可控冲击波技术作为震源技术的可行性。通过对获取的数据进行定量分析,认为可控冲击波技术可作为一种新型震源技术,且在陕北沙漠区煤田地震勘探领域具备较好的应用发展前景。同时,通过总结试验中存在的问题,为下一步的改进提供方向。

反射槽波探测法在煤层褶曲与断层识别中的研究与应用

【背景】煤矿智能化转型中,精准识别地下异常体对地质透明化体系构建至关重要,褶曲异常体的精确探测是井下物探技术的难点,其准确辨识对减少掘进成本、回采难度及安全风险有重要意义。【目的和方法】基于以往的槽波勘探实践,发现褶曲对槽波的传播特性具有显著影响,但传统槽波反演技术难以区分褶曲与断层。为此,构建了几何形态类似、勘探距离相等的断层与褶曲数值模型,首先运用三维波场模拟技术挖掘波场信息,明确了二者波场响应差异;其次采用绕射偏移成像方法反演处理,获取了成像结果。【结果和结论】研究结果表明:(1)褶曲异常相较于断层,其反射槽波波形更为分散且模糊,不同反射点能量分布不均。(2)褶曲异常在远偏移距处的直达槽波信噪比高于断层构造,且能减缓直达槽波的衰减速度,使得直达槽波在褶曲异常中的传播距离约为断层构造中的1.5倍。(3)断层的反射槽波与直达槽波能量差异较小,而褶曲异常则表现出较大的能量差异。(4)褶曲异常的反射槽波主频低于断层构造,并导致直达槽波与反射槽波的频带变宽;褶曲异常反射槽波频率和速度均略高于直达槽波,断层构造此特征不明显。(5)断层构造的反射面通常位于断层面中上端,而褶曲异常的反射面则倾向于褶曲面中部,且褶曲异常的绕射偏移成像反射面在连续性上较断层构造差。基于上述波场特征与频散特性的深入分析,以山西阳泉某矿15号煤层为例,通过反射槽波绕射偏移成像技术,成功实现了巷道侧帮煤层中断层与褶曲的定性识别,并清晰描绘了褶曲的发育形态。研究成果不仅为采区工作面的合理布局提供了更为精确的地质依据,也为煤矿的安全生产、高效开采提供了有力的技术支撑。

基于分布式螺旋光缆的地震勘探水中接收试验

由于传统直光纤DAS存在侧向灵敏度较低的局限性,因此将分布式声波传感应用于地面地震勘探中接收射线方向几乎与光纤轴向垂直的地震反射信号的案例较少。螺旋缠绕光缆(HWC)可以增强分布式光纤对侧向的灵敏度,使DAS在地面地震勘探中推广应用成为可能。基于对光纤相对应变与缠绕角度和入射角关系的分析优选,并考虑目前分布式螺旋光缆生产工艺的难易程度和造价情况下,将一条部分段缠绕角度为30°,另一部分段缠绕角度为60°,总长2 km的分布式螺旋光缆布设在江苏某地震采集工区内的河中进行了HWC地面地震采集探索试验。经过对分布式螺旋光缆采集数据与附近地面布设的节点采集地震数据及不同缠绕角度光缆采集的单炮和剖面的对比分析,发现30°缠绕角度的分布式螺旋光缆能采集到地面地震反射波信号,而且有效波波组特征清晰连续。试验采取了水中接收的方式,试验结果为采用分布式螺旋光缆开展地震勘探提供了参考和依据。