基于Scholte波频散特性的深海海底横波速度反演

深海环境下海水的声波速度是非匀速的,变速的海水会影响海底Scholte波的频散特性,为了提高利用Scholte波频散特性反演海底横波速度的精度,需建立速度连续变化的水平分层海水-分层海底(HLSLS)模型。本文基于波动理论推导HLSLS模型Scholte波频散方程和振幅深度方程。然后,基于南海海水声速剖面和实际海底弹性介质参数,分析深海环境海水速度变化对Scholte波频散特性的影响。最后,将方法用于南海深水OBS地震数据反演得到一条二维海底横波速度剖面,反演结果很好的指示了海底天然气水合物储层的分布。结果表明:深海环境下,利用海底OBS数据中的Scholte波反演海底浅层横波速度结构是可行的,南海实际深水OBS数据应用进一步验证了方法的准确性和实用性。

基于声压敏感核的水下声场地声参数敏感性分析

使用有限频敏感核研究了水下声场对地声参数的敏感特性。利用一阶Born近似推导了接收信号复声压对海底声速变化的敏感核,采用波数积分方法仿真计算声场,得到了不同频段下海底敏感核的幅值及空间分布,分析了不同频段水下声场对海底地声参数的敏感特性。在近距离上结合南黄海海域多道地震实验数据,对利用声压敏感核的幅度进行海底参数敏感特性分析的可行性进行了验证。将该分析方法推广至典型地声环境下,仿真结果表明,近距离传播条件下甚低频段声传播需考虑深达岩石层的地声参数的影响;中高频段则仅需计入多种固结程度沉积层的影响,沉积层下可视为半无限均匀基底。而对于远距离传播,所需考虑的海底层数及深度可根据敏感核的分布相应减小。此外,通过仿真分层海底底质参数对传播损失及时频特性的影响验证了上述结论。

On electro-acoustic characteristics of a marine broadband sparker for seismic exploration

The construction of major marine infrastructure projects and the exploration and development of deep-sea mineral resources require fine imaging of seabed strata and structures.The highresolution marine seismic exploration based on a high broadband sparker source is an important approach to reveal seabed stratum and reservoir structure,and identify geohazard.To optimize the performance of sparker seismic source,we investigated the electro-acoustic characteristics of spark discharge under conditions of different charging voltages and electrode numbers.Results show that the sound source level increased with the increase of the charging voltage,whereas the main frequency decreased when the charging voltage increases.In addition,it was found that the charging capacitance had more obvious influence on the main frequency than the sound source level did.Although the load energy decreased with increasing electrode number,the sound source level still increased but the main frequency decreased.Meanwhile,the primary to bubble(P/B)ratio increased with the increase of the electrode number.To gain a deeper insight into the electro-acoustic characteristics,we investigate the relationship between sound source level and power peak,from which a good correlation was observed.A more practical statistical analysis on the rise rate of current was processed,and a perfect logarithmic function was derived.Furthermore,we found that the main frequency was most possibly subjected to the electrical energy,especially the charging energy per electrode.The results indicate that the charging energy per electrode less than 10 J could increase the main frequency to above 300 Hz.At last,the main frequency could be reduced to 20 Hz when the charging energy of a single-electrode discharge was enhanced to over 4 kJ.This study shall be helpful in developing a sparker seismic source and improving the performance for marine engineering exploration and geohazard assessment.

Multiple Matching Attenuation Based on Curvelet Domain Extended Filtering

The paper develops a multiple matching attenuation method based on extended filtering in the curvelet domain,which combines the traditional Wiener filtering method with the matching attenuation method in curvelet domain.Firstly,the method uses the predicted multiple data to generate the Hilbert transform records,time derivative records and time derivative records of Hilbert transform.Then,the above records are transformed into the curvelet domain and multiple matching attenuation based on least squares extended filtering is performed.Finally,the attenuation results are transformed back into the time-space domain.Tests on the model data and field data show that the method proposed in the paper effectively suppress the multiples while preserving the primaries well.Furthermore,it has higher accuracy in eliminating multiple reflections,which is more suitable for the multiple attenuation tasks in the areas with complex structures compared to the time-space domain extended filtering method and the conventional curvelet transform method.

同步性质控在海洋地震采集中的重要应用

地震采集中震源和仪器记录的同步性质控对地震资料采集质量至关重要。实际地震采集过程中,由于设备的迭代发展,震源与仪器记录的同步性方面有了较高发展,反而在质控过程中容易忽略。一旦发生非人为设置造成的同步误差,会直接影响到采集资料的质量。而且同步误差通常难以准确测量,造成后期数据处理中无法予以精准消除相应误差。本文主要结合中海油服所使用的设备以及在实际施工过程中出现的问题,探讨触发信号异常和GPS授时系统出现异常造成的同步误差发生原因及相应的解决方案。

超短基线(USBL)在OBN定位中的应用

OBN由于其独立采集的特点,正成为在深水OBS海洋地震采集的主流方法。,OBN点位定位精度是决定地震资料好坏的主要因素之一,本文主要介绍新型声学定位系统超短基线(USBL)工作原理,工作过程,以及在OBN作业中的使用方法和应用效果。

海上宽频地震采集技术研究进展

宽频地震采集已经成为海上地震数据采集重要趋势,其能够获得更为丰富的低频和高频信息,对改善地震资料成像和提升地震资料对复杂目标体的解释能力具有重要意义。文章首先对宽频地震资料和鬼波进行了概述,其次重点探讨了目前关注度较高的海上宽频地震采集技术,包括倾斜电缆采集技术、上下双缆采集技术、双检电缆采集技术、同步多级震源采集技术等。

海洋多次波组合压制技术及应用

在分析多次波压制技术原理的基础上,选取确定性海底多次波压制技术、广义表面多次波压制技术及高精度拉东变换多次波压制技术优化组合进行多次波压制,并应用于实际资料中,应用效果表明该组合方法可以有效压制多次波,提高道集质量及速度分析精度。

我国首次完成3000m超深水三维地震勘探

我国大型深水物探船“海洋石油720”搭载我国自研“海经”拖缆地震勘探系统,完成了珠江口盆地2 600 km^(2)的三维地震数据采集。这是我国首次完成超3 000 m超深水三维地震勘探作业,标志着我国自主海洋勘探技术取得重大突破,对保障我国海洋油气开发自主可控、提升我国深海资源开发能力具有重要意义。“海经”是我国自主研发制造的首套海洋拖缆地震勘探采集装备,填补了我国在海洋地震勘探领域装备技术空白,实现了“从0到1”的突破。

基于无监督神经网络匹配算法的叠前表面多次波压制方法

为了有效地压制海上地震勘探数据中的表面多次波,实现勘探目标的正确成像,提出一种基于无监督神经网络的叠前表面多次波匹配算法,将神经网络方法与表面相关多次波压制方法相结合,通过设定学习率不断下降,用无监督神经网络取代匹配滤波算子,对叠前地震数据进行表面多次波的压制,既不需要传统的匹配算法,也不需要在标签数据集上进行训练。在简单合成数据、Sigsbee模型数据和实际数据上的应用结果验证了该方法对表面多次波压制的有效性。

Geometry and 3D seismic characterisation of post-rift normal faults in the Pearl River Mouth Basin,northern South China Sea

Based on high-resolution 3D seismic data acquired in the Pearl(Zhujiang)River Mouth Basin of the northern South China Sea,this study investigated the geometry,spatial extension,and throw distribution of the post-rift normal fault through detailed seismic interpretation and fault modeling.A total of 289 post-rift normal faults were identified in the study area and can be classified into four types:(1)isolated normal faults above the carbonate platform;(2)isolated normal faults cutting through the carbonate platform;(3)conjugate normal faults,and(4)connecting normal faults.Throw distribution analysis on the fault planes show that the vertical throw profiles of most normal fault exhibit flat-topped profiles.Isolated normal faults above the carbonate platform exhibit roughly concentric ellipses with maximum throw zones in the central section whereas the normal faults cutting through the carbonate platform miss the lowermost section due to the chaotic seismic reflections in the interior of the carbonate platform.The vertical throws of conjugate normal faults anomalously decrease toward their intersection region on the fault plane whereas the connecting normal faults present two maximum throw zones in the central section of the fault plane.According to the symmetric elliptical distribution model of fault throw,an estimation was made indicating that normal faults cutting through the carbonate platform extended downward between-1308 s and-1780 s(two-way travel time)in depth and may not penetrate the entire Liuhua carbonate platform.Moreover,it is observed that the distribution of karst caves on the top of the carbonate platform disaccord with those of hydrocarbon reservoirs and the post-rift normal faults cutting through the carbonate platform in the study area.We propose that these karst caves formed most probably by corrosive fluids derived from magmatic activities during the Dongsha event,rather than pore waters or hydrocarbons.

Dynamic Location Method for Shallow Ocean Bottom Nodes Using the Levenberg-Marquart Algorithm

Ocean bottom node(OBN)data acquisition is the main development direction of marine seismic exploration;it is widely promoted,especially in shallow sea environments.However,the OBN receivers may move several times because they are easily affected by tides,currents,and other factors in the shallow sea environment during long-term acquisition.If uncorrected,then the imaging quality of subsequent processing will be affected.The conventional secondary positioning does not consider the case of multiple movements of the receivers,and the accuracy of secondary positioning is insufficient.The first arrival wave of OBN seismic data in shallow ocean mainly comprises refracted waves.In this study,a nonlinear model is established in accordance with the propagation mechanism of a refracted wave and its relationship with the time interval curve to realize the accurate location of multiple receiver movements.In addition,the Levenberg-Marquart algorithm is used to reduce the influence of the first arrival pickup error and to automatically detect the receiver movements,identifying the accurate dynamic relocation of the receivers.The simulation and field data show that the proposed method can realize the dynamic location of multiple receiver movements,thereby improving the accuracy of seismic imaging and achieving high practical value.

南海北部陆坡X区MTDs特征及形态动力学控制因素

海底斜坡地形对浊流的走向及其沉积物的分布与几何形状具有控制作用。越来越多的研究表明,块体搬运沉积体系(MTDs)顶面地形起伏不平,也会影响后续浊流沉积分布。为了进一步探究海底复杂地形如何对后期浊流的沉积分布产生影响,基于南海北部陆坡X区三维地震数据,对研究区发育的MTDs及其顶界面地形进行刻画,利用Fluent软件中多相流双欧拉法和Realizable k-ε湍流模型对MTDs顶面地形进行数值模拟分析。结果表明,在研究区内识别出大规模的块体搬运沉积,地震剖面显示出空白杂乱反射的特征,同时还识别出逆冲断层、挤压脊等典型构造,这些构造导致MTDs顶界面的地形起伏不平。MTDs趾部发育挤压脊,浊流路过时动能逐渐消散,充填挤压脊之间的凹槽,趾部平缓区域沉积分布明显。入流初速度越大,MTDs顶界面受到的侵蚀程度就越严重,且随着模拟过程的结束,后期浊流对MTDs顶界面的侵蚀和沉积分布走向与入口方向平行。

OBN宽方位地震在潜山勘探中的应用

海底节点(Ocean Bottom Node,OBN)因施工灵活,易于避障和实现宽方位,在海洋油气勘探中应用越来越广泛。针对珠江口盆地珠一坳陷惠州26-6潜山裂缝储层,在南海首次实施了OBN三维地震采集,获得了宽方位地震资料。经过信号预处理、噪声衰减、信号反褶积、波场分离与多次波衰减等处理之后,抽取了炮检距向量片(Offset Vector Tile,OVT)道集,进行了多方位网格层析速度建模和叠前深度偏移,获得了丰富的方位各向异性信息。新老资料成像对比显示,OBN宽方位采集能有效避免海底障碍物影响,处理的地震资料信噪比高,潜山顶面及潜山内幕断裂成像优,振幅各向异性椭圆拟合对潜山裂缝储层预测有较大潜力。

Velocity structure in the South Yellow Sea basin based on first-arrival tomography of wide-angle seismic data and its geological implications

The South Yellow Sea basin is filled with Mesozoic-Cenozoic continental sediments overlying pre-Palaeozoic and Mesozoic-Palaeozoic marine sediments.Conventional multi-channel seismic data cannot describe the velocity structure of the marine residual basin in detail,leading to the lack of a deeper understanding of the distribution and lithology owing to strong energy shielding on the top interface of marine sediments.In this study,we present seismic tomography data from ocean bottom seismographs that describe the NEE-trending velocity distributions of the basin.The results indicate that strong velocity variations occur at shallow crustal levels.Horizontal velocity bodies show good correlation with surface geological features,and multi-layer features exist in the vertical velocity framework(depth:0–10 km).The analyses of the velocity model,gravity data,magnetic data,multichannel seismic profiles,and drilling data showed that high-velocity anomalies(>6.5 km/s)of small(thickness:1–2 km)and large(thickness:>5 km)scales were caused by igneous complexes in the multi-layer structure,which were active during the Palaeogene.Possible locations of good Mesozoic and Palaeozoic marine strata are limited to the Central Uplift and the western part of the Northern Depression along the wide-angle ocean bottom seismograph array.Following the Indosinian movement,a strong compression existed in the Northern Depression during the extensional phase that caused the formation of folds in the middle of the survey line.This study is useful for reconstructing the regional tectonic evolution and delineating the distribution of the marine residual basin in the South Yellow Sea basin.

频率—慢度域鬼波压制技术在海底电缆资料中的应用

鬼波压制是海底电缆资料处理中至关重要的一个步骤,业内常采用水陆检合并方法压制电缆鬼波。传统方法在进行水陆检资料匹配处理时,对陆检资料品质要求较高。受仪器设备的影响,陆检资料往往信噪比低,水陆检资料标定系数计算精度低,制约了鬼波压制的精度,同时降低了资料信噪比。为了提高海底电缆资料鬼波压制精度,同时避免合并处理对资料信噪比的降低,本文提出了一种频率—慢度域(f-p)鬼波压制技术,通过在频率—慢度域计算鬼波延迟时间,建立一次波求取的线性方程组,利用最小二乘求解,实现鬼波压制。与传统双检合并方法不同,本方法仅需单个分量数据参与计算,完全数据驱动。通过模型和实际数据测试验证,本方法能够对海底电缆资料单一水检数据或陆检数据实现鬼波压制,达到消除陷波,拓宽地震频带的目的,同时较好地保持了地震资料信噪比。

一种新型的海洋地震观测浮标平台的设计

海洋地震观测是全球地震观测的一个重要组成部分,目前全球海洋地震观测已进入深海海底长期定点实时观测阶段,美国、加拿大、日本和中国台湾地区的几个环太平洋大型海底科学观测项目已趋于成熟,正在推广实用。由于海上干扰因素太多,导致人们对海洋地震观测的进展受阻,急需一种高效、精准、低成本的监测方式来应对,这时浮标的应用就受到了广泛的肯定。浮标可以将实时采集到的数据上传到平台,通过数据处理、统计、比对,量化评价该海域的水质状况,通过分析海洋数据,及时发现问题,并有针对性地作出判断并处理,提高对海洋环境监测的能力,为海洋环境预警提供重要依据。

锂-亚硫酰氯电池的试验与性能分析

能源供给是海洋能源与资源开发需重点突破的核心共性关键技术。文章介绍了锂-亚硫酰氯电池的特性及优势,设计出一种电池舱来保证电池组在海底低温情况下也不会降低放电效率;同时根据哈尔伯格—佩克公式,评估出电池在高温高湿的环境下功能和使用寿命也不会受到影响;最后利用微热量仪测试电池的自放电率,测得在常温条件下电池的年容量损失<1%。电池舱的设计保证了海洋装备供电系统的高效性与安全性,锂-亚硫酰氯电池的使用保障了海底观测的长期续航。

海底节点不同震相逆时偏移成像研究

对近海海域进行地壳速度结构高精度成像有助于深入了解我国近海地震活动、深部孕震构造条件,揭示海域构造特征及其相互作用模式,为海域地震区划和风险评估提供基础支撑。在海底节点观测系统中,由于海底、海平面等强波阻抗差界面的存在,台站记录了较多强能量的后续震相。与初至震相相比,后续震相在地球内部来回反射,传播路径长、携带构造信息多,充分利用后续震相有望获得高精度的地下构造成像结果。逆时偏移是勘探地球物理中精度较高的成像方法之一,且易于实现。将逆时偏移算法引入海底节点初至震相和后续震相成像,采用常规逆时偏移对反射震相进行偏移,对上行一阶海底震相、上行一阶后续震相成像均进行镜像法逆时偏移,通过修改逆时偏移框架,实现初至震相的成像。研究结果表明,逆时偏移能够有效对反射震相进行地下偏移归位;采用镜像法逆时偏移对上行一阶海底震相、上行一阶自由表面震相进行成像,能够有效增大成像范围;修改逆时偏移框架,初至震相能够对断层进行准确定位。

SY/T 7614-2021《海底节点地震资料采集技术规程》的应用情况分析

随着全球石油勘探和开采的不断发展,海底节点采集技术作为一种重要的勘探手段,受到了广泛关注和应用。海底节点采集技术以其高精度、高分辨率和高效率的特点,成为海底地震勘探领域的热点和前沿技术。为了规范海底节点地震数据采集技术,提高数据质量和勘探效率,制定了《海底节点地震资料采集技术规程》。本文介绍了规程的研制背景,分析该规程在石油勘探行业中的应用情况,并总结相关经验和结论。