海底顶层电火花源立体探测系统及其成像基础研究

Recent surge of interests from many countries about marine gas hydrates, mineral resource and ocean bottom biosphere has demanded for more precised detection apparatuses and advanced imaging methods to map submarine strata. We propose to study the scientific issues associated with a combined use of different seismic methods in mapping the top submarine strata in four aspects. First, study single sparker source, composite sources, and coded sources for their wavefield responses and mechanisms, establish models for single-source characteristic wavelets and optimal source combinations. Second, search for optimal ways to combine streamer cables, vertical cables, OBC, and OBS into a stereo sensor grid, find the optimal deployments that will maximize the illuminations for various targets in the top submarine strata, and test the sensor grid by measuring the sparker sources. Third, search for ways to improve the resolution and fidelity of the detection system consisted of the sparker sources and stereo sensor grid, and test the system with chosen targets in the field. Fourth, to match the acquisition setup and data types of the detection system, develop advanced imaging methods including tomographic velocity model building, prestack depth migration, and waveform inversion for submarine strata. Through fundamental research and field tests, we expect the new detection system will be able to achieve meter-level resolution for the top submarine strata beneath about 1000 meters of water column; resulting in a new marine seismic detection system and imaging technology with independent interlectural property right and the advantages of stereo, high-resolution, and broad angular illumination range. The completion of this project shall significantly improve the marine geophysical exploration capabilit of China, and to effectively serve the needs for ocean bottom scientific studies, resource exploration, and monitoring of geohazards such as submarine landslides and oil spills.

近年来各国对海洋水合物、矿产资源和洋底生物圈的兴趣急剧增加，迫切需要能够精确探测海底结构的先进探测方法。本项目拟从四个方面研究如何将各种地震探测方法组合成一个新型海底立体探测系统及有关科学问题：研究电火花单震源、组合震源和编码震源的波场响应机理，建立单震源子波信号特征和最佳震源组合模式；研究如何组建水平缆、垂直缆、海底缆和OBS立体观测网，对海底顶层不同探测目标形成最佳观测，通过海试标定电火花源特征；研究探测系统数据波场分离方法，提高分辨率和保真度，并选定目标进行实测；研究与探测系统匹配的海底层析建模、叠前深度偏移和波形反演等先进成像方法。通过基础研究和实验，争取在千米水深海底顶层达到米级分辨率,最终形成一套具有自主知识产权、立体化、高分辨率、宽方位角海底顶层探测系统和成像理论。该研究将有力地提高我国海洋物探理论水平，有效地服务于资源勘探、海底科考，实现对海底滑坡、渗油等灾害的高精度监测。

为获得能够精确探测海底顶层千米地层所需高保真度广角地震资料,项目组研究把各种先进海洋地震探测方法构建成一个新型立体探测系统，研究该立体探测系统所涉及的理论基础和关键科学问题，并验证立体观测系统的可行性与分辨率。课题组在五年项目执行期内按照项目计划书完成了各项既定任务，在电火花等海洋编码震源子波模拟与组合响应研究、海洋立体地震观测网格的优化设计、立体观测系统数据处理技术、地震速度建模方法研究、立体观测网基础部件的研制与测试等方面均取得了显著进展。项目组各成员协同合作，研制了国内首个海洋垂直缆观测系统，获得了高精度野外实测数据，填补了我国在该领域的空白；研制了海洋编码震源子波模拟、立体观测系统优化以及对海底顶层不同探测目标的布设方案；针对立体探测系统资料特点，研发了与其匹配的数据处理方案和先进的地震成像方法，包括多尺度可变形层析成像、地震反射波和折射波联合层析成像、叠前逆时偏移、全波形反演和波阻抗反演方法,并发展了相应的计算机软件；形成了适用于立体观测系统的速度建模和地震成像流程，达到使用立体观测系统进行高精度海底顶层结构探测的要求。对这些方法和软件进行了大量测试，并成功应用于从南海、黄海等地采集的野外资料，取得了良好效果，对海底千米顶层地层达到米级分辨率。.项目标注资助发表论文58篇，其中SCI论文24篇(含已录用待发表6篇)，EI论文6篇，其他期刊论文28篇(含已录用待发表2篇)；申请国家专利28项（其中发明专利19项，已授权3项；实用新型专利9项，已授权7项），和软件著作权登记9项；召开了两届国际研讨会；培养博士研究生7名，硕士研究生46名，博士后3名；在读博士生12名，硕士生40名。