论文详情
可控震源作为一种对环境友好、使用高效、方便控制的地震波激励源近70年来在油气地震勘探中得到了广泛应用。绿色油气勘探理念、“两宽一高”地震数据采集技术和FWI地震波反演成像技术为可控震源地震勘探带来了新的机遇和新的问题。高密度地震勘探的真正内涵是炮点和炮线密度的提高,若干可控震源同时激发引出的高效采集技术可以对冲巨量炮点激发带来的采集效率降低和成本上升。陆上宽带地震勘探的核心是震源激发且检波器接收到宽带的反射子波,理论上可控震源能提供客户定制的宽带反射子波。实践表明可控震源能够提供低至2～3Hz的地震数据,这为FWI技术的成功应用奠定了数据基础。陆上高精度地震勘探中可控震源技术起到了关键作用。为此,重点讨论与分析了当前可控震源地震勘探面临的问题,包括高效地震数据采集方案、可控震源激发的噪声波场、混叠数据的解混叠、压缩感知理论下的高效采集等问题,并提出了相应的对策。重点阐述了客户定制反射子波的地震勘探理念,提出可控震源地震勘探技术未来发展应注重:①建立可控震源子波设计中扫描信号的单频时长与单频能量之间的关系;②实际地震数据采集过程中应通过自适应地下介质变化反过来优化扫描信号;③采集中尽量使用一组不同的震源组合进行编码扫描;④应在最优化理论控制下,以预定的宽带反射子波作为目标,用接收到的地震反射子波与预定的宽带反射子波之间的差异作为反馈量,修正扫描信号。据此开发出一套高效采集软件控制系统进行最佳高效采集,能够促进可控震源地震勘探技术在石油工业及相关领域的广泛应用。
Vibroseis has been widely used in oil and gas seismic exploration during the past 70 years,as a kind of environment-friendly,efficient,and flexible seismic source.The concept of environment-friendly conservation,application of the broadband,wide-azimuth,and high-density seismic data acquisition technology,and development of the full waveform inversion technology bring new opportunities and challenges to the vibroseis-based seismic exploration.The distinctive characteristic of the high-density seismic exploration is the increase in shot density.The efficient acquisition technology derived from the simultaneous excitation of several vibroseis sources can offset the reduction of acquisition efficiency and the increased cost incurred with the excitation of massive shots.The core of the wide-band land seismic exploration is the excitation of a seismic source and recording of wide-band reflection wavelets by geophones.Theoretically,the vibrator can provide a customized wide-band reflection wavelet.It has been proved that the vibrator can provide seismic data with a frequency of 2~3Hz.The vibroseis technology plays a key role in high-precision seismic exploration on land.Herein,the current issues in vibroseis seismic exploration are analyzed and discussed,including the characteristics of the noise field produced by the vibroseis,deblending techniques,and efficiency of various seismic acquisition schemes,particularly within the framework of the theory of compressed sensing.Corresponding countermeasures to address the above-mentioned issues were suggested,and a seismic exploration concept entailing customized reflection wavelets was proposed.To further develop the vibroseis seismic exploration technology,the following tasks were identified:①establishing a relationship between the duration and energy of a single frequency of the sweep signal in the design of vibroseis wavelets;②formulating an adaptive sweep signal during field data acquisition according to the underground medium;③maximizing the differences between the sources encoded in each combination;④utilizing the difference between the received reflection wavelet and the target wavelet as a feedback to modify the scan signal,within the framework of the theory of optimal control,with the target being the predetermined broadband wavelet.Furthermore,an acquisition controlling software system should be developed to improve the efficiency of the acquisition process.The application of the vibroseis seismic exploration technology feasible at large depths in the petroleum industry and related fields is anticipated.
南方海洋科学与工程广东省实验室(湛江)资助项目(ZJW-2019-04),国家重点研发计划深海关键技术与装备重点专项(2019YFC0312004)、国家重点研发计划变革性技术关键科学问题重点专项(2018YFA0702503)、国家自然科学基金(41774126)和国家科技重大专项(2016ZX05024-001,2016ZX05006-002)共同资助。