陆上勘探低频信号的接收与恢复

Sensing and recovery of low-frequency signals in onshore surveys

低频信号对于地震数据处理和综合地质解释均具有重要意义,被广泛应用于波形反演、速度分析、低频伴影检测和深层成像等。但从接收的角度看,陆上勘探低频信号采集并不容易。对低频信号的4种获取方法,即机械低频、电低频、数学低频以及“物理合并数学”低频方法进行了对比,分析了4种方法的适用条件,提出电低频检波器设计和制造需要遵循5个原则,包括校正量准确、允差合理、体积和重量不显著增加、施工方便以及价格合理等。研究认为,MEMS加速度检波器在1.0~2.0Hz以上的低频比较可靠,且只有在将其数据积分为速度进行处理时低频优势才能显现。数学低频(检波器反褶积)对于常规动圈式检波器拾取数据的低频端具有良好的恢复作用且具有较高的推广价值。初步检波器反褶积试验表明,叠加剖面低频能量显著增强,信噪比提高,为低频信号在处理、解释阶段的深度应用奠定了数据基础。建议在后续工作中进一步探索低频信号在数据处理和地质解释阶段的深度应用。

Low-frequency signals are of great significance for seismic data processing and geological interpretation,and they are widely used in full waveform inversion,velocity analysis,low-frequency shadow detection,deep target imaging,etc.However,low-frequency signals are not easily obtained in onshore surveys.In this study,four available approaches for the acquisition of low-frequency signals are presented and analyzed,namely the mechanical,electrical,mathematical,and‘physical plus mathematical’approaches.It is suggested that the design and manufacturing of electrical low-frequency sensors as part of these approaches should follow five principles:accurate correction,reasonable tolerance,limited volume and weight(to ensure coupling well),easy operation,and reasonable price.Furthermore,it is shown that the low-frequency signal of MEMS accelerometer above 1.0~2.0Hz is relatively faithful.However,the advantage of accounting for low-frequency data comes true only when the data are integrated into velocity for processing.Overall,mathematical low-frequency recovery(geophone deconvolution)works well beyond 1.0~2.0Hz on the data acquired by moving coiled geophones,and can potentially be applied for data processing and geological interpretation in future.