层状介质模型多道海洋直流电法拖缆变形数据校正模拟分析

Simulation analysis of the deformation of multichannel marine DC electrode towing cable

多道海洋直流电法是海洋地球物理探测技术的重要手段之一,应用该方法进行海洋探测时,其用于数据采集的拖缆在外力作用下会产生变形,导致测量的数据产生畸变,进而影响反演结果.本文基于视电阻率、视电阻率变异比及视电阻率变异系数等参数,通过数值模拟的方法分析了拖缆不同曳航高度、不同变形形状、不同变形方向、不同变形幅度等因素对测量数据及校正后数据的影响并进行定量评价,基于校正后的数据,引入异常变化比等参数综合分析拖缆变形对含气层和孤立含气区异常特征分辨的影响.研究结果表明,拖缆变形不仅会导致测量的视电阻率数据发生畸变,还会使利用实际装置系数校正后的数据视也产生偏差,数据畸变的特征与拖缆变形形式及曳航高度有关,可用视电阻率、视电阻率变异比、视电阻率变异系数综合分析对数据的畸变水平进行量化评价.在一定变形范围内,校正后的数据可以显现含气异常,但反映能力有所下降;当拖缆变形幅度过大时,校正后的数据会差生大幅度波动,不仅淹没原有含气反映,甚至产生虚假异常.

The multi-channel ocean direct current method is one of the important methods of ocean geophysical exploration technology. When using this method for ocean exploration, the streamer used for data collection will deform under the action of external force, which will cause the measured data to be distorted and affect Inversion results. Based on the apparent resistivity, apparent resistivity variation ratio, and apparent resistivity variation coefficient, this paper analyzes the towline’s different towing heights, different deformation shapes, different deformation directions, different deformation amplitudes and other factors on the measurement data. The impact of the corrected data is quantitatively evaluated. Based on the corrected data, parameters such as the abnormal change ratio are introduced to comprehensively analyze the impact of streamer deformation on the identification of abnormal characteristics of gas-bearing zones and isolated gas-bearing zones. The research results show that the deformation of the streamer will not only cause the measured apparent resistivity data to be distorted, but also the data after correction using the actual device coefficients. The characteristics of the data distortion are related to the form of the towline deformation and the towing height. The distortion level of the data can be quantitatively evaluated by comprehensive analysis of apparent resistivity, apparent resistivity variation ratio and apparent resistivity variation coefficient. Within a certain range of deformation, the corrected data can show abnormal gas content, but the ability to reflect is reduced;when the deformation of the streamer is too large, the corrected data will fluctuate greatly, and the original gas content will not be flooded. And even produce false exceptions.