海洋可控源电磁法快速成像研究

Study on fast imaging of marine controlled source electromagnetic

海洋可控源电磁法在正反演算法上受到计算速度和精度的限制,需要大量的时间得到地下结构断面数据。为了海上快速识别海底高阻异常区域,提出一种通过计算视电阻率快速成像的算法,避开复杂的反演计算,在极短的时间内得到电性分布拟断面图,定性解释地下地质结构。算法通过一维和二维模型计算验证其可靠性和稳定性,代入海试数据计算拟断面图,与传统海洋电磁法反演结果对比各自优劣。结果表明,在一维和二维模型中,算法可靠且稳定,高阻异常体横向边界分辨率较高,拟断面图高阻异常分布与模型结构拟合度高,海试实测数据计算结果同样显示了与反演断面图有较高相似度的高阻异常分布,且运算时间远远小于反演计算。

Marine controlled source electromagnetic (CSEM) is limited by calculation speed and accuracy in forward and inversion algorithm. It takes a lot of time to obtain information of underground structures. In order to quickly identify the underground high resistivity anomalous area in time, an algorithm of fast imaging by calculating apparent resistivity is proposed. This avoids complex inversion calculation and obtains pseudosections electrical distribution map in a very short time to qualitatively interpret underground geological structure. The algorithm validates its reliability and stability through one-dimensional and two-dimensional model calculation, and calculates the pseudo-sectional map by substituting the sea test data, and compares their advantages and disadvantages with the traditional marine electromagnetic inversion results. The results show that in one-dimensional and two-dimensional models, the algorithm is reliable and stable, the lateral boundary resolution of high-resistivity anomaly is good, the high-resistivity anomaly distribution of simulated cross-section map and the fitting degree of model structure are high. The calculation results of sea test data also show that the high-resistivity anomaly distribution has a high similarity with the inversion cross-section map, and the calculation time is much smaller than the inversion calculation.