频率域海洋电磁法一维正演响应特征研究

Research on the Features of 1D Forward Response of Frequency-Domain of Marine Electromagnetic Method

海洋可控源电磁法(CSEM)是目前在海洋中进行找油气资源等矿产的常用电法勘探方法,它采用人工可以控制的场源作为激励源,测量海底电磁场值。相对其他电法勘探技术,海洋CSEM具有探测深度范围大、破坏性小、实施简单、适应性强、探测准确等特点。然而,海洋电磁理论是建立在水平发射偶极的基础上,由于自然因素(诸如海底洋流作用、海风等)的影响,海洋可控源发射偶极可能不能按理论设想进行工作,造成测量数据与理想状态的水平电偶极子的电磁响应有较大的偏差。本文以合理设置相关参数及分析各种影响因素为目的,利用所建立的相关一维模型得到的理论数据对影响因素进行了深入分析,并为合理选取各相关参数提供了依据。

Marine controlled source electromagnetic method is carried out to find common marine electrical prospecting methods, such as mineral oil and gas resources, which uses artificial field source that can be controlled as an excitation source to measure the value of undersea fields. The establishment of the theory is based on the lev-el of the transmitter dipole. Due to natural factors （such as the role of undersea currents, and winds, etc.）, the im-pact of marine controlled source dipole transmitter may not work as envisaged by theory, resulting in a large devia-tion in the measurement of data and the ideal state of a horizontal electric dipole electromagnetic response. Mean-while, different emission frequencies, deep sea and various resistivity reservoirs produce different responses. The paper aims to research on how to set reasonable parameters （such as transmission frequency） and to analyze vari-ous factors. Data related to the use of one-dimensional theoretical model were established based on the factors as well as the reasonable selection of relevant parameters.