时空阵列混场源电磁法理论及模拟研究

A theory and simulation study on the space-time array hybrid source electromagnetic method

针对电磁勘探中的混场源输入条件,提出了一种时空阵列混场源电磁勘探方法.假设输入端同时包含天然电磁场源和可控人工场源,输出端进行多站同步观测;基于多输入-多输出系统的分析方法,推导了混场源条件下的时空阵列方程组.提出了系统响应的求解策略,一次性获得所有同步测道对各个场源独立激励时的响应,并分别求取了大地电磁法及可控源电磁法的各种解释参数.在此理论基础上,设计了针对性的施工方案;可控人工场源的选择形式多样,其类型、数量、激励方式及布设位置等不受限制,所有场源的激励可同时进行,无需分步;测区内各测站的布设方式灵活,可根据需要布设单分量测道或多分量测道;同时在测区外布设张量远参考站.利用数值模拟方法,论证了方法的有效性,并与常规方法进行了对比.结果表明,本方法不仅可提高人工场响应的处理精度,还具有一次野外数据采集,可同时获得天然场及人工场电磁响应结果的突出特点,进而提高采集效率,压制噪声影响;本方法集合了天然场源电磁法和人工场源电磁法的优点,为实现不同类型频率域电磁测深方法数据的统一处理提供了思路.

A space-time array hybrid source electromagnetic method is proposed in order to process the electromagnetic prospecting data under the condition of hybrid source input.Natural sources and controlled sources are both considered as input simultaneously,while many simultaneous observation stations are carried out on the earth′s surface as output.By using the analysis method of multiinput-multioutput system,a space-time array equation is derived under the hybrid source condition.A solution strategy of the equation is presented,to obtain the system responses for all the observation channels corresponding to each sources,and then the interpretation parameters such as impedance tensors,apparent resistivities and phases corresponding to different sources can be estimated from the system responses.Based on this theory,the specific implementation scheme of the method is designed.The selection of controlled sources is varied,including unrestricted types,quantities,incentives and locations.All the source excitation can be carried out at the same time,with no need for proceeding by steps.The layout is flexible for the stations inside the survey area,whether single component or multi-component measurement channels can be installed according to the practical requirements.While one or more remote reference stations need to be installed outside the survey area at the same time.The effectiveness of the method is tested by numerical simulations,and it is compared with the ordinary methods.The results show that,this new method can not only improve the processing precision of the controlled source responses,but also has the outstanding feature of obtaining both the natural and cultural source responses simultaneously by one field data acquisition,and then improve the efficiency of acquisition and suppress the influence of noise.This method combines the advantages of the natural and the controlled source electromagnetic methods,provides a feasible scheme for the further unity of data processing method for different types of electromagnetic exploration methods.