海底油气藏地质模型的冲激响应  

Impulse response of seafloor hydrocarbon reservoir model

作　　者：汤井田[1] 罗维斌[1,2] 刘长生[1,3] 

机构地区：[1]中南大学信息物理工程学院,长沙410083 [2]长安大学地测学院,西安710054 [3]长沙航空职业技术学院,长沙410014

出　　处：《地球物理学报》2008年第6期1929-1935,共7页Chinese Journal of Geophysics

基　　金：国家“863”计划项目(2006AA06Z105)资助

摘　　要：海洋可控源电磁法(mCSEM)的时间域冲激响应特征可以反映海底油气高阻薄层.本文计算了水平电偶极子源均匀大地半空间,海洋均匀双半空间和海洋四层模型的阶跃响应和冲激响应,提出了瞬变冲激时刻的概念.分析了水平电偶源瞬变冲激时刻与介质电导率的指示关系.对于海底油气高阻薄层宜采用多偏移距同时测量方式,由于在低电导率介质中电磁能量传播得要快,在适当的收发距瞬变冲激时刻会提前到达,提出的瞬变冲激时刻道间变化量可以明确指示高阻薄层的存在及埋深.文中还分析了海水深度对瞬变冲激时刻的影响.由于"天波"干扰,瞬变冲激响应受到一定收发距观测的限制.消除"天波"影响是时间域和频率域mCSEM数据处理的研究热点.The time domain impulse response feature of marine controlled-source electromagnetic （mCSEM） can be used to identify the seafloor thin resistor of hydrocarbon reservoir. The step response and impulse response of homogeneous earth half space, marine double half space and four-layer earth models to horizontal electric dipole source were computed in this paper. A concept of transient impulse time was put forward. The denote relationship between the conductivity of the earth and the transient impulse time of the conductive medium to horizontal electric dipole was analyzed. It is suitable surveyed with multi offsets simultaneously for seafloor thin resistor of hydrocarbon reservoir exploration in that the electromagnetic energy diffused so faster in lower conductive medium, and the transient impulse time can come early at appropriate offsets. The differential of transient impulse time with offsets was calculated, and it was used as a clearly indicator for presence and depth of thin resistor. The effect of sea water depth on transient impulse time was also analyzed. The observation of transient impulse time was limited to a certain offsets for the airwave effect. How to eliminate the airwave effect is now a main research point in both time domain and frequency domain mCSEM data process.

关 键 词：海洋可控源电磁法 瞬变冲激时刻 瞬变冲激时刻道间变化量 天波干扰 

分 类 号：P319[天文地球—固体地球物理学] P714[天文地球—地球物理学]