【作者】 荆磊；

【导师】 江玉乐；

【作者基本信息】 成都理工大学 ， 固体地球物理学， 2011， 硕士

【摘要】 频率域井地电磁方法是指在井中供以交流电在地面接收电磁响应的一类电磁勘探方法,目前正处于实验阶段,其主要用途是圈定油气藏边界等。本文主要研究了井地电磁频率域一维层状介质模型,以maxwell方程为基础,根据互换原理推导出了地下垂直有限长导线电流源的井地电磁响应的解析公式,模拟计算并且分析了地下层状介质中不同场源和不同异常层及其组合的井地电磁响应及其特征。通过不同方法计算均匀半空间模型的井地电磁响应,结果对比表明:该算法技术在提高计算精度的前提下,大大减少了计算量。算例结果表明利用互换原理推导的井地电磁响应公式正确。在均匀半空间的模型里给出各个响应值随发射频率和收发距变化的总体响应特征和随场源深度变化的响应特征。实部值主要集中在一定的收发距范围内,受发射频率的影响较小;虚部值主要集中在中远范围的收发距和较高的发射频率范围内。由于实际的发射频率比较低,达不到虚部极值所要求的频率,所以虚部值会随着发射频率的增加而增加。场源埋深越深,地面的响应值越小但异常特征越明显。浅异常层的异常特征比深层的异常特征要明显。在层状介质模型里给出响应值随异常层的深度变化、异常层的电导率变化及场源长度变化的响应特征。各响应参数对高阻异常比对低阻异常更敏感,敏感程度由大到小依次实部值、虚部值和相位值。在垂直大场源的前提下,异常层越浅响应值的异常越明显。而当场源的埋深与异常层的深度一致时,异常层越深响应值的异常越明显。小场源的响应值所携带的异常信息要比大场源的响应所携带的异常信息多。结果表明实部值、虚部值和相位值均能提供模型介质的电性变化信息。更多还原

【Abstract】 Frequency domain to electromagnetic method refers to a electromagnetic prospecting method which supplies the well with alternating current then receive a kind of electromagnetic response on the ground, now it is still at the experimental stage, its main use is delineation reservoir boundaries etc. This paper mainly studies Wells to electromagnetic frequency domain one-dimensional layered medium model, based on maxwell equations, according to swap principle,we get analytical formula of borehole electromagnetic response to underground vertical limited long wires current source ,and,simulate and analysis the borehole electromagnetic response features of any length and depth of vertical limited line current source of the underground layered medium . Using different methods to calculate the borehole electromagnetic response of the homogenous half -space model ,the compared results show that :this algorithm improves the calculation accuracy premise,greatly reduce the computation. The numerical results show that the electromagnetic response formula derivated from the swap principle is correct.In the model homogenous half space ,it gives each response’ general response characteristics to changes of the launch frequency and the field distance ,and response characteristics to changes of the depth of the field source. In a layered medium model is given the response value of changing anomalouslayer depth,changeinganomalous layer conductivity and the response characteristics of both of that changes. Results show that real value,imaginary part value and phase value all can provide information of electrical change of themodel medium.更多还原