(1. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083；2. 中海石油研究中心，北京 100027)
摘 要: CSEM有MT不可比擬的優(yōu)勢，得到國內(nèi)外學(xué)者多年的大力發(fā)展，但是，其數(shù)據(jù)處理水平尚停留在1D和2D近似解釋階段。2.5D相對來說更加符合實(shí)際情況(3D)，要想進(jìn)一步發(fā)展該方法，必須開展CSEM 2.5D或3D正演和反演研究。采用有限元法實(shí)現(xiàn)了CSEM 2.5D正演模擬，在驗(yàn)證其代碼有效的前提下，計算了水平地形和地塹地形的電磁場響應(yīng)。采用共軛梯度法實(shí)現(xiàn)了對場值直接進(jìn)行反演的算法。從試算低阻和高阻模型的結(jié)果可知，反演算法精度高，計算速度快，初步達(dá)到了實(shí)用化的程度。
關(guān)鍵字: CSEM；2.5D；正演；反演；共軛梯度
（1. School of Geoscience and Info-Physics, Central South University, Changsha 410083, China;
2. China National Offshore Oil Corporation Research Center, Beijing 100027, China）
Abstract:CSEM is superior to MT to some extent. Plenty of scholars all over the world are developing this exploration method, while the level of processing CSEM data is still staying on 1D and 2D approximate inversion approaches. 2.5D modeling can better simulate the true earth than the 1D and 2D modeling. In order to enhance application of this method, 2.5D or 3D forward and inversion algorithm should be developed. Adopting the finite element method represents CSEM 2.5D modeling. After evaluating the accuracy of the forward code, the electromagnetic responses of one horizontal model and one topography model were calculated. Finally, the conjugate gradient method was used to complete the field inversion algorithm. From the outcomes of response inversion, this inversion approach not only has high precision, but also has a very fast calculation speed. So the inversion code can be used into production.
Key words: CSEM; 2.5D; forward; inversion; conjugate gradient
