Cross-hole Electromagnetic Character And Imaging

The research on cross-hole electromagnetic imaging technique is on the cutting edge of the advancement of modern geophysics technology. Owing to its special characters, it is paid more attention to by scientists. This paper compared and analyzed characteristics of cross-hole electromagnetic field on different wells and strata by numerical simulation method. Methods and advanced techniques of cross-hole electromagnetic imaging technique were researched into, especially various inversion methods. Based on these results, this paper completed and optimized cross-hole electromagnetic imaging technique by finite element method. The paper studied effects of casing on cross-well electromagnetic logging response. The cased hole buildups the transmission of cross-hole electromagnetic field in homogeneous stratum and heterogeneous stratum. The parameters of cased well affect the change of cross-hole electromagnetic field greatly. Along with the increase of well distance, strength of cross-hole electromagnetic field decreased gradually. Using a method for storing the large-scale sparse matrix with varying band width, Cholesky decomposition, Green function and normalized least square fitting inversion, the paper improved the computing accuracy and efficiency in imaging calculation. The paper did original research on the experiment of cross-hole electromagnetic imaging technique with the experimental model. These experiences will do good to the correlative research in the future.