Methodological Research Of UWB Well-logging

Electromagnetic well-logging is extensively used method in petroleum industry, which could simultaneously measure permittivity and conductivity of underground layers so that could effectively discriminate oil layer from water layer. The measuring depth and resolution of traditional EM well-logging contradict, due to limited bandwidth. By introducing the novel UWB technique into EM well-logging, UWB well-logging suits the trend of acquiring more information in one-step measure. This method could measure the conductivity and permittivity as the traditional methods do, while sensing targets in underground layers.Based on analyses of national and international EM well-logging, UWB and UWB well-logging techniques, this dissertation delves into UWB well-logging method in both theoretical and modeling aspects. In theoretical research, we introduce the standard definition of UWB signal, several UWB forms, derive the slow attenuation of UWB energy with analytical methods and conclude the attenuation principles of EM wave propagating, reflecting in typical medium. FDTD and PML, the algorithms used for modeling, are then introduced. In modeling research, the relationship between amplitude ratio, phase difference and conductivity, permittivity of medium were deduced to support the feasibility of UWB well-logging in acquiring conductivity and permittivity. Another model was built to support the slow attenuation of UWB energy. Finally, models containing targets were built to prove this method could meanwhile measure underground targets through time-domain analysis.UWB well-logging method is still under fundamental analysis. This dissertation has laid foundations for continuous practical work in this prosperous subject, and also provides some guidance and thoughts for the selection of instrument parameters and data interpretation.