Выпуск: 2 , Том: 17 , Год издания: 2014

In petroleum exploration, reservoir navigation is used for reaching a productive reservoir and placing the borehole optimally inside the reservoir to maximize production. For proper well placement, it is necessary to calculate in real-time the parameters of the formation we are drilling in and the parameters of formations we are approaching. On the basis of these results, a decision to change the direction of drilling could be made. Modern logging-while-drilling (LWD) extra-deep and azimuthal resistivity tools acquire multicomponent, multispacing, and multifrequency data that provide sufficient information for resolving the surrounding formation parameters. These tools are generally used for reservoir navigation and real-time formation evaluation. However, real-time interpretation software is very often based on simplified resistivity models that can be inadequate and lead to incorrect geo-steering decisions. The core of the newly developed software is an inversion algorithm based on transversely isotropic layered Earth with an arbitrary number of layers. The following model parameters are determined in real time: horizontal and vertical resistivities and thickness of each layer, formation dip, and azimuth. The inversion algorithm is based on the method of the most-probable parameter combination. The algorithm has good performance and excellent convergence because of its enhanced capability of avoiding local minima