1. A method for characterizing a geological formation traversed by a first borehole, the method comprising: a) retrieving one or more set of measured data provided by at least one measuring tool along one or more logged borehole length for one of the first borehole, at least one other borehole or both in order to produce a borehole imaging log; b) selecting depth-defined intervals of the borehole imaging log as training images for inputting in a multi-point geostatistical model; c) determining pattern based simulations for each training image using at least one pixel-based template of the multi-point geostatistical model so as to obtain training image patterns; d) using the pattern based simulation of each training image to assign to each of the training image a corresponding training image pattern; e) constructing from the training image patterns one or more fullbore image log of a borehole wall of the first borehole; and f) repeat steps (b) to (e) through the one or more logged borehole length in order to construct fullbore images from successive, adjacent training images.