1. A method comprising: correlating a measured log to a predicted log, the correlating by: plotting values of the measured log with respect to an ordinate axis and an abscissa axis, and the plotting in a first pane on a display device of a computer system; plotting values of the predicted log with respect to the ordinate axis and the abscissa axis, and the plotting on the display device of the computer system; selecting an inflection point of the predicted log responsive to a pointing device coupled to the computer system; shifting horizontal position of the inflection point relative to the measured log responsive to the pointing device; changing dip of at least one modeled surface in a structural model based on the relative location of the inflection point; recalculating the predicted log based on the change in dip, the recalculating creates a modified predicted log; and then plotting the modified predicted log.