1. A computer-implemented method for modifying a drill path of a well, the method comprising: creating a computer model of a formation, the model comprising a plurality of cells; assigning geological property values to the plurality of cells of the model; determining a probability of success for individual cells based on the geological property values; determining a drill path to a target zone within the formation using the probability of success for each cell; receiving real-time data during drilling of the drill path of the well; updating the geological property values in an encountered cell based on the real-time data; updating the probability of success for other cells based on the real-time data of the encountered cell; determining whether to make a change in direction of the drill path based on the updated probability of success for the other cells; and repeating the receiving of real-time data during drilling of the drill path, updating of the geological property values, updating of the probability of success, and determining whether to make the change in direction of the drill path until the drill path is completed.