1. A computer-implemented method for real-time drilling, the method comprising: creating, by a computer system, a model of a formation, the model comprising a plurality of cells; assigning geological property values to each of the plurality of cells of the model; determining a probability of success for each of the plurality of cells in the model based on the geological property values assigned to that cell, the probability of success for each cell indicating a probability that a corresponding portion of the formation has geological characteristics associated with a target zone within the formation; determining a drill path of a well to the target zone based on the probability of success determined for each cell of the model, wherein the well is drilled along the drill path using a drill string communicatively coupled to the computer system; receiving, by the computer system, real-time data from a set of measurement tools coupled to the drill string as the well is drilled along the drill path, the set of measurement tools including one or more sensors and a transceiver unit to transmit data collected by the one or more sensors to the computer system; updating, by the computer system, the geological property values assigned to an encountered cell of the model, based on the real-time data received for a corresponding portion of the formation along the drill path; updating, by the computer system, the probability of success for other cells of the model, based on the updated geological property values of the encountered cell; determining, by the computer system, whether to make a change in a current direction of the drill path, based on the updated probability of success for the other cells; and when it is determined that a change in the current direction of the drill path is to be made, transmitting, from the computer system to the transceiver unit of the set of measurement tools coupled to the drill string, control data for making the change as the well is drilled, wherein the receiving of real-time data during drilling of the drill path, the updating of the geological property values, the updating of the probability of success, the determining of whether to make a change in the current direction of the drill path, and the transmitting of control data based on the determination are repeated until the drill path is completed.