CONTINUOUS GEOMECHANICALLY STABLE WELLBORE TRAJECTORIES

摘要

A continuous geomechanically stable trajectory in a subterranean formation is found by calculating at least one reachable stable position relative to a starting position based on geological data indicative of characteristics of the subterranean formation, and iteratively utilizing the calculated reachable stable position as a new starting position. The calculation may be constrained by a boundary including selected distance and direction relative to the starting position, and selected rate of angle change. Within the constraints of the boundary, the possible new trajectories considered may be discretized. The result of the calculations is a three dimensional tree which defines a stability volume. Pruning of at least some branches of the tree may be employed so that not all stable positions have the preselected number of branches, thereby helping to elongate the tree. Either or both of the tree and stability volume are used to select at least one trajectory. For example, the trajectory may be selected from sets of interconnected stable wellbore positions, or based on some other criteria constrained by the stability volume. The trajectory is then used as the basis for drilling a borehole.