Techniques for determining trajectories for a plurality of wells while avoiding collision between wells are presented. The techniques can include determining a zone of uncertainty for individual wells of the plurality of wells, determining a minimum separation factor for individual wells of the plurality of wells, determining a gradient of a separation factor for at least one pair of wells of the plurality of pairs of wells, updating a nudge position for at least one well, and providing nudge positions for the individual wells of the plurality of wells.