In this work, we address the scheduling of general maintenance tasks on oil and gas wells and surface facilities, using a mixed integer linear programming (MILP) formulation. The problem involves multitask workorders with precedence relations, comprising both preemptive and nonpreemptive operations, using parallel heterogeneous resources. Crews with different capabilities and work shifts are accounted for. The model introduces novel ideas for expanding the scope of discrete-time formulations. We solve a scheduling problem that includes crew traveling decisions to minimize operational costs and production losses. Different instances of real-world examples are efficiently solved in reasonable times for the industry. Results demonstrate the benefits from optimizing the maintenance schedule of oil and gas production assets and the effectiveness of the solution approach.