An integrated MILP model for optimal planning of multi-period onshore gas field gathering pipeline system

•An integrated MILP model for multi-period gathering pipeline system is developed.•Multi-period, 3D terrain and hydraulic characteristics are considered.•A two-layer non-uniform discrete grid is proposed for MILP model and ACO.•A piecewise approximation method is employed to eliminate the nonlinear terms.•Three real-world case studies are given to illustrate the method’s practicality.