An MILP model and solution technique for the planning of infrastructure in offshore oilfields

The objective of this paper is to propose an optimization model for the planning of infrastructure in offshore oilfields. The proposed model determines the existence of a given set of platforms and their potential connection with wells, as well as on the timing of extraction and production rates. The model includes discrete and continuous decisions along the project lifetime. Discrete variables represent the installation of platforms and wells in each period. Continuous variables are concerned with oil and gas production. Important features of this model are that the pressure in each reservoir is considered and affects extraction globally in the wells, as well as investment constraints. Based on these considerations, the model that represents the infrastructure is a Mixed Integer Programming (MIP) problem that maximizes the net present value that includes the revenues as well as the installation, drilling and connection costs. A disaggregation technique proposed by Iyer and Grossmann (Industrial and Engineering Chemistry Research, 37, 474–481, 1998) is applied to the model that is composed of assignment and planning subproblems. The master problem determines the assignment of platforms to wells and the planning subproblem calculates the timing for fixed assignments. With the decrease in the number of binary variables and with the application of the disaggregation technique, it becomes possible to solve problems of realistic dimension, although investment constraints still require mode efficient solution methods.