17. Optimal Planning and Scheduling of Offshore Gas Facilities Capital Investment and Operation

A. VECCHIETTI; A.S: CULLICK; S. VASANTHARAJAN

Dalla, TX (USA)

Conferencia; AICHE 1999 Annual meeting; 1999

AICHE

This paper presents a multiperiod mathematical programming model for the optimal planning and scheduling of multiple offshore gas field developments. Given a long term plan horizon, the configuration of wells, reservoirs, fields, well platforms, production platforms and available markets, the model determines the hierarchy of reservoirs, fields and wells to be exploited, their startup times, and the operational policy. The model also determines the production flow of wells, fields and reservoirs, and the well and production platform capacities. The objective function is the maximization of the net present value (NPV) which is calculated by adding the discounted investment cost, the operating and maintenance expenses and, on the other hand, the revenues obtained from the sales of the gas to the markets. Since the equation representing the gas rate production of the wells is nonlinear, the problem formulation corresponds to a Mixed Integer Nonlinear Programming (MINLP) problem. The size of the problem is very large involving thousands of equations and constraints that make the MINLP model intractable. The original MINLP  was transformed into a Mixed Integer Linear Programming (MILP) problem by piecewise linear interpolation of the nonlinear equations. We proposed an algorithm whose solution is as good as the original MINLP. The results obtained after solving one example are shown.