A numerical method to optimize use of existing assets in offshore natural gas and oil field developments

Advancements in drilling capabilities and the need to reduce the capital costs of field developments have led to increased interest in the exploitation of existing platforms to drill new wells. Although maximizing the use of existing assets is often advantageous as they offset the high cost of installing new facilities, employing these existing structures is not always feasible because of their limited size capacity, distance from well targets and aging structure. Therefore, a balance has to be achieved between using the available existing platforms or installing new facilities. In this paper, we propose a new numerical approach to optimizing these types of offshore brownfield developments. The approach combines elements of k-means clustering, mixed-integer linear programming, constrained optimization and stochastic perturbation. It accounts for the presence of existing infrastructures as well as the cost of installing new surface facilities, while searching for the field development that minimizes capital expenditure. The optimized field is subject to surface-facility constraints encountered in existing fields, such as platform capacity and asset integrity. The model also uses a detailed well path planning to calculate the optimum drilling path subject to real-world constraints, such as the dogleg severity and maximum drilling reach – thus verifying if the targets can be accessed from the existing assets. Examples based on data from real fields in the Gulf of Mexico, USA are provided to illustrate this approach and discuss the implications for offshore developments.