Design of a Heating System for Petroleum Pipelines Based on State Estimation and Optimal Control

Deepwater operations in subsea production systems can be critically affected during transient events, such as shutdown periods, because of the formation of hydrates and/or wax deposits (see figure 1). Such formations/deposits can completely block production pipelines, thus requiring different technological solutions to restart production [1, 2]. In fact, during shutdown periods the fluid looses heat to the surrounding environment and hydrates can be formed even at relatively high temperatures, due to the high pressures involved in oil fields nowadays located around 2000 meter below sea level. A possible solution to avoid the formation of hydrates and wax deposits currently applied by the petroleum industry is to use heating protocols on subsea production systems. Typical heating protocols can be used to maintain the fluid temperature above critical levels, as well as to warm it up from the seawater temperature, or from a critical temperature, to a desired thermal profile [3].