Emulation and control of slugging flows in a gas-lifted offshore oil production well through a lab-sized facility

In the oil and gas industry, the gas-lift assist approach is often used in the production wells when the reservoir pressure is insufficient to ensure cost-effective production. However the side-effect of this approach is the often occurrence of regular/irregular large oscillations of the production flow and pressures in the production well system, which is referred to as the slugging flow problem. This instability is mainly due to the casing-heading mechanism. This work investigates the possibility to use a feedback control for stabilizing the production operation without sacrificing the production capability. A lab-sized production well system is constructed in an economic manner. Afterwards, a simple nonlinear model is derived according to physical principles and then verified with the experimental facility. A observer-based state feedback control is designed to handle the potential slugging problem. The developed controller manipulates the openness degree of the production choke based on feedback a number of pressure measurements. The current simulation results showed satisfactory control performances by stabilizing the system operation at some relatively large production rate which is originally open-loop unstable.