A Robust Surveillance and Optimization Workflow for Offshore Gas Lifted Wells

Abstract In this paper we present an automated surveillance and optimization system for gas lifted wells. The system integrates flow instability diagnostics, steady-state flow models, and transient multiphase flow models to provide engineers and operators with a complete solution for well flow surveillance and optimization. This system is a significant enhancement to the Gas Lift Optimization Workflow (GLOW™) that was developed and deployed to multiple assets including a platform in the Gulf of Mexico. The system calibrates the models to match flowrates and pressures from multiple well tests. The calibrated models are then used to produce operational maps that provide accurate and robust flow instability recovery recommendations and stability constraints for optimization routines. We will show an example implementation of the system for a gas lifted well from an offshore platform. In most cases, the calibrated transient flow models accurately replicated the amplitude and frequency of pressure and flowrate oscillations for two types of flow instability: casing heading and hydrodynamic slugging. We also compare transient flow and steady-state models, and discuss the use of both to maximize computing efficiency. The developed system uses multiphase flow transient models, in an automated way, to produce operational maps that can aid either asset staff or the GLOW™ system to optimize production while steering away from unstable flow. In summary, the system provides a comprehensive, robust, and integrated set of tools for the surveillance and optimization needs of asset staff.