Mercury partitioning in oil and gas production systems - design optimisation and risk mitigation through advanced simulation

Abstract

Operators are increasingly producing fields with challenging operational environments, including fluids with higher concentrations of mercury. Mercury is harmful to personnel and the environment and contaminates most of the production plant that it contacts through physical adsorption, potentially creating hazardous wastes through the operating lifetime and subsequent decommissioning. The assessment of mercury removal locations requires careful consideration at the design stage. Mercury exists in various chemical forms that readily partition between streams in the production process. Mercury partitioning simulations are an essential step in managing the operational, safety, environmental, production and decommissioning risks associated with mercury. Accurate assessment of mercury species during welltests is an essential step towards successful mercury risk management; providing the basis to model partitioning into vapour, liquid, aqueous and solid phases through production. Adsorption modelling is also necessary to understanding the propagation of mercury through offshore and onshore systems, identifying release points to the environment. Only once form, flow and accumulation locations are understood, can the adequate design of mercury removal facilities be confidently completed. Experience in thermodynamic modelling and verification through laboratory research and plant analysis is required to fully understand modelling limitations, capabilities and applications to proposed or existing infrastructure. Changes in inlet stream conditions may affect propagation of mercury through an operating plant thus the influence of predicted conditions through the full life of the field should be considered.