Study Details Management of Mercury for Production Facilities

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper OTC 31465, “Management of Mercury Offshore for Onshore Production Facilities,” by Mohamed Sopiee Saaibon, Zainab Kayat, and Fatimah A. Karim, Petronas. The paper has not been peer reviewed. Copyright 2022 Offshore Technology Conference. Reproduced by permission. The objective of the complete paper is to provide an approach to mitigating the adverse effects of mercury found in production fields. It includes an evaluation of treatment-facility requirements and suitable technologies for production fields and facilities. The evaluation covers assessment of pipeline integrity and managing unexpected increases in mercury content to ensure that mercury removal units (MRU) can treat gas within design specifications. Introduction Mercury is present as a contaminant in many oil and gas reservoirs; southeast Asia is a well-known for high concentrations of mercury. The presence of mercury poses a threat to the operator’s integrated upstream value chain. The primary concern is exposure of mercury to downstream aluminum heat exchangers for liquefied natural gas (LNG) production. The production lines and risers, although made of carbon steel, are exposed to integrity threats and, consequently, risk deferment of production. Initial Problem Concerns regarding mercury’s presence in hydrocarbon processing systems arose when substantial liquid mercury was detected at the operator’s downstream onshore LNG plant at levels three times beyond the design of its existing onshore MRU within the plant. Such high mercury concentration in feed gas was not expected because the wells had been operational for only 1 year. Immediate measures taken to handle these high quantities of mercury to protect the plant and its aluminum equipment included the following: - Reduction of feed-gas intake and production slowdown - Closing of wells with high mercury content - Mixing of that gas with low-mercury gas - Preparation for MRU adsorbent changeout No method exists to predict mercury production, and thus mitigation and equipment design—particularly that of an MRU across an integrated oil and gas production system—cannot be based on subsurface production data alone. A holistic approach to determine reservoir mercury concentrations from geology by on onsite sampling and mapping, from the wellhead to the production facility along the pipeline to the plant, was initiated.