This paper presents an approach undertaken by PETRONAS Carigali Sdn Bhd, an E&P subsidiary of PETRONAS in selecting, optimizing and installing a mercury removal system in one of its operations in Malaysia. It focuses on the treatment of the raw condensate stream that was noted as having much higher mercury content as compared to the gas stream. Since the experience in mercury removal in raw condensate is limited, this paper also presents the work done to mitigate the risks and improve the removal performance. The paper shares the initial performance of such system and the issues faced to sustain its long term effectiveness.

Through operation surveillance, mercury was observed to be present in the hydrocarbon delivered by PETRONAS Carigali to its downstream customers. A Mercury Removal Project was initiated in March 2005 to treat and remove the mercury from the hydrocarbon. The Project was conducted on a fast track basis. Adsorbent technology was selected following a thorough evaluation that includes carrying out performance tests in the laboratory. The project is among the first in the world to remove mercury from raw condensates. (The gas was not treated after the data established that the mercury content in the gas meets specifications).

The project was completed in stages with the first system installed in March 2006, and the second in July 2006. The results show that the units managed to remove mercury from the condensate with more than 95% efficiency. The project demonstrated that the treatment of mercury could be done upstream prior to exporting the hydrocarbon liquids. It is an approach that should not be ruled out in the gas processing value chain whether for reasons of risks mitigation or value improvement or both.

Mercury is a natural occurring element and could be present in varying concentrations and of various species in oil and gas fields. Mercury is not only hazardous to human health and the environment but could also attack equipment components that have mercury reactive materials, leading to a potential catastrophic failure to the plant.

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