In Situ Mercury Decontamination for Pipeline Decommissioning in the Gulf of Thailand

Abstract

Abstract For offshore decommissioning in the Gulf of Thailand (GoT), Mercury (Hg) has been recognized as a serious contaminant in hydrocarbon streams. Consequently, for PTTEP, as the E&P operator in the Gulf of Thailand, one of the significant environmental and economical issues during decommissioning is the decontamination of Hg in the equipment and pipeline. PTTEP’s decommissioning plan focuses on leaving in situ of subsea pipelines which can be arranged only if Hg contaminated in the pipeline is almost fully cleaned and Hg content is below an acceptable level. Techniques to decontaminate Hg from pipeline and postmonitoring methods are required in the Final Decommissioning Program. Therefore, the research to identify the techniques to measure and remove Hg contents from metal is required. The three innovative steps have been studied including identifying depth of mercury penetration through the pipe surface, developing the technique for in-situ mercury decontamination from the pipeline and finally developing a tool for measuring contaminated Hg content in pipeline before leaving it in situ. According to the study result, the efficiency of the proposed decontamination technique is satisfactory which can remove the major content of Hg in a few hours. In addition, the prototype of tool to measure Hg inside the pipeline was developed and tested successfully. Cleaning process optimization in pilot facilities is currently in progress to finalize the methodology for field application. The proposed methodology and tools are served as "the World First Methodology and Tools". It is considered as green decommissioning to reduce impact on seabed ecosystem and eliminate pipeline Hg contaminated wastes. Also, it is cost effective and potentially creates a new business opportunity for E&P worldwide.