PR-1515 – Onsite Mercury Management Procedure – PDO

The Central Oman gas reservoirs are producing mercury for the process facilities (SR-CPP, SNGP, and KGP) with inlet concentrations presently varying between 0.04 to 0.06 mg/Nm3. (milligram/ Normal m3). These concentrations, over the lifetime of the facility, could rise to several hundred mg/Nm3.

Additionally, concentrations of mercury have been found in the non-associated gas processed at some Gas facilities, but to date, these are very low levels.
With natural gas some mercury is produced, the quantity dependent on the reservoir. In addition to metallic mercury, the gas may also contain small quantities of mercury salts and organic mercury.
Normally the mercury remains for the most part in the processing installations and interconnecting pipelines. When maintenance or operations work is carried out the mercury is / can be liberated as, in or on:

• Vapor from steel walls of vessels, pipelines, pig launchers, and receivers;
• As a liquid in cold parts of the process;
• In the gas and on glycol filters;
• As a sludge;
• On pieces of the installation itself;
• In demisters;
• In mercury removal beds;
• As a mixture of condensate, water, glycol, etc.

The purpose of this procedure is to ensure that all personnel, PDO or contract, engaged in maintenance, repair, inspection, and modification activities at facilities where the hazards of exposure to mercury could be possible are informed of the precautions and actions to be taken to reduce or minimize that hazard. The hazards are normally encountered during intrusive activities i.e. maintenance, internal inspection, modifications, etc.