Manage Mercury Risk in Statoil Jakob Nærheim & Ellen Katrine Jensen

2015-09-04 Classification: Internal

Mercury – a Major Hazard

• Elementary mercury is absorbed in the body mainly through inhalation and skin exposure

• It is neurotoxic and may accumulate in the body with prolonged exposure

• Acute exposure may lead to poisoning with an effect that is similar to metallic fever

• Chronic exposure may cause permanent damage to the brain and the kidney

• Pregnant women should never be exposed to mercury

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Mercury in Crude Oil

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IPIECA Mercury management in petroleum refining 2014

The Mercury Complexity

• Mercury may be found in crude oil and natural gas condensate and follows the production flow in different chemical forms

• Reservoirs with sweet crude oil (low content of H2S/CO2) and high temperature or pressure seem to experience the highest content of mercury

• Elementary mercury has been detected in particular in the light fraction of hydrocarbons (C3-C5) and in oil sludge

• Mercury reacts with many metals and also tends to accumulate in process equipment. All surfaces inside process equipment that has been in contact with a process stream with elementary mercury should be treated as contaminated even though mercury is not observed. Mercury may partly be absorbed by the steel piping and equipment.

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Mercury - It’s not a question of if, but when!

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Mercury Removal Unit - MRU

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MRUs typically consist of beds that are filled with an adsorbent. There may be either a surface adsorption, or a chemical reaction, involving mercury in the feed and sulphur in the adsorbent. Once an adsorbent bed becomes spent (i.e. has exhausted its capacity to remove mercury), the bed is taken out of service, and the adsorbent material is removed and disposed of appropriately.

Governance & Information

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Risk Control

1. Identify the hazard: Categorize all installations and facilities according to anticipated mercury occurrence. Categorize the equipment according to likelihood of mercury accumulation

2. Identify jobs with potential exposure

3. Assess the exposure

4. Identify and implement measures to control the risk

− Procedures

− Surveillance

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Qualified Direct Reading Instrument

• RA-915 Light Zeeman Mercury Spectrometer, Ohio Lumex

Data sheet

Stami report 2009/2

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Qualified filter for respirators

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Sundstrøm SR 599 Statoil has test results showing that this filter is working very well for BTX and isocyanates as well.

Statoil Decommissioning Projects

B-11 gas booster platform 2015

2/4-S Jacket 2014 H-7 gas booster platform 2015

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Mercury Emission During Hot Cutting

• H-7:

− Measurement of mercury during hot cutting of process pipes • 41 – 80 μg/m3 (8-12 m from cutting location)

• B-11:

− Measurement of mercury during hot cutting of process pipe • Near field: Increasing to 250 ug/m3 during hot work • Far field (at barrier ~ 10m down wind): 1,3 - 1,6 ug/m3 during hot work

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Biological Exposure Monitoring

• Exposure limits

− Biological exposure limit (12h): • 18 μg Hg/g creatinine / 10,1 nmol Hg/mmol creatinine

− Biological action / assessment value: • 9 μg Hg/ g creatinine / 5 nmol/mmol

• Sampling − 277 samples (100 ind.) offshore

• Results (pre and post samples): − Average: 0,92 - 1,17 μg Hg/g creatinine − Max:1,49 - 6,0 μg Hg/g creatinine

Sum up

• It’s there

• Accumulation

• Sampling

• Splitting

• Hot work

• Waste

• Decommissioning

• Protecting people

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Conclusion

The experience so far in offshore installations is that mercury risk management is possible at work task and equipment level, while well streams represent challenges due to mercury measurements. It is complicated to measure in pressurized systems and multiphase flow, sampling experts and advanced sampling equipment is needed. Availability of sampling points close to the inlet of wells and representativeness of samples are challenging. Technology and procedures exists for measurement of mercury in air and for deposition/contamination of equipment. Qualified direct reading instruments are available, as well as respirators with mercury filters. The complexity of the variables and limitations in sampling differ from the situation in a refinery

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Manage risk of mercury exposure in offshore oil and gas installations

Jakob Nærheim Chief engineer Working environment E-mail jnar@statoil.com Tel: +47 48080237 www.statoil.com

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