Total adds to mercury problem in the Gulf
June 19, 1996
By JAMES FAHN
The problem of mercury contamination in the Gulf of Thailand is more
widespread than previously thought as the natural gas produced from
Total's Bongkot field is also contaminated by the toxic substance.
Questioned about the issue last week, Phillipe Persillon,
Total's project manager for the Bongkot field said, ``It is a real
problem. Our workers on the platform have to wear mercury detection
badges [to monitor exposure to mercury vapours].'
A source at PTT Exploration and Production PLC (PTTEP) confirmed
that gas from the Bongkot field is contaminated by mercury, but said the
level of contamination fluctuates a great deal.
Although Total is the operator of the Bongkot field, the PTTEP
is the largest shareholder in the project with a 40 per cent stake.
France-based Total has a 30 per cent stake, British Gas a 20 per cent
stake and Norway's Statoil a 10 per cent stake.
Because of the geological conditions underlying the Gulf of
Thailand, oil industry executives said mercury contamination could also
pose a problem for future natural gas development in the gulf, including
a Vietnamese concession and a joint Thai-Malaysian zone.
Concern is growing over contamination of the gulf following
reports that increasing numbers of fish are being found with
above-standard mercury levels around the platforms belonging to Unocal,
Thailand's other natural gas concessionaire.
Mercury is a dangerous neurotoxin which builds up in the food
chain. If ingested in sufficient quantities, it can cause birth defects
and damage to the central nervous system.
Unocal officials revealed this week they are currently releasing
around 90 kilogrammes of mercury per year into the sea. On average, the
company discharges roughly 200 parts per billion of mercury, although
this amount also fluctuates a great deal. It plans to install pollution
control equipment to reduce the level of mercury discharged by next
Officials from Total and the Department of Mineral Resources
have so far declined to state the exact scale of the mercury problem
surrounding the Bongkot field, which lies to the south of Unocal's
operations. A public relations officer for PTTEP said the Thai firm is
not ready to comment at this time.
One Total official claimed the amount of mercury being
discharged into the sea is ``very close to zero'. But he asked not to be
Despite Unocal's experience, Persillon said Total was surprised
to discover mercury in the gas pumped up from under the seabed.
``We didn't expect it,' he said. ``We didn't find any mercury in
the test drilling. We only found it when we opened up the pipes for
inspection [once production had started].'
Once brought up from deep underground, the lower pressures cause
mercury to liquify out of the gas, fouling up production equipment.
In 1985, Unocal also discovered the presence of mercury in the
gas from its Plathong field in this manner, and in 1989 the Petroleum
Authority of Thailand temporarily shut down its gas separation plant in
Rayong - which processes natural gas from the gulf - because of similar
Following Total's discovery of mercury in the gas from the
Bongkot field, Persillon said, the company had to install some extra
equipment known as mercury traps in order to collect the toxic
Unocal Thailand President Brian Marcotte told The Nation on
Monday that Total has also installed a hydrocyclone unit, a device used
by Unocal to cleanse mercury-contaminated water pumped up from
underground and discharged into the sea.
Francois Le Coq, the planning department chief for Total
Exploration and Production Thailand, said the amount of mercury released
by Total is likely to be less than that emitted by Unocal because Total
produces less gas than Unocal.
Also, Total's production facilities have only been in operation
since 1993, whereas Unocal began drilling at its Erawan field in 1981.
Total, however, plans to expand its output of natural gas from a
current level of 350 million cubic feet per day (mmscfd) to 550 mmscfd
in two years' time.
Meanwhile, Unocal plans to increase its production from 720
mmscfd to 950 mmscfd by the end of the year. Unocal also has a
concession to develop natural gas resources in Vietnam's portion of the
Gulf of Thailand, which lies southeast of the Erawan Field.
Asked whether gas found in the Vietnamese zone may also be
contaminated by mercury, Unocal Thailand President Brian Marcotte said,
``Because of the geologic environment, it could [be].'
Further south in the gulf lies the Thai-Malaysia Joint
Development Area, where a subsidiary of the Malaysian state-owned oil
firm Petronas and US-based Triton hope to begin natural gas production
by 1999. Petronas and the PTTEP have another joint concession in this
According to David Watkins, Unocal's vice-president of
operations, the trend of volcanic activity underlying the Gulf of
Thailand and much of Southeast Asia could mean that much of the gas
produced in the region contains heavy metals such as mercury and
arsenic, and other contaminants such as carbon dioxide.
The gulf sits atop three geological basins, he explained, known
as the Pattani Basin, the Khmer Basin and the Malay Basin. Although the
three are separate, they share many of the same characteristics: they
are relatively hot and contain relatively large amounts of carbon
dioxide and heavy metals.