Pollution occurs at all stages of oil and gas production.
Liquid, solid, noise, gaseous and aerosol discharges and emissions
are released during seismic testing, exploratory drilling,
extraction and transportation phases. As a result, more than
800 pollutants could enter into the ocean. The contribution
of oil pollution alone is tremendously significant –
over 30 percent of the total oil input into the North Sea
is from the offshore oil industry.
In the Water
While spills and blowouts are major concerns,
drilling muds and
produced waters are dumped into the ocean every day. A
single production platform can drill 70 to 100 wells and discharge
over 90,000 metric tons of drilling fluids and metal cuttings
into the ocean in its lifetime. The cumulative impacts of
drilling a single well have the potential to affect a spatial
area of 1000 metres. To give you some idea, over 400 wells
have been drilled on the east coast of Canada. Almost 60 wells
had to be drilled before Hibernia was discovered. And today,
Hibernia drills 120 wells from its platform.
Drilling muds are released into the ocean on a daily basis.
Drilling muds are essential elements for modern drilling.
They are designed to lubricate and cool the working drill
bit and drill pipe, remove cuttings from the bottom of the
well, control and regulate pressure, stabilize and seal the
sides of the well and prevent accidental blowouts. The volume
of drilling muds ranges from 1000 to 5000 cubic metres for
each well. The toxins released from drilling muds vary with
the composition of the drilling mud and their impact on marine
life depends on such variables as depth, current, substrate
type and wave regimes.
Water-based muds and synthetic drilling muds are used on
Canada’s east coast. These are thought to be less toxic
than oil-based drilling muds, however there are concerns about
their impacts on the marine ecosystem. For example, synthetic-based
muds are water insoluble and do not disperse in water –
they tend to sink to the bottom. The distribution and fate
of these materials has not been extensively studied.
Water-based drilling muds are less toxic then oil-based muds,
but barium and bentonite are associated with water-based muds
and have been detected as far as 8000 metres from a well.
In one case, barium was detected 65 kilometres west and 35
kilometres east of an exploratory drilling site after drilling
stopped. Increases in other trace metals have been associated
with water-based muds. These include arsenic, cadmium, chromium
copper, mercury lead and zinc, however, compared to barium,
their distribution was much more spatially limited.
Produced waters are one of the main sources of oil pollutions
in the areas of offshore oil and gas production. According
to the Russian scientist Dr. Patin, produced waters are responsible
for 20 percent of all oil discharges from the oil and gas
activity in the North Sea region. In Cook Inlet, Alaska, industry
dumps at least 2 billion gallons of produced water into the
Inlet each year. With oil content at 30 to 40 parts per million,
it roughly equates to 70,000 gallons of pure oil dumped into
Cook Inlet each year.
Preliminary research by scientists in Norway shows that produced
water from offshore oil exploration could be seriously harming
cod in the North Sea.
In experimental conditions, chemicals dissolved in waste
water from oil platforms stunted the growth of the fish and
affected their breeding patterns. Scientists at the Norwegian
Marine Research Institute in Bergen found that when cod were
exposed to this solution, their eggs became smaller and spawning
was delayed. It remains to be seen what this means for wild
populations, but this initial research shows there are reasons
for concern and further study.
In the Air
The effects on human and animal health from flaring are significant.
Flaring occurs when gas is burned off to test a well’s
potential, to deal with a well malfunction, or to separate
gas from oil deposits. Research shows emissions from flaring
contain more than 250 toxic compounds, including sulphur dioxide,
a lung and heart irritant, benzene, a known carcinogen, nitrogen
oxide, a known asthma trigger, and toluene, a toxin linked
to reproductive problems. These pollutants can travel 300
kilometres downwind, where they can affect the health of people
and animals far away from the drilling site. A single offshore
rig emits the same quantity of pollution as 7000 cars driving
80 kilometres a day.