Sense
and Nonsense-
The
Environmental Impacts of Exploration on Marine Organisms Offshore
Cape Breton
by David Lincoln
SUBMISSION TO THE PUBLIC REVIEW COMMISSION
Cape Breton Island, Nova Scotia
for the Sierra Club Canada
2002
Sense and Nonsense-
The
Environmental Impacts
of
Exploration
on Marine
Organisms
Offshore
Cape
Breton
by David Lincoln
Introduction
The Oil and Gas industry proposals to explore and drill for
hydrocarbons offshore Cape Breton are an assault on the senses of man
and marine organisms and even defy good sense. Not only are the
Corridor Resources and Hunt Oil tracts some of the largest tracts
issued in Nova Scotia, they are the closest to shore and both are
adjacent to the unspoiled Highlands National Park. Together these
blocks appear larger than Cape Breton Island itself. Moreover, while
the risk of finding some hydrocarbons next to wells which already had
gas indications are relatively low, the blocks were obtained with by
far the lowest (on a per hectare basis) work commitments. After a
thorough review of the following environmental risks to the natural
resources of Cape Breton it will be up to the Public Review
Commission to decide whether these bargain basement prices justify
these significant potential hazards.
The environmental impacts of the Oil and Gas Industry’s exploration
operations are pervasive. No country or province which has been
exposed to a prolonged history of offshore hydrocarbon exploration
has been left untouched by the inevitable accidents and unforeseen
consequences of the petroleum industry.
The fishing industry is usually the first sector to be impacted by
these exploration activities. This normally occurs when fishermen are
told to remove their boats and gear from an area so that a seismic
vessel can begin generating noises. Although thousands of kilometers
of seismic were already acquired through the 1980’s, hundreds and
probably thousands more are planned by Cape Breton leaseholders. This
cycle repeats itself every few years whenever better technology is
introduced or another company takes an interest in prospects. This
means that fishermen’s activities have been increasingly disrupted
by seismic and drilling activities.
By far the loudest noises generated by the offshore petroleum
industry are those produced by seismic survey equipment. This
equipment is designed to create very loud noises, the echoes of which
reflect off geological strata deep within the seabed and are used to
locate likely places for drilling wells. The sounds were at one time
made by explosives, which could kill fish at a range of some hundreds
of meters, but the almost universal seismic equipment now used
offshore is an array of "airguns".
In assessing the environmental effects of underwater sound, the first
task is to determine at what range that sound would be audible to
marine animals and fish. “Sound exposure
levels of 150 to 160dB are where potential reactions might occur for
large whales and fish. On the Scotian shelf these noise thresholds
are reached at distances of 4.5 to 14.5 km. depending on the specific
location.” (Tsui. 1998) Similar ranges would be expected at the
same depths off Cape Breton.
“Broadband sounds at or above 180 dB would be experienced within
1500 m of the array. Stationary fish would be exposed to this level
or greater for about 20-25 minutes.” Unfortunately, “it is not
yet possible to establish unequivocal criteria for determining the
zone of influence around a noise source. Sound waves are created by
the explosive release of compressed air from an array of air guns
towed behind seismic vessels
(specialized ships), firing every 5 - 12 seconds. Streamers can be up
to 6 km long and are stored on a large winch1”
(Exploring for Offshore Oil and Gas number 2 of a series of papers on
energy and the offshore November, 1998)
Seismic Effects on Fish and Marine Mammals
Experiments on the effects of seismic shooting on abundance and catch
of cod and haddock were conducted in the Barents Sea. The Norwegian
studies (Engas 1993) looked at the effects of an airgun using a
combination of scientific-survey and commercial- fishing techniques.
The fish survey work extended across a circle 40 nautical miles in
diameter (a maximum range of some 33 km from the airgun survey area)
and continued until five days after the seismic work was completed.
It had been supposed that this study would extend far enough and long
enough to delimit the area and time affected by the airgun's sounds
“Acoustic density of cod and haddock decreased over the entire
study area by 45% during the shooting and 64% during the 5 d period
after shooting ceased.
More than 90% of the catch was cod. During shooting, catch in the
shooting area decreased by 60% and catch in the other areas (up to 18
km from the exploration area) decreased by 45-50%. Catch rates did
not recover during the 5 day period after shooting ended. The
longline catch decreased by 45% in the exploration area, but the
decline was smaller with increasing distance from the exploration
area; with no reduction in catch at distances of 16-18 nautical mi.
from it. Catches increased after cessation of shooting.” (Tsui.
1998)
It may therefore be expected that a seismic survey on the shelf will
cause many fish to move some tens of kilometres away from the airgun,
substantially depressed commercial catch rates in the vicinity for at
least several days during and after the survey, though it should not
injure or kill any adult fish (except those very few that approach
within a few metres of the airgun). This degree of disturbance could
be very significant to fishermen working near the survey area.
Indeed, if the fish were forced away from their spawning ground, or
even a prime feeding area, there could be some significant loss to
the resource. Seismic surveys are not innocuous to the fish or the
fisheries.
In a later Norwegian study (Engås 1996), longline “catch was
reduced by 55%-80% within the seismic survey area and there was some
reduction in catch to a distance of 5 Km.” In the same area,
“trawls were made before and during shooting. Cod catches during
shooting were reduced by 79-83% compared to pre-shooting levels
within the
exploration area and within 9 km of it.” (Tsui.
1998). Large fish, both cod and haddock, showed more response to the
shooting than smaller ones did. There was no recovery over the
following few days. Thus, the lower levels after the seismic survey
ended represent a failure of the fish to return following gradual
decline, rather than continued movement out of the study area.
The merits and shortcomings of the Norwegian studies have been
endlessly debated and can never be fully resolved. What has been
missing from these controlled experiments until recently is the
experience and first-hand knowledge of qualified and objective
observers. Since the fall of the Iron Curtain, information has begun
to flow out about the Russian experience with decades of exploration
activity in the Caspian and Barents Seas. These reports differ
markedly from the rather subdued observations in Western Bloc
countries. Dr Stanislav Patin in his 1999 book entitled
“Environmental Impacts of
the
Offshore Oil and
Gas Industry” recalls a catastrophic ecological
situation in the Caspian Sea in the 1960’s. “I was a member of
the Special Government Committee on this issue and witnessed
firsthand the dramatic ecological consequences of the explosive use,
including mass mortality of Caspian sturgeons (up to 200,000 large
specimens).”
This report is not viewed as a serious threat to large groundfish
from modern seismic sources in Canada, but rather as a reminder that
harmful effects of exploration activities have been recorded in many
other countries for years with little coverage from Western sources.
In a fishing experiment on rockfish in California, catch per unit
effort (CPUE) declined by an average of 52.4% when air gun pulses
were emitted at levels of 186 to 191 dB. Skalski et al (1992)
speculated in an area where sound had caused the fish to disperse, a
lowered CPUE might persist.
“With the exception of the California studies of rockfish,
investigators did not measure received noise levels. Thus, it is not
possible to say, with any certainty, what sound levels could cause
reduction in catchability cod and haddock.” However, regarding
dispersal, “There may be some situations in which movement to other
areas will not detrimentally affect the population. However the
safest assumption is that population occupies optimum habitat and
movement away from the habitat is likely to be detrimental, at least
if the animals are displaced for more than a brief period”
(Tsui.1998)
Herring is also relatively sensitive to sound. At 50-1200 Hz its
hearing threshold is about 75-80 dB. Yolk sac larvae (2 day old)
showed peak pressures of 217-220 dB (75- 100 kPa) had detrimental
effects on anchovy. A 50% mortality for 2 day and 4 day old larvae
occurred at this level.
“Peak pressures of 217-220 dB (75- 100 kPa) had detrimental effects
on anchovy. Adult anchovy also experienced swim bladder damage in
this range”. Also “In one study, the fish [Herring] changed
direction and moved away from the source, but schooling behavior was
not affected. The fish reacted to sounds of 144 dB.” (Tsui.1998)
Early life stages of fish are particularly vulnerable. Pulses from
an airgun damaged larvae mainly with a radius of 5m. Eggs of the
anchovy, the most sensitive species experienced some damage at this
distance. (Kostyuchenko 1973). According to the Georges Bank Review
Panel Report 1999, “A consultant to the petroleum industry stated
that fish eggs and larvae are susceptible to seismic damage, and that
seismic pressure waves within a distance of about 1 _ to 6 metres
from the airgun could cause mortality of the eggs and larvae.”
“There are no data on behavioral effects of seismic pulses on fish
eggs and larvae…A small change in the survival rate of larvae can
have a large effect on recruitment to the adult population.”
(Assessment of the Possible Environmental Impacts of Exploratory
Activities on Georges Bank Aquatic Resources. DFO. November, 1998)
According to Patin 1999, “Mechanisms and manifestations of
biological effects of high energy waves of seismic signals on living
organisms can differ. They range from damage of orientation and food
search to physical damage of organs and tissues, disturbance of motor
activity and death. Early stages of fish development – larvae fry
and probably developing eggs – are especially vulnerable.”
Although many complex computer models have been applied to calculate
the radius of mortality in the vicinity of an airgun, the results of
these models should never replace common sense and practical
observations. The fact is that there are no adequately reported
measurements of the sound pressure directly above an airgun. Airguns
are typically towed at a depth of 6m below the surface. This leaves
very little room above the airguns which is not potentially lethal.
Although the oil companies insist that the energy from the airguns is
directed downward, they continue to use spherical models to calculate
dispersal. This suggests that the energy is propagated upwards as
well as downwards.
There are also no reported studies of impacts on organisms located
above the airguns. Perhaps this is because the water above the airgun
has been observed to be forcibly expelled in the air as the bubbles
break the surface. A reasonable person might conclude that survival
of eggs and larvae is limited in this zone, but reportedly the
industry has no data to examine these effects.
The one fact that all researchers can agree on is that there has been
little or no examination of the impacts of seismic airgun sources on
spawning activity. This is surprising, considering that millions of
kilometers of offshore seismic have been acquired in major global
spawning areas such as the coast of Africa, Asia, Russia, Australia
and many other regions. Each of these areas increasingly require
their own versions of environmental impacts assessment and
investigation into fishing consequences. In each area, when questions
are raised about disruption of spawning activity the industry claims
it has no data on these effects. However, it is well known that many
species of fish and marine mammals require auditory signals for
successful mating behavior. In short, propagation of many species may
depend on undisturbed reproductive activity. How many more years will
the Oil and Gas Industry claim that the consequences of
exploration seismic on spawning activity is entirely unknown? The
coast of Cape Breton contains established spawning and nursery areas
for Cod, Winter Flounder, Grey sole, Snow Crab, Scallop, Hake,
Plaice, Halibut, Herring, Yellowtail, Mackerel, Lobster, Sea Urchin
and Shrimp. There is virtually no time of the year when the area is
ice-free when spawning in this critical habitat is not occurring.
Sound Pressure Levels
Confusion over sound reference standards has sparked much debate
recently concerning the potential effect of seismic on marine
mammals. Sound pressure levels are measured in decibels (dB). The
decibel is measured on a logarithmic scale comparing a measured sound
pressure to a reference sound pressure. Since sound reference
pressures differ between air and water, a correction factor of 26 dB
must be added to an air reference when compared to a water reference.
When comparing sound power levels, an additional 35 dB must be added
to an air reference to compare sound power levels to a water
reference to account for the physical differences between water and
air as propagation media. Therefore, approximately 61 dB must be
added to an airborne sound to compare it to a waterborne sound.
Seismic proponents believe that power rather than pressure level is
the more relevant comparison because power levels reflect the change
in energy through a given medium over a specified area while pressure
levels do not.
The effects of these sounds on marine mammals are even less well
known. Detonation of the airgun arrays used in seismic survey has the
potential for structurally damaging marine animals. Whales, primarily
bowheads, have been reported in the scientific literature as showing
reactions of various kinds to seismic surveys at distances of 5 to 10
km, while there is even a report of sperm whales altering their
behavior in response to the sound of a survey some hundreds of
kilometers away. One recent study has suggested that dolphins show a
similar tendency to avoid seismic vessels, though some individuals
were observed within 2 km of the airguns. It does seem, however,
that while such surveys disturb (and perhaps even cause pain to)
cetaceans, possibly reducing their feeding opportunities or exposing
juveniles to predation, they do not directly injure or kill at any
reasonable range.
Dr Rob McCauley from Curtin University in Australia (APPEA 2001
Activity Report) found that the wavelength and amplitude of the sound
produced by seismic equipment are almost identical to the sound
characteristics of humpback whales breaching. The results of the
Curtin University work also indicate that seismic activities are
likely to cause an avoidance response in humpback whales within 3
kilometres from the seismic source.
Obviously this could have a detrimental effect on whale reproductive
behavior. In some instances Dr McCauley found whales were initially
attracted to the sources of seismic activities before swimming away.
Could this behavior potentially cause damage to whales?
It is interesting to note that the Nova Scotia Offshore Area
Petroleum Geophysical Operations Regulations clearly state, “
During a geophysical operation, no air gun shall be test-fired while
the air gun is in the water if there are divers within 1,500 m of the
air
gun. If this is considered a safe distance for humans in the water
when airguns are firing we can only speculate what would be a safe
distance for marine mammals with far better developed hearing?
The DFO has stated (Boudreau et al 1999) that “seismic exploration
has been known to give rise to the following impacts such as:
a
decreased catch rates due to scaring of the
fish;
interference
with fish
spawning
space
conflicts with existing fishing
activities
mortalities
in a number of species and a number of life stages and
,
possibly
change marine mammal
movements
A typical seismic shoot would fire an airgun approximately every 10
seconds. These programs are conducted 24 hrs a day and (for a 2D
program) might operate as much as 70% of the time considering
maintenance and weather. This results in more than 25,000 shots over
a very minimal 10-day seismic schedule. These lines are normally shot
adjacent to each other, so it is likely that some organisms would be
within earshot of these sources for hours, if not days. It is hard to
argue that these impacts are not significant when they occur over a
wide survey area and extend for such periods of time. No one knows
for certain what overall impact these disturbances have on spawning
stocks, survival of eggs and larvae in the near surface, marine
mammals and critical migration routes. All of these issues directly
impact the health and reproductive success of fragile stocks in Nova
Scotia.
Exploration Drilling
Despite industry claims, the companies do not yet know for certain
which type of hydrocarbon (oil, gas, condensate or a combination of
these fluids. will be encountered). Vintage seismic data from the
1980’s cannot accurately distinguish between oil and gas and
geochemistry, if available, is often difficult to interpret. Before
drilling, the companies will conduct a hazard survey primarily to
reduce the chances of encountering shallow gas which could be
disastrous.
Shallow seismic surveys of the upper few hundred meters of the seabed
are often carried out to determine the structure of the sediments and
scan for potential hazards to drilling (e.g., shallow gas pockets).
These hazards will be described in greater detail in the section on
shallow gas blowouts.
The Drilling Phase
Under normal circumstances, the predominant discharges during
drilling, would be the "cuttings"; small chips of rock cut
by the drill in forming the well, and the "muds" used in
the drilling process to cool and lubricate the drill, carry the
cuttings out of the hole and counter-balance the pressure of gas,
when that is reached. These discharges, their fates and their
environmental effects have been the most intensively studied (and
argued) aspect of the offshore petroleum industry's environmental
effect. It has generally been
thought that drill muds cause the greatest harm, other than that
resulting from major accidents.
Aside from the limited amount of information from (mostly
exploratory) drilling in the northwest Atlantic, only Georges Bank
and the North Sea developments offer much documented experience
relevant to the Cape Breton situation.
Cuttings from drilling can have an adverse effect on the benthic
community, the effects of cuttings being substantially greater, at
least when multiple wells are drilled. Beneath the platform, these
effects are mainly due to physical burial of the natural seabed. In
the North Sea early studies showed that major deleterious effects
were confined within 500 m of the platform, where recovery is likely
to be slow. Lesser biological effects, detected as changed community
parameters, extended to 1000 m or, with stronger currents and more
drilling, 2000 m from a platform, and elevated hydrocarbon levels can
extend as much as 4 km down-current.
A much more appropriate environmental effects monitoring program was
designed for the exploratory drilling on Georges Bank in 1981-82. It
included monitoring of barium (a tracer of drilling mud, which
contains a high percentage of barite) at a wide array of stations.
The studies showed (Backus 1987) that the barium concentration in
fine sediment (sieved from samples of seabed sediments) at a
monitoring station 35 km east of the drill sites doubled during the
period of drilling. The same index at a station 65 km to the westward
of the wells (down the residual current) rose by as much as six
times. In the opinion of the scientists involved, the likely reason
that barium increases were not found at still more distant sites was
that the natural sediments at the sampling points chosen were muddy,
diluting any barium-rich mud from the drilling to undetectable
levels.
In the early 1990s, a research team from the Bedford Institute of
Oceanography undertook some field studies around the COPAN platform
on Sable Island Bank. Having noted the crudity of the conceptual
models being used in designing environmental impact studies around
offshore installations, this team had developed advanced sampling
gear that would allow study of more complex environmental mechanisms.
In 1993, following seven months of drilling, this equipment was
deployed on Sable Island Bank and showed that the seabed around the
rig was covered with light flocs, composed of a mixture of biotic
material and drilling wastes. Substantial amounts of this material
were found as far as 2 km from the platform, with some at more
distant stations even the most distant one sampled, 15 km from the
platform though natural flocs have since been seen on Sable Island
Bank and those observed beyond 2 km from the COPAN platform may not
have been drilling-related. (Muschenheim 1995,1996)
In the ocean, our ability to measure change is so weak that gross
damage could be done to resource productivity without anybody being
aware of the fact. If, for example, the groundfish of the Cape Breton
shelf suffered a one-time 25% or even 50% die-off, it is most
unlikely that anyone would ever know for certain that that had
happened since we have almost no ability to even estimate average
rates of non-fishing mortality, let alone to measure their
inter-annual changes. Sustained annual "natural" (i.e.
non-fishing) death
rates could rise from about 20% (their likely normal level) to well
over 30% and yet the possibility of that change would only be argued
over years later when the resulting errors in management caused
another collapse of the fisheries.
Similarly, year-to-year variations in the numbers of young recruits
to each fish stock are so large that a one-time loss of 90% or more
of the young-of-the-year would only be noticed as another "naturally"
poor year. Even a sustained 50% reduction in recruitment would not be
clearly recognizable for a decade or more, no matter how precisely
the numbers of recruits could be documented. Reduction of growth
rates of the fish would be rather more detectable than these changes
in recruitment and death rates, though 10% changes might still pass
unnoticed and, even if detected, it would be all but impossible to
establish the cause of the decline.
Since Nova Scotia's fisheries have annual landed values around half a
billion dollars and overall values to the Provincial economy are
several times higher still, it would be possible for some of these
changes to take a billion or so dollars out of the Provincial economy
annually. Such an effect would most certainly be "significant",
in a social and economic sense, despite remaining undetectable at the
resource level.
Mud and Cuttings Discharges Water Based Muds (WBMs)
Besides their intended constituents, drill muds, both Water Based
Muds (WBMs) and Oil Based Muds (OBMs), often contain high levels of
heavy metal contamination. WBMs, despite their water base, also often
contain appreciable amounts of oil: under some circumstances, it is
necessary to add a "pill" of oil to the circulating WBM and
this is usually left in the mud, gradually being dispersed through it
and ultimately discharged with it.
All drill muds circulate in the well when in use and they are
routinely, re-conditioned and re-used; the cuttings being extracted
from the circulation as the drilling proceeds. In time, however, the
muds become unsuitable for further use and have to be replaced. The
universal practice with WBMs offshore seems to be the discharge,
direct to the sea, of all such waste mud, either as a more-or-less
steady stream or as a short, high-volume "bulk discharge".
Inevitably, some WBM is also discharged with the cuttings produced by
the drilling.
The overall quantities of WBM discharged can be high. While the water
naturally disperses into the ocean, the other constituents represent
substantial contamination. The eight exploratory wells drilled with
WBM on Georges Bank in 1981-2, for example, resulted in some 4000
tons of barite and 1500 tons of bentonite clay being discharged.
The WBM itself, both that lost routinely with the cuttings and that
released in bulk discharges, would contain the many noxious and toxic
components described above. Most of them would only be released in
very small quantities and would be rapidly dispersed in the water
column. They are, therefore, generally ignored in discussions of
the impacts of WBM drilling. Clearly, this is inappropriate and
potentially dangerous, though the wide variety of possible materials
and the lack of study of their effects makes any more detailed
treatment impossible.
Water-Based Mud
The composition of drilling mud may be changed often during drilling
in response to conditions encountered. In practice, this usually
means that mud weight is gradually increased by adding barite and
other chemicals to control the natural pressure increase with depth.
When this happens suddenly, the mud is dumped in bulk and a new batch
is mixed (often with heavier properties in anticipation of increased
pressure). Analysis of the drilling waste scenario data (volume
density and weight) could yield a likely composition. It is indeed
strange that adult scallops are highly sensitive to barite but show
relatively low sensitivity to used water based mud cuttings. This
strongly suggests that the samples analyzed came from the upper part
of the hole where the concentration of barite would be at a minimum.
[Offshore Production, Storage and Transportation Number 3 of a series
of papers on energy and the offshore, November 1998]
Moreover, the time has passed when scientists can simply drag out the
same old reworked oil and gas environmental studies from the North
Sea and Gulf of Mexico showing inconclusive results due to a lack of
pristine base-line conditions. What about the hundreds of thousands
of wells drilled offshore in other regions? Why do these brief
compilations of available data rarely even mention scientific
investigations conducted in other regions?
Furthermore, dozens of organisms have already been subjected to
varying compositions of drilling mud and the toxicity results are
known and well reported. Of 415 acute lethal bioassays lasting 48-144
hrs with 68 drilling muds involving 70 species, 8% showed 50%
mortality (LC50) below 10,000 ppm. The 96-hour LC50 test and the
sublethal tests (Neff 1987) revealed the most sensitive species were
as follows:
Copepods- 5500 ppm in 96 hrs (LC50)
Lobster Larvae- 2000 ppm (increase in larval development by 3 days)
Stage IV 8 ppm (partial inhibition of molting, delayed detection of
food cues) Stage IV-V - 1-4 mm layer (altered burrow behavior delays
in construction) Stage V - 5000 ppm (LC50)
Lobster Adults- 10 ppm Decreased response of walking leg chemosensors
to food cues)
mm
layer for 4 days- inhibition of feeding
behavior
Scallops
Juveniles and embryo's -
Scallop larvae - 49ppm (decreased rate of shell growth)
2 day larvae -100 ppm in 96 hrs (significant inhibition of shell
formation)
Ecosystem Impacts
“There is concern that the routine discharge of wastes during
drilling for oil and gas could impact valuable fishery resources.
Recent studies have indicated that intensive drilling efforts in the
North Sea have caused detrimental effects in adult and larval fish
and benthic invertebrates at greater distances from drilling
platforms than previously envisaged”8.
(Neff 1987)
Abundance of benthic organisms near one N.J. rig site plunged from
8011 animals /sq m. before drilling to 1729 animals /sq m. during
drilling. One year after drilling was completed, the number had risen
to only 2638 animals /sq m. Diversity was also impacted from 70 to
38 species /0.02 sq m rebounding only to 53 species /0.02 sq m one
year afterwards. 8 (Neff
1987)
In the Gulf of Mexico, the benthic fauna is “decidedly reduced
relative to other studies and that the majority of the benthos in an
offshore Ecology Investigation (OEI) study area is composed of two
species, both of which have been documented as precise individuals of
severely polluted environment.” 6(Howarth
1987)
Discharges and Shellfish
Laboratory experiments have shown barium uptake, from
WBM-contaminated sediments and foods, by both flounder and lobster
juveniles but there does not seem to be any evidence for its
biomagnification up the food chain. In the experimental setting, the
contaminants suppressed growth of both species and enhanced lobster
mortality but this was with concentrations of 9 g barium per kilogram
of sediment and a 98 or 99-day exposure concentrations unlikely to be
found offshore for such a prolonged period.
The final fate of the WBM bentonite would, perhaps, be similar to
that of barite. Certainly, its finer grain size should ensure that it
is at least as mobile as the barite and probably more so. Recent
research has shown that scallops are peculiarly susceptible to barite
and bentonite, prolonged exposure to even concentrations as low as 10
mg.l-1 (less than 10 ppm) being fatal, while levels as low as 2
mg.l-1 can affect scallop growth.
What is known is that sediment concentrations in the lowest levels of
the benthic boundary layer of the water column (levels in which
scallops live and from which they draw their food) can be 100 times
higher than those only a few meters above the bottom. In one survey,
around a COPAN site at which drilling had been proceeding for seven
months, tidally-resuspended bentonite was found at detectable levels
even at the most distant station sampled, 8 km from the platform,
though the concentrations there seem to have been around 0.01 ppm and
so should not have been high enough to affect scallops.
All of these firmly established numbers may, however, conceal a
greater problem for scallops. The research to date has, for obvious
reasons, examined the effects of bentonite/barite on adult scallops
finding it to be more harmful than many would have expected. What has
yet to be considered, however, is the impact of bentonite/barite,
lying
on the seabed or suspended in the benthic boundary layer, on settling
scallop larvae ("spat"). Scallops, like most marine benthic
species, have planktonic larvae that must, at a short and critical
phase in their life cycles, select a point on the seabed where they
will settle. While no definite information is available, it is likely
that these scallop spat and their selection activities are more
vulnerable to the impacts of contaminants than are adult scallops.
Thus, it is possible that the bentonite distributed about active
drilling operations would reduce scallop recruitment for some
kilometers around the wells, in the year of the drilling. The degree
of any such reduction can only be a matter for speculation at the
present time.
Recent studies of Scallop impacts from drilling activities on the
Scotian Shelf have been carefully documented. “Much of the observed
growth loss [in scallops] was due to retarded gonad development and
not adductor muscle. Therefore it is likely that drilling wastes
would have more effect on spawning potential (An impact not apparent
in the fishery until reduced recruitment in future years) than on
muscle size.” The net effect might be reproductive loss which could
affect strength of future year classes. (Assessment of the Possible
Environmental Impacts of Exploratory Activities on Georges Bank
Aquatic Resources. DFO. November, 1998)
The benthic boundary layer transport (bblt) and mortality studies on
scallops have the following limitations and are inadequate for
predicting the biological impacts of drilling discharges. Therefore
estimates of lost growth days and safe distances from rigs are
invalid
Scallops
were exposed only intermittently for 12 hrs each day for up to
68
days. Even the hypothetical well was projected to be drilled 24
hrs per day for 93
days
with wastes released on 59 of those days. There is no evidence
that the
benthic
concentrations
of barite would decrease significantly during the brief periods
when
mud
and cuttings were not actually being
discharged.
“The
biological effects predicted apply only to adult scallops (4-5
years
old)”
Known
impacts on eggs and larvae were not
incorporated.
“For
these applications, drilling waste concentrations were averaged
for
the
bottom
10 cm of the water column.” The concentrations obviously would
increase at
the
sediment
water
interface.
No
safe level of barite was experimentally determined for adult
scallops.
Both
the “zero growth concentration” threshold and the “no
effects concentration”
threshold
were estimates not supported by experimental results. Zero growth
occurred at the
lowest
concentration tested (0.5 milligrams/L and could actually have
been much lower.
The
"no
effects" threshold could easily have been in micrograms or
even nannograms per
liter
but
was arbitrarily set at 0.1
milligrams/L
The actual ratio of barite to bentonite averaged over the total depth
of the eight Georges Bank exploratory wells ranged from 47 to 77%
(avg. 66%) 8[Neff
1987]. This ratio also
increases with depth to compensate for increasing pressures.
Increased mud densities result in higher settling velocities.
“The predicted near-bottom concentrations are very sensitive to the
effective settling velocities of drilling wastes. Those at the higher
velocity are about an order of magnitude greater than those at the
lower velocity.” 5
(Assessment of the Possible Environmental
Impacts of Exploratory Activities on Georges Bank Aquatic Resources.
DFO. November, 1998)
“The expected range of settling velocities was estimated using
measured drilling waste concentration profiles around the Copan site
[on Sable Island], but it appears that these did not fully resolve
the dense mats seen in video images. Thus higher settling velocities
and hence near bottom concentrations are possible but considered
unlikely to occur under the tidally energetic conditions on Georges
Bank. If they were to occur on the Bank, near
bottom concentrations and scallop loss could be increased by several
fold above the present model predictions.” 5
(Assessment of the Possible Environmental Impacts of
Exploratory Activities on Georges Bank Aquatic Resources. DFO.
November, 1998)
“As mush as 90% of the discharged solids settle directly to the
bottom. (Brandsma 1980).
The remaining 10% including clay-sized particles and
soluble materials is diluted by the current and dispersed over large
areas8. ”
Furthermore “during the entire [one well] scenario a total of 468
MT of drilling mud and 2569 MT of cuttings are released to the marine
environment. 5 (Assessment
of the Possible Environmental Impacts of Exploratory Activities on
Georges Bank Aquatic Resources. DFO. November, 1998)
“Studies examining the effects of exploratory drilling on the U.S.
portion of Georges Bank found that small amounts of some drilling
muds (in particular the weighting agent barite) had been transported
as much as 60 km from the well site.” 11
[Exploring for
Offshore Oil and Gas number 2 of a series of papers on energy and the
offshore November, 1998]
There is the potential of some suppression of production, through
reduced growth and increased death rates, of this resource within a
few kilometers of each platform while drilling is in progress. The
fate of crabs and lobsters exposed to this level of contaminants are
largely unknown.
Now that it has been shown that drilling eight wells spread
detectable levels of barite over much of Georges Bank, the COPAN
drilling near Sable Island spread flocculant material some kilometers
from the source, Norwegian oil production has affected benthic
communities over some 100 sq km around major platforms and that
background sediment hydrocarbon levels seem to be rising in the
United Kingdom sector of the North Sea, the relevance of such impacts
can no longer be ignored.
Shallow Gas Blowouts
If, as the company’s claim, there is little potential for oil on
the leases then one of the greatest risks to the environment during
the exploration phase is a shallow gas blowout. This is particularly
true if the flow is associated with a condensate discharge which
frequently occurs.
“Shallow gas flows are a critical issue because field experience
and mathematical modeling have shown that it is difficult, and almost
impossible, to control or stop a flow with existing rig equipment
once it begins. Once flow has started, it is almost inevitable that a
blowout will occur. The response time based on field experience is
low or virtually non-existent in many cases. Sufficient time does
not exist in most cases to recognize the
situation, dose the diverter, and begin the kill operation before the
flow becomes uncontrollable2.”
(Adams 1991, World Oil” (May and June 1991)
“Diverter system failures occur at such an alarming rate during
shallow gas blowouts that contingency plans probably should be based
on their anticipated failure rather than an expectation that they
will function effectively. Previously published studies show that
failure rates range from 50 to 70% of all applications.”
“Many operators and contractors now design diverter systems for the
primary purpose of providing time to evacuate the rig. They do not
plan to remain on the rig and attempt to control shallow gas
blowouts”.
With shallow gas blowouts, “Flow outside casing usually results in
severe situations such as a damaged well and rig or platform loss.
Also, flow can exit to the surface through fault planes or around
poorly cemented casing.”
“Cratering occurs when flow outside the casing displaces large
volumes of surface sediment. The eruptive force of blowouts can be
dramatic and has been documented as lifting large boulders weighing
several hundred pounds into the air and dropping them as much as 150
ft from the well site.
Their areal extent can be large. One well had a crater with
dimensions of 1,300 ft x 250 ft x 300 ft deep. However, the actual
depths of craters are not easily determined. Large rigs and platforms
have been lost in craters without any evidence of the rig remaining
at the surface.
“Records show that if a shallow gas blowout does not bridge within
the first one to two days, then the well will probably continue to
blow for an extended period of time, i.e., weeks or months. Some have
continued for years2.”
“Shallow gas flow rates have generally been grossly under
estimated. Bends, bore size changes and flow path discontinuities
produce high particle impact angles and local increases in velocity.
Adams includes a chart condensed from a database of 950 shallow gas
blowouts. Of the 56 rigs listed more than half suffered extensive
damage or the total loss of the rig. (after Adams 1991, How to
Prevent or Minimize Shallow Gas Blowouts (parts 1 &2). World
Oil-May and June.
The truth is that the biological impacts of gas and condensate spills
have been poorly studied until recently. Even the Uniacke gas blowout
which released condensate in 1984 was not evaluated for biological
impacts. Gas blowouts such as occurred in India in 1999 are poorly
reported and not studied in detail. It is ludicrous for the industry
to argue that gas wells have little impact on the ecosystem when they
have not looked carefully at the marine organisms effected and no
long-term studies on productivity or reproductive success following
exposure are known to exist.
Conclusion
In summary, according to the RAP document (DFO 2001 draft) “Any
impacts from oil and gas exploration [documented above] will be
amplified due to the small, shallow, enclosed nature of the
environment and the high biomass and diversity year-round.”
The industry proposals as outlined on their websites are designed
basically to refine existing prospects; they are not shooting in the
dark. Make no mistake, if the seismic programs proceed, drilling will
follow. Such is the nature of these exploration cycles. The companies
are not attempting to find gas in this case; they are only concerned
with how much. They have little concern for the costs to the
fishermen, the communities or the Province as long as they make a
profit.
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"Marine
species need sound for everything they do, and have exquisite hearing,"
says Dr. Kenneth Balcomb. "But now the sounds of ships is ubiquitous in
all of the open oceans." (Photo: Ronald Woan / Flickr) 