A main public concern about petroleum exploration and production seems to be that a blowout will cause a major oil spill.
Oil often exists in the subsurface at great pressure and, in the early days, when wells were drilled with only air or water in the hole, the oil could rush into and up the hole and ‘blowout’ at the surface.
For reasons of economy and safety, the early oil men soon put a. stop to that practice. Rotary drilling technology developed rapidly, including special drilling fluids with additives to control their density and consistency, and counterbalance the pressure of inflowing oil or gas. Modern drilling rigs are also fitted with blowout prevention controls: complex systems of metal clamps and shutters which can be used to seal the hole if unexpected high pressures are encountered.
There can be no denying that major blowouts still occur, and cause loss of life, as well as severe ecological trauma and economic loss.
AUSTRALIAN DRILLING RECORD
• Total number of incident on offshore facilities over a 30-year period, involving spills 320 litres, or causing injury or damage – 51
• Platform oil spills – 27
• Explosions and fires – 13
• Blowout – 6
• Pipeline breaks and leaks – 2
• Other – 3
• Total number of wells drilled – 1.100
• Total number of kilolitres (barrels) of oil produced – 480,000,000 (3,100,000,000)
• Total number of kilolitres (barrels) of oil spilt – 70 (440)
• Largest single spill in kilolitres (barrels) – 10 (63)
Source: Oil Spills in the Commonwealth of Australia offshore areas connected with Petroleum Exploration and Development Activities. Department of Primary Industries and Energy. Fortunately, the available technology and proper precautions make them very rare events. Since offshore drilling commenced in Australia in the mid-twentieth century, there has not been a single oil blowout.
On the other hand, six gas blowouts occurred during that time: five in Bass Strait and one in the Timor Sea. The Bass Strait blowouts were all controlled relatively quickly; the Petrel well in the Timor Sea flowed gas for 15 months.
It is a comment on improving technology and safety procedures that four of the incidents occurred in the initial decades of offshore drilling. The number of incidents, however, declined progressively over time.
The statistics on oil spills from offshore exploration and production in Australian Commonwealth waters are shown in the adjacent table. The total spill- age, over a 30-year period, is roughly equivalent in size to a large backyard swimming pool (70 kilolitres). The main spills have actually occurred in the loading of fuel onto production platforms; they had nothing to do with the oil well itself.
In addition to the oil spill issue, there are concerns about other discharges from the drilling and production facilities: sanitary and kitchen wastes, drilling fluid, cuttings and produced water. Putrescible sanitary and kitchen wastes are discharged into the ocean but must be processed in accordance with regulations set by the Federal government. This material is diluted rapidly and contributes to the local food chain, without any risk of nutrient oversupply. All solid waste must be brought ashore. The cuttings are sieved out of the drilling fluid and usually discharged into the ocean. In shallower waters they form a low mound near the rig; in deeper water a wider-spread layer forms, generally within one kilometre of the drill site, although this depends on a number of factors. Some benthic (bottom-dwelling) organisms may be smothered, but this effect is local and variable, generally limited to within about 100 metres of the discharge point. Better-adapted organisms soon replace them and storm-driven wave activity frequently sweeps away the material.
Drilling fluid is also discharged directly into the ocean. Most of the common constituents of water-based fluids used in Australia have low-to-nil toxicity to marine organisms. Some additives are toxic but are used in small concentrations and infrequently. The small amounts of heavy metals present are not absorbed into the bodies of marine organisms, and therefore it is unlikely that they would pose a problem for animals higher up the food chain. Field studies have shown that dilution is normally very rapid, ranging to 1,000-fold within 3 metres of the discharge point. At Rivoli-1 well in Exmouth Gulf, the input was chemically undetectable 560 metres away.
Oil-based drilling fluids have a more toxic component, and discharge to the marine environment is more significant. However, they are used only rarely in Australia, and the impact remains relatively local. At Woodside’s North Rankin A Platform offshore Western Australia, the only facility currently using oil-based fluids, the discharge is diluted 2,000-fold within 1 kilometre downcurrent, and undetectable beyond 200 metres either side. In the event of a discovery, the presence of a permanent production facility and the discharge of ‘produced water are additional concerns. Produced water is the water associated with the oil or gas deposit, and typically contains some petroleum, dissolved organic matter and trace elements. Most produced water is effectively non-toxic but, even when relatively toxic, is quickly diluted to background levels.
The impact occurs mainly within about 20 metres of the discharge point, but is observable in some instances for about 1 kilometre downcurrent. Government regulations limit the oil content allowed to be discharged, and the produced water is treated on the platforms to meet those specifications, The discharge points are carefully selected to maximise dispersion and dilution, and avoid any particularly sensitive local environments. Ultimately the best test of the real environmental effect of drilling and producing operations may be the response of the environment to the fixed production platforms. In many areas the platforms quickly become artificial reefs, with the underwater supports of the platforms providing a range of habitats, from sea-bottom to surface, and quickly colonised by a wide range of marine plants and animals.
Choose the appropriate letter, A, B, C or D.
14. Oil sometimes ‘blows out’ of a drilling hole because
A The technology has developed too quickly.
B Special drilling fluids are used.
C The surface pressure is not stable.
D Oil exists under pressure under the ground.
15. Sudden high pressure can be controlled using
A Special valves which seal any holes.
B Metal clamps and shutters fitted to the rig.
C Water to counterbalance the pressure of the oil.
D Rubber pressure valves fitted to the rig.
16. Since offshore drilling began in Australia
A Oil and gas blowouts have been a major problem.
B Oil blowouts have occurred occasionally.
C Most gas blowouts were rapidly controlled.
D Gas blowouts have occurred regularly up to the present,
Answer the questions below. Choose NO MORE THAN THREE WORDS AND/OR A NUMBER from the passage for each answer.
17. How much oil was spilt in the largest accident on offshore facilities?
18. How many incidents were the result of blowouts?
19. According to the table, what was the major cause of spillage of oil?
Complete the table. Choose NO MORE THAN THREE WORDS from the passage for each answer.
|Types of discharge||Source/ location||Comments|
|Putrescible wastes||the ocean||nutrients for the (20)………………|
|(21)…………………….||on shore||no discharging into the ocean|
|(22)…………………..||the ocean||impact on benthic organisms is (23)………………..|
|Drilling fluid||water based fluids||toxic additives, such as (24)…………………not absorbed by marine organisms|
|(25)……………..||impact of toxins on marine environment is local|
|Produced water||oil or (26)……………….||mostly non-toxic which are quickly reduced in strength to (27)……………….|
Garbage In Garbage Out
There are many ways of obtaining an understanding of people’s behaviour. One of these is to study the objects discarded by a community, objects used in daily lives. The study of the refuse of a society is the basis for the science of archaeology in which the lives and behaviour of past societies are minutely examined. Some recent studies have indicated the degree to which rubbish is socially defined.
For several years the University of Arizona, USA, has been running a Garbage Project, in which garbage is collected, sorted out and noted. It began with an arrangement whereby the City of Tucson collected for analysis garbage from randomly selected households in designated census collection districts. Since then the researchers have studied other cities, both in the USA and Mexico, refining their techniques and procedures in response to the challenges of validating and understanding the often unexpected results they have obtained. Garbage is sorted according to an extremely detailed schedule, a range of data for each item is recorded on a standardised coding form, and the researchers cross-tabulate their findings with information from census and other social surveys.
This project arose out of courses designed to teach students at the University the principles of archaeological methodology and to sensitise them to the complex and frequently surprising links between cultural assumptions and physical realities. Often a considerable discrepancy exists between what people say they do—or even think they do—and what they actually do. In one Garbage Project study, none of the Hispanic (Spanish-speaking) women in the sample admitted to using as much as a single serving of commercially-prepared baby food, clearly reflecting cultural expectations about proper mothering. Yet garbage from the Hispanic households with infants contained just as many baby food containers as garbage from non-Hispanic households with infants.
The project leaders then decided to took not only at what was thrown away, but what happened to it after that. In many countries waste is disposed of in landfills; the rubbish is compacted and buried in the ground. So the project expanded its activities to include the excavation of landfills across the United States and Canada. Surprisingly, no-one had ever attempted such excavations before.
The researchers discovered that far from being sites of chemical and biological activity, the interiors of waste landfills are rather inactive, with the possible exception of those established in swamps. Newspapers buried 20 or more years previously usually remained perfectly legible, and a remarkable amount of food wastes of similar age also remained intact.
While discarded household products such as paints, pesticides, cleaners and cosmetics result in a fair amount of hazardous substances being contained in municipal landfills, toxic leachates pose considerably less danger than people fear, provided that a landfill is properly sited and constructed. Garbage Project researchers have found that the leachates do not migrate far, and tend to get absorbed by the other materials in the immediate surrounds.
The composition of landfills is also strikingly different from what is commonly believed. In a recent US survey people were asked whether particular items were a major cause of garbage problems. Disposable nappies (baby diapers) were identified as a major cause by 41 per cent of the survey respondents, plastic bottles by 29 per cent, all forms of paper by six per cent, and construction debris by zero per cent. Yet Garbage Project data shows that disposable nappies make up less than two per cent of the volume of landfills and plastic bottles less than one per cent. On the other hand, over 40 per cent of the volume of landfills is composed of paper and around 12 per cent is construction debris.
Packaging—the paper and plastic wrapping around goods bought— has also been seen as a serious cause of pollution. But while some packaging is excessive, the Garbage Project researchers note that most manufacturers use as little as possible, because less is cheaper. They also point out that modern product packaging frequently functions to reduce the overall size of the solid-waste stream.
This apparent paradox is illustrated by the results of a comparison of garbage from a large and socially diverse sample of households in Mexico City with a similarly large and diverse sample in three United States cities. Even after correcting for differences in family size,
US households generated far less garbage than the Mexican ones. Because they are much more dependent on processed and packaged foods than Mexican households, US households produce much less food debris. (And most of the leaves, husks, etc. that the US processor has removed from the food can be used in the manufacture of other products, rather than entering the waste stream as is the likely fate with fresh produce purchased by households.)
One criticism made of Western societies is that the people are wasteful, and throw things away while they are still useable. This, however, does not seem to be true. Garbage Project data showed that furniture and consumer appliances were entering the solid waste stream at a rate very much less than would be expected from production and service-life figures. So the researchers set up a study to track the fate of such items and thus gained an insight into the huge informal and commercial trade in used goods that rarely turns up in official calculations and statistics.
The Garbage Project’s work shows how many misconceptions exist about garbage. The researchers are therefore critical of attempts to promote one type of waste management, such as source reduction or recycling, over others, such as incineration or landfilling. Each has its advantages and disadvantages, and what may be appropriate for one locality may not be appropriate for another.
Complete the summary. Choose NO MORE THAN THREE WORDS from the passage for each answer. Write your answers in boxes 28-34 on your answer sheet.
THE GARBAGE PROJECT
Studying the (28)……………………of a community is one means by which an understanding of peoples behaviour can be obtained. Researchers running a Garbage Project found from their initial analysis of collected garbage that it was necessary to refine their techniques and procedures because of the difficulties they faced in substantiating some (29)……………………. The investigation involved entering data on a standardised coding form and comparing these results with those from other (30)…………………. The Garbage Project actually came about through courses aimed at teaching archaeological methodology and making students aware of the often unexpected connection between (31)………………………and what in fact happens in reality. This kind of (32)…………………was observed in a sample of Hispanic women who claimed not to have used store-bought baby food, obviously expressing that which would be culturally expected insofar as (33)…………………….is concerned. Their household garbage, however, told another story. It had the same quantity of (34)………………. as the non-Hispanic households with infants.
Look at the following misconceptions about garbage and the list of counter arguments below. Match each misconception with the appropriate counter argument.
35. Certain household items are a major cause of garbage problems in landfills.
36. Western households generate far more waste than others.
37. Germs and bacteria are active and widespread in landfills.
38. Western societies waste many useable items.
39. Harmful substances are widespread in municipal landfills.
40. Paper wrapping is wasteful and causes excess garbage.
List of Counter Arguments
A Toxins are contained in designated sites only.
B Fresh food creates less debris.
C Perishable items are often almost unchanged, even after long periods of time
D It is used sparingly in the manufacturing industry
E Businesses process food debris into other products.
F Household goods constituted a smaller-than-expected part of solid waste
G Disposable nappies make up less than 2% of landfills
H Leachates are confined to surrounding areas.
I It is used far more efficiently by manufactures these days.
J Paper constitutes 6% of landfill.