Environmental Effects of Offshore Drilling and Production - IELTS Reading Answers

Nehasri Ravishenbagam

11 min read

Updated On Feb 16, 2026

Want to upgrade your reading comprehension skills? Attempt the questions in the passage on ‘Environmental Effects of Offshore Drilling and Production’ and learn to answer with precision. Analyze the correct answers along with the explanations.

Environmental Effects of Offshore Drilling and Production - IELTS Reading Answers

Types of Questions in ‘Environmental Effects of Offshore Drilling and Production’
IELTS Reading Passage on ‘Environmental Effects of Offshore Drilling and Production’
Answer with Explanation for ‘Environmental Effects of Offshore Drilling and Production’

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The Academic Reading passage on ‘Environmental Effects of Offshore Drilling and Production’ is a reading passage which can help you to elevate your preparation with diligent practice. To achieve the best results in this section, you must understand how to approach and answer the different Question types in the IELTS Reading Module. Ideally, you should not spend more than 20 minutes on a passage. By solving and reviewing sample answers, you get an opportunity to improve on the areas or questions in which you find difficulty in answering.

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Types of Questions in ‘Environmental Effects of Offshore Drilling and Production’

The process of understanding question types is the first step for better guidance and greater assurance while reading the passage. This method would guide you to pick the correct reading approach while preventing unnecessary confusion. The question types which you will encounter in the passage on ‘Environmental Effects of Offshore Drilling and Production’ are provided below.

IELTS Reading Multiple Choice Questions [Q.14-Q.16]
IELTS Reading Short Answer Questions [Q.17-Q.19]
IELTS Reading Table Completion [Q.20-Q.27]

IELTS Reading Passage on ‘Environmental Effects of Offshore Drilling and Production’

You should spend about 20 minutes on Questions 14-27 which are based on the Reading Passage below.

Environmental Effects of Offshore Drilling and Production

1 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.

2 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 51 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

3 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.

4 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.

5 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.

6 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.

7 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.

8 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

9 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.

10 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.

Questions 14-16

Choose the appropriate letter, A, B, C or D.

Write the appropriate letter in boxes 14-16 on your answer sheet.

14 Oil sometimes ‘blows out' of a drilling hole because

The technology has developed too quickly
Special drilling fluids are used.
The surface pressure is not stable
Oil exists under pressure under the ground.

15 Sudden high pressure can be controlled using

Special valves which seal any holes.
Metal clamps and shutters fitted to the rig.
Water to counterbalance the pressure of the oil.
Rubber pressure valves fitted to the rig.

16 Since offshore drilling began in Australia

Oil and gas blowouts have been a major problem
Oil blowouts have occurred occasionally
Most gas blowouts were rapidly controlled.
Gas blowouts have occurred regularly up to the present.

Questions 17-19

Answer the questions below.

Choose NO MORE THAN THREE WORDS AND/OR A NUMBER from the passage for each answer.

Write your answers in boxes 17-19 on your answer sheet.

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?

Questions 20-27

Complete the table.

Choose NO MORE THAN THREE WORDS from the passage for each answer.

Write your answers in boxes 20-27 on your answer sheet.

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 …………………………..

Answer with Explanation for ‘Environmental Effects of Offshore Drilling and Production’

To achieve a higher IELTS Band Score, you need to understand why particular answers are correct. Such analysis would provide you with appropriate explanations to justify why the answer is correct. With this approach, you can build confidence while developing reading skills to attempt different question types within a limited timeframe.

Question number	Answer	Explanation
14	D	Paragraph 1 clearly states that “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.” From these lines, we can infer that oil exists on the surface of the hole, and due to the pressure of any other substances like air or water, it gets blown out. Hence, the correct answer is “D.”
15	B	The first line of Paragraph 2 mention that “modern drilling rigs are also fitted with blowout prevention controls: a complex system of metal clamps and shutter which can be used to seal the hole if unexpected high pressures are encountered.” The phrase ‘metal clamps and shutter which can be used to seal the hole’ confirms that the correct answer is “B.”
16	C	As per the lines of Paragraph 3, “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 the Bass Strait and one in the Timor Sea. The Bass Strait blowouts were all controlled relatively quickly.” From the words ‘six gas blowouts occurred’ and ‘all controlled relatively quickly’, we can deduce that gas blowouts were rapidly controlled because of offshore drilling in Australia. Hence, the correct answer is “C”.

Unlock Answers

17	10 Kiloliters/63 barrels	In Paragraph 2, the last section of the table demonstrates the large single oil spills in the Commonwealth of Australia offshore areas. Hence, the correct answer is “10(63)”.
18	6	Paragraph 2, table and passage 3 both state that “six gas blowouts occurred during that time.” Hence, the correct answer is “6”.
19	Platform oil spills	Paragraph 2, the second section of the table, demonstrates the major cause of oil spillage in the Commonwealth of Australia offshore areas is platform oil spills since the count is 27. Hence, the correct answer is “platform oil spills”.
20	Local food chain	Paragraph 5 states that “this material is diluted rapidly and contributes to the local food chain, without any risk of nutrient oversupply.” From this information, we can deduce that putrescible wastes are discharged into the ocean that supplies the nutrients for the local food chain. Hence, the correct answer is “local food chain”.
21	Solid waste	Paragraph 5 also mentions that “material is diluted rapidly and contributes to the local food chain, without any risk of nutrient oversupply.” Therefore, “all solid waste must be brought ashore.” From the term ‘solid waste must be brought ashore’, we can imply that solid waste is discharged into the ocean, which should be brought on the shore. Hence, the correct answer is “solid waste”.
22	cuttings	As per the first line of Paragraph 6, the “cuttings are sieved (removed) out of the drilling fluid and usually discharged into the ocean.” From this line, we can infer that cutting is another type of discharge that is discharged in the ocean. Hence, the correct answer is “cuttings.”
23	Local and variable	The first line of Paragraph 6 claims that “some benthic organisms may be smothered, but this effect is local and variable, generally limited to within about 100 metres of the discharge point.” According to this information, some benthic organisms suffer due to the discharge in the ocean, but its impact on these organisms is local and variable. Hence, the correct answer is “local and variable”.
24	Heavy metals	There’s a line in Paragraph 7 which conveys that “water-based fluids used in Australia have low-to-nil toxicity to marine organisms. Also, the small amount of heavy metals present are not absorbed into the bodies of marine organisms.” From the phrase, ‘small amounts of heavy metals present are not absorbed into the bodies of marine organisms, we can deduce that heavy metals are toxic additives that are not absorbed by marine organisms. Hence, the correct answer is “heavy metals.”
25	Oil-based (drilling) (fluids)	In Paragraph 8, the first line states that “oil-based drilling fluids have a more toxic component, and discharge to the marine environment is more significant.” Therefore from the line above, we can deduce that oil-based drilling fluids have the most toxic impact on the marine environment since it is a toxic component. Hence, the correct answer is “oil-based drilling fluids”.
26	Gas deposit	The line “water associated with the oil or gas deposit, and typically contains some petroleum, dissolved organic matter and trace elements” from Paragraph 9 confirms that the water is toxic. Other than oil, toxic water is sourced from gas deposits. Hence, the correct answer is “gas deposit”.
27	Background levels	In Paragraph 9 the author claims that “most produced water is effectively non-toxic but, even when relatively toxic, is quickly diluted to background levels.” Therefore, it implies that water is generally non-toxic, but when water is mixed to background levels, it loses its strength. Hence, the correct answer is “background levels”.

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