Oceans, caught between devil and the deep blue sea… (Pun intended!) – XIV

Offshore oil – a benefit to environment or harm? 

There is an old nautical saying which says “tell it to the marines.”  It means a scornful response to an unbelievable story told by somebody.  And there is funny anecdote which claims to be an origin of this saying, although I don’t know whether true.  Around mid-17th Century, during the reign of King Charles II in England, the first official unit of English naval infantry, originally called the Duke of York and Albany’s Maritime Regiment of Foot or in short, the “marines” was formed.  Marines were considered not as adventurous and as hardened as sailors and therefore were deemed that marines were naive enough to believe ridiculous ocean tales.  In fact, the story says King Charles II remarked Samuel Pepys, administrator of the navy of England then, in which he mocked the marines’ credulity in their belief in flying fishes!  Since then, to make fun of an unbelievable story, they say “You may tell that to the marines, but the sailors will not believe it.”  Or shorter version remained over time as “tell that to marines”!

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Duke of York and Albany’s Maritime Regiment of Foot or ‘Marines’

I remembered of this anecdote the other day when I came across an article which claimed that offshore oil drilling could offer advantages to the marine environment.  “Tell that to marines,” I said! 

My last article here dealt with basics of offshore drilling and now more on this debate, whether offshore drilling is indeed a benefit or harm to the environment. 

Offshore drilling operations create various forms of pollution that have considerable adverse effects on marine wildlife.  From surveying ocean floors and identifying areas for potential oil reservoirs, to finally reaching crudes to the refineries; every stage of this supply chain involves a significant environmental risk in it.  Dumping into oceans tons of drilling muds and produced waters which include toxic metal cuttings, such as lead, chromium and mercury, as well as carcinogens, such as benzene and other toxic wastes and hydrocarbons; the risk of oil spills, leaks, and accidental catastrophes; and air pollution generated from the operation of machinery on offshore oil rigs as well as the burn-off of gases, emitting volatile organic compounds (VOCs), nitrogen oxides, carbon monoxide and sulfur oxides – are all environmental hazards of offshore drilling. 

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Pollution from offshore platforms

What are natural oil seeps?

Crude oil and natural gas seep naturally out of crevices in the ocean bed and eroding sedimentary rocks. These seeps are natural springs where liquid and gaseous hydrocarbons leak out of the ocean floor (similar to water springs out of the ground).  In case of water springs, underground water pools feed the springs. Similarly, natural gas and petroleum seeps are fed by natural underground accumulations of oil and natural gas. These seeps result from pressurized hydrocarbon reservoirs that force oil and gas up through fissures to the earth’s surface on the seabed floor where the hydrocarbons escape in the form of oil, tar, and methane-rich gases.

Natural seeps from ocean floors have occurred for millions of years, and our environment has adopted natural means to degrade seeped oil.  These are one of the most significant sources of oil entering the oceans, contributing annually between 4 and 14 million barrels.  Bio-degradation of oils trickled in oceans is a natural process whereby microorganisms use crude as a food source and ultimately break it down to mostly carbon dioxide and water.

arctic oil seep biodegradation_inline

Is offshore drilling is benefiting the environment?

There is a school of thought which claims that offshore oil production has lowered the amount of oil released into the ocean by reducing natural seepage of oil (due to decreases in subsea oil-reservoir pressure because of offshore drilling).  This reduction in seepage was observed especially in areas with active offshore oil seeps, such as California’s Santa Barbara coast of California, one of the most studied offshore oil and gas seep regions over the last 40 years. 

Promoters of this theory emphasize that it is a widely overlooked fact that natural hydrocarbon seeps have a more substantial impact on the marine environment than do oil and gas exploration and production. Geologists believe that over the course of millions of years, more oil has seeped naturally into the earth’s environment than currently exists in all conventional oil reservoirs combined.

The “benefit” theory upholds that, the seepage reductions due to offshore oil and gas extraction have, in some cases, resulted in significant reductions in natural oil and gas seep pollution over the last 40 years.  Californian beaches have become significantly cleaner over the previous 50 years due to offshore oil and gas production, they insist. 

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So what is the truth?

Planning and development department of County of Santa Barbara, on its website, has published a research paper ‘Natural Oil Seeps and Oil Spills’ designed to provide analytical clarification about issues concerning offshore oil and gas production.  The document clears a debate to a large extent.  

It says, from the preceding, it is evident that the effects of natural seeps and oil spills differ hugely. Seeps release large amounts of oil over large areas of the ocean gradually throughout the year. Oil spills release large quantities of oil from a point source in a short time. Natural seeps and spills differ in that seep rates do not, usually, exceed the marine environment’s capacity to digest the oil, whereas spills exceed its capacity. Major spills overwhelm nature’s mechanisms for processing the oil, in the short term. The consequences include severe oiling of shorelines and mortality to organisms that are ill-prepared to live in an oil-soaked environment.

There is some evidence that sea urchin larvae and mussels living in waters near seeps have somewhat higher tolerance for oil than do their counterparts living elsewhere. Some fish and seals can metabolize and excrete small amounts of hydrocarbons. There is also evidence that some species avoid floating oil, instinctively or through learned behaviors. However, neither avoidance nor increased hydrocarbon tolerance would protect the organisms if they were inundated with oil from a major oil spill.

As a generalized concept, it “stands to reason” that extraction could reduce the amount of natural seepage that is possible. However, natural seep mechanisms are complex, and the pressure related “benefit” model does not account for many observations.   Or in simple words, since natural seeps occur because of various complicated reasons, it is difficult to generalize that offshore drilling can reduce sub-sea level pressure reducing natural seeps.   

Ocean waters

References:

  1. The Heritage Foundation
  2. Oceana
  3. SOS California
  4. Exxon mobil website
  5. Santa Barbara County, Planning and development department

Milind Joshi

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