¿ìè¶ÌÊÓƵs and engineers are replacing soldiers in the Gulf in a campaign to stem the environmental damage wrought by war. Their enemy is oil, either burning at wellheads and storage tanks, or lapping the shores of Saudi Arabia.
The most immediate threat to health and the environment comes from the large plumes of smoke billowing from burning wells. The cloud of soot has not, as feared, risen high into the atmosphere where it could disrupt the climate across large parts of tropical Asia. But it does stretch across some 15 000 square kilometres of the Gulf, hiding the sun and hindering air traffic in and out of Kuwait City.
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According to one Kuwaiti estimate, some 6 million barrels of oil a day are going up in smoke. This is four times the amount Kuwait exported daily before the war. To put out the fires, the Kuwaiti government has turned to three companies, all based in Houston, Texas. Red Adair, the best known, has been joined by Wild Well Control and Boots and Coots. They are due to start work in Kuwait within a few weeks. The three companies will send two fire-fighting teams each, but their resources are dwarfed by the size of the problem. More than 500 wells are ablaze in Kuwait. At the normal pace of putting out such fires, it will be years before the final flames are quenched.
There are two basic ways to bring a blazing oil well under control. In the first method, the flames are extinguished by depriving them of oxygen, and the well is capped from above. The second way is to cut off the supply of oil and gas from below, preventing it from feeding the fire on the surface.
The first approach is most common. But the task is complicated by the degree of damage inflicted by the Iraqi saboteurs. In some cases they used explosives to blow up the wells more than 10 metres below ground level, says George Hill, a fire fighter with Wild Well Control. In other cases, the explosives did not go off and remain attached to the wells.
To cap a well, says Hill, it is crucial to find a piece of unbroken well pipe. This is particularly difficult in wells that have been blown up.
On an inspection trip to Kuwait, Hill’s colleagues found flames at a number of wells, pouring out around concrete ‘cellars’ that contain many of the wells’ control valves. In such cases, the first task will be to break up this block of concrete, which is embedded two to three metres into the ground, haul it away, and dig down to undamaged pipe.
Once the pipe is exposed, Hill and his colleagues fight fire with fire. They manoeuvre a large drum filled with dynamite or plastic explosives next to the fire and detonate it. The blast consumes all the oxygen in the vicinity, depriving the flames of vital air. If all goes well, when the smoke clears, the fire is out.
But the tensest moments of the operation are still to come. Oil and gas continue to gush from the wellhead and the fire fighters must take extreme care not to create sparks as the well is capped.
In one alternative to explosives, some fire fighters surround the flames with a metal tube held several feet above the ground. Air rushing in below the tube feeds the fire. So when that area is flooded with nitrogen, the fire dies.
New technology has made it possible to cut off a fire’s supply of fuel by plugging the well thousands of metres below ground. Two US companies have developed a technique to drill another shaft, known as a relief well, directly into the side of the original shaft. Concrete, poured into the hole, then seals the well for good.
Drilling a relief well can take more than a month, which is one reason why fire fighters avoid using them. ‘When we get called in, it’s generally a lost cause at the surface,’ says Bob Waters, who founded Tensor, a company which specialises in drill navigation. At Wild Well, Hill says his colleagues will have to take a closer look before they decide whether many of the fires will require relief wells.
The biggest problem with drilling relief wells is finding the target shaft at great depths. Engineers have to drill deep because it is the weight of an enormous column of drilling fluid that stops the stream of oil and gas rising up the relief shaft from below. If the relief well is too shallow, the pressure could blow the fluid right out, creating the risk of another fire.
To further control the pressure and force the gas and oil back down the wellbore, drilling fluid is often weighted down with barium salts. It can reach twice the density of water, says Kuckes.
Even a well that is drilled straight down into the earth will drift about 1 degree off the vertical line, says Arthur Kuckes, president of Vector Magnetics in Ithaca, New York. So at a depth of say 3000 metres the well could be anywhere within a 50-metre radius of a point directly below the wellhead. Without a way of finding it, says Bob Waters, ‘you could circle out there for years and never find your well.’
Kuckes and Waters locate wells with electricity. An electrode carrying a few amperes of low frequency alternating current is manoeuvred into the relief well. The current runs to earth along the ‘blowout’ well’s casing; a far better conductor than the surrounding soil or sand. This current generates an electromagnetic field which can be detected by a probe in the relief well, within 60 or 70 metres, says Kuckes. Special drilling equipment can then steer the relief well towards its target.
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Saudis prepare to clear oil from troubled waters
The largest oil slick left by the war has stopped moving south along the Saudi coast but oil from it continues to come ashore. The slick now lies just north of Abu Ali island. It is being prevented from continuing its southeastward progress by the island itself and by unseasonal winds from the northeast. Northwest winds are more usual.
Information about the slick has been smothered by the secrecy of the war that caused it. Aerial and satellite images of the area have been rare and most have been kept from public view. A task force of experts from the US, Britain and Canada that has toured the Gulf has been discouraged from talking about the slick.
Saudi officials now estimate the main slick’s size to have been between half a million and 2.5 million barrels, according to scientists back from the Gulf. That is far less than reports that originally put the slick at over 10 million barrels, but much more than the quarter of a million barrels that spilled from the Exxon Valdez into Alaska’s Prince William Sound in 1989.
The oil now extends from Abu Ali island some 40 miles northwest, close to the town of Ras al Saffaniya. It is no longer a single slick, but has broken up. Most of the oil lies offshore in shallow water, says Ron Atlas of the University of Louisville, who has conferred with scientists at the scene. Some oil, however, has invaded beaches and mud flats.
Initial reports that the spill has caused an ‘environmental catastrophe’ are probably exaggerated, says Edward Owens. Owens is a coastal geologist with a Canadian company, Woodward Clyde Consultants, who has studied oil spills for two decades and has interviewed scientists who have visited the scene. He says ‘Much of the concern is aesthetic, not ecological.’
Features of the Gulf environment may blunt the damage. Oil floats longer in the Gulf because of the water’s high salinity, which ranges from 41 to 60 parts per thousand compared to a worldwide average of 30 ppt, says Owens. Intense sunshine and high temperatures in the area hasten the evaporation of the oil’s more volatile fractions, and a high count of bacteria which digest organic matter, should help speed its breakdown as well.
Dissolution of the slick began as soon as it hit the water. Oil droplets are dispersed by wave action. And although most droplets resurface, some get chemically dissolved in the water. This dissolution is the principal source of toxic chemicals, such as xylene and toluene, that damage plant and animal life.
As the oil floats, sections of it have emulsified, mixing with water droplets to form a ‘mousse’ that is 70 per cent water. Reports from the Gulf describe some of this mousse lapping near the shore. At other sites, the oil is still black and undiluted. According to Vice Admiral Martin Daniel of the US Coast Guard, some of the slick has now formed a hard, ‘asphaltine’ shell that has resisted mechanical dispersal.
Much of the Saudi coast consists of mud flats and sandy beaches. These conditions should make cleaning up easier than it was on the rocky, convoluted shoreline in Alaska, says Owens, who helped organise the Alaskan rescue operation. Earth-movers can simply scoop up the oil.
Officials at Saudi Arabia’s Meteorological and Environmental Protection Administration (MEPA) are assessing the use of biological methods to help degrade the oil. In Alaska, clean up crews from Exxon say bacteria helped degrade, or ‘eat’, oil on rocks, the ground and in shallow water, a claim independent scientists confirm. All that was needed was the addition of nitrogen and phosphorus, nutrients that increased bacterial populations.
Experts differ on the effectiveness of bacterial degradation of oil, however. Bacteria work best on thin films of oil, says Owens, and the Gulf slick may have passed this stage by now.
Moreover, bioremediation has not been shown to be successful on oil in the open ocean, but rather in protected bays and onshore, says Rita Colwell, a microbiologist at the University of Maryland.
If the oil along the Saudi coast is not removed soon, it will become as dense as sea water and sink, making it hard to reach with bacterial Sand blown onto it has already made it heavier.
Equipment has now been move into place to start cleaning up the slick. The International Maritime Organization is coordinating international efforts. Mechanical barriers are reportedly being readied at the south end of Abu Ali island to seal off a narrow stait through which oil could escape and resume its migration south.
Near at least one desalination plant, a pit has been dug into which clean seawater has been diverted as insurance should oil breach protective barriers around the plant’s intake pipes. Saudi workers are rescuing oil-covered birds and trying to clean them.
But efforts to muster cleanup crews have been hampered because of a lack of ready cash, equipment and labour. ‘Human health and safety is a more serious matter now,’ says Owens.