Oil now makes the world work. At the moment we can’t do without it. But the oil that was found on land has run out in the places where it was easiest to drill. So, over the years, exploration has been done in places that are harder to work. There are, for example, great oilfields being worked in very cold lands of the north. These Tundra lands, as they are called, include Alaska, northern Canada and Russian Siberia.

These are remote places and the oil has to be brought thousands of kilometres from where it comes out of the ground to places where it can be processed (oil refineries). There is always a danger that these pipes will fracture or that terrorists might try to blow them up. Many of these have to run above ground because the ground is frozen. If a part of the pipe fractured, oil could spill out and damage the environment. So these pipes have many valves along their route which shut off the pipe automatically if there is a fracture.

But most new exploration is in the sea bed. Working the sea bed has its own special problems. You many be working in depths of thousands of metres of water and the sea may experience stormy weather. This makes drilling much harder and getting the oil onshore much more difficult. The drilling rigs are usually enormous, more like blocks of offices in size, and the pipes that connect the rigs to the land are also large.

Just like pipes on land, these underwater pipes have valves along their length that automatically shut off the flow of oil if there is a problem.

The most challenging part of the operation is drilling the well. (See blowouts on earlier pages). The biggest challenge arises when there is a problem with the oil well head, that is where the oil comes out of the ground. There is a valve here, too, (the blowout preventer valve) but if that valve does not work, then it is very hard to shut off the oil.

One way is to squeeze the pipe closed. You get a (very) large pair of pliers, as it were, and simply squeeze the pipe shut. It is called crimping and the ‘pliers’ – called ‘rams’ – are built into the valves.

Oil in the sea
The problem with oil spilling out of an undersea well is that it is one liquid flowing into another. It is much harder to capture liquids once they start to flow into one another. What you need to know is that oil is a mixture. Some of the mixture is very runny oil, some is much thicker. When it comes out of a well and goes into the ocean, the thicker stuff actually forms into balls and sinks to the bottom where it can form a sheet and smother anything living on the sea bed. Heavy oil that forms balls may later wash up onshore where it is known as tar balls. You may have seen some on a beach. Some is lighter than water, so it floats on it. So you often have two problems to deal with.

To begin with, you have to deal with the lighter oil. That is because it can flow about so easily and the more it flows, the harder it is to deal with.

Light oil is like dirt, it does not mix with water. You might think that is a good thing. It rises to the surface and forms a sheet. You might think it is then relatively easy to put a boom (a long sausage of floats) around it and send in a ship to pump it all off the surface. That is certainly what people try first. But if there is stormy weather and a rough sea, the oil splashes over the booms. As the oil spreads out, the longer the booms have to be. So placing booms is a race against time, while hoping for calm weather.

You can make oil mix with water and become harmless. Think of dirt and your washing machine. You add a detergent. This chemical dissolves in the washing water and it attracts the dirt, so pulling it off your clothes. It also keeps it spread out in the water, so it can be washed away. The tumbling of the washing machine helps the detergent mix with the dirt. So another way of dealing with an oil spill is to spray it with detergent. The sea is always choppy, so it acts like a natural washing machine. But a giant oil slick needs a vast amount of detergent sprayed on to it.

If luck is with you, the oil will be blown offshore and it will break up naturally. The problems increase greatly if the wind or sea currents push the oil slick on to land or carry it along the coast, for then it will pollute a much larger area. When it reaches the land you have some very sticky black slime on every particle of sand, every piece of seaweed, every rock and so on. It is almost impossible to clean off, and may take decades to clean itself.