The oil extraction process varies greatly, according to the depth at which the oil is found. It can be in the first layers of the soil or even thousands of meters below sea level. This is the case of the mega-reserves discovered in the Santos basin in recent months. The Tupi field, announced in October last year, could add up to 8 billion barrels of oil to the 12 billion in our current reserves. The Pão de Açúcar field, discovered in 2008 and still seen as an unknown by experts, would be, according to what has been commented so far, the third largest field in the world, which would place Brazil among the largest producers on the planet. But it won’t be easy to extract all that oil. First, because these fields are 300 kilometers from the coast – which makes transportation difficult when production is at full steam – and, second, the main reason: the black gold is embedded between rocks located 7,000 meters below sea level. and, what is worse, under a layer of 2 thousand meters of salt. The exploration of this type of field is not a novelty only for Brazil. A lot of money will have to be invested to bring the oil from the Santos basin to the surface. Find out why in the explanations below. B)
GROSS DOMESTIC PRODUCT
With current technology, a maximum of 30% of Tupi’s oil and natural gas will be extracted
1) First of all, you need to find out where the oil is. For this, there is seismic. A ship travels thousands of kilometers towing cylinders of compressed air and fires bursts from time to time. It’s like an explosion, which generates sound waves that hit the ground and come back
2) The hydrophones, towed by the ship, receive the sound waves and decode them, transforming them into images. They are representations of soil layers. Through them, specialists find out if there is oil encrusted between the rocks and, if so, where it is. Then they drill the well to try to get there
3) Drilling starts with installing the BOP in the well. It is a set of valves to control drilling pressure and prevent oil from leaking out. When drilling is complete, the BOP is replaced by a Christmas tree-like structure that controls extraction.
4) At the beginning of the drilling, wide bits are used, about 20 inches (50 cm) in diameter. They are made of steel and, at the tip, have small pieces of diamond, the hardest mineral that exists. During drilling, they are cooled by a special mud, which, in addition to lubricating, takes pieces of rock to the surface, where they are analyzed.
5) Drilling is interrupted to change drills or inject cement, which coats the pipeline, supporting the walls of the well. This is how it is done: the cement goes down the tube through which the drill passes and goes up through the side gaps, forming the wall. Then a smaller drill continues drilling
6) Tupi oil is in a geological layer accumulated before the salt: the pre-salt layer. To get there, the challenge is to cross the thick layer of pasty salt, which moves and can even block the wells. The way out is to make a horizontal drilling. Thus, it avoids drilling several vertical wells to explore the entire pre-salt layer, which is “only” 120 m thick
7) When reaching the oil, a mini cannon is used to cause an explosion between the rocks. Then, gases or liquids are injected to open the formed cracks. It is through these fissures that oil and natural gas reach the well. From there, they rise thanks to the pressure of the natural reservoir.
8) To minimize the difference in temperature between the rising oil (63°C) and the ocean water (2°C), the flexible pipe that connects the well to the production platform has a thermal coating and temperature is controlled by electrical wires and fiber optics. All this to prevent clots from forming, capable of clogging the pipe.
9) Before reaching the continent, the Tupi oil – lighter and more valuable than that currently explored in Brazil – will be processed and stored on platform ships. If the construction of pipelines connecting these vessels to the mainland becomes too expensive, it is likely that transport will be done using ships.