Friday, May 02, 2008

Brazil - The New Saudi?

While the oil-fields off Brazil may hold oil in a quantity only beaten by two larger reservoirs in Saudi Arabia and Kuwait, getting it out of the ground may prove extremely difficult. The latest find is called Carioca, in the Santos Basin, 170 miles offshore, and follows the Tupi field, whose reserves are confirmed at 5 - 8 billion barrels. It is thought that Carioca may contain 33 billion barrels of oil and gas, and if this figure is confirmed it will represent the greatest discovery for 32 years. Among much enthusiasm and speculation, it should be noted that 33 billion barrels is about what the world gets through in terms of oil in a year.

Brazil is now the eighth largest consumer of oil in the world, and last year it became self-sufficient in oil production, largely from the state-oil company, Petrobras, exploiting the country's offshore reserves. If these major new reserves can be tapped, then Brazil will become a major oil-exporter since most of its own transportation is run on cheaper ethanol made locally from sugar-cane. It is a big "if", however.

Brazilian expertise in drilling at depths of over 2,000 metres is relatively recent, and to get at Carioca, Tupi and the giant gas-field, Jupiter, it will be necessary to drill down to a combined depth of up to 10,000 meters (6 miles), going through layers of rock and sand, followed by a layer of salt that might be 1.3 miles thick. Under these conditions, the pressure is in excess of 1,000 times atmospheric pressure (almost 8 tonnes per square inch), enough as has been noted, to "crush a pickup truck". The temperatures are high too, at above 260 degrees C (500 degrees Fahrenheit).

In getting the oil out of the reservoirs, engineers will need to cope with the sudden drop in temperature from that hot enough to melt bismuth (used to transport uranium fuel rods) to near freezing-point at the ocean floor, with a likely concomitant and manifold increase in viscosity. The salt-layer under such conditions of pressure and temperature also exhibits some degree of plastic flow, meaning that there is a tendency for holes drilled through it to spontaneously close-up again.

The technological development and investment is presently prohibitive, but with oil at around $120 a barrel and almost certainly set to rise, some think to $200 within a year or so, the incentive increases commensurately.

Related Reading.
[1] "In Brazil, Another Gusher", By Joshua Schneyer:
[2] "Brazil Oil Trapped by 500-Degree Heat, salt Barrier (Update 2)", By Joe Carroll.

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