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Delivering tomorrow's oil

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By the Total Group

An adventure in technology

In the 21st century, finding and delivering black gold will be a real technological adventure, as we are forced to drill deeper, reach hard-to-access reserves under the sea or ice and refine more complex heavy crudes.

Even with the indispensable development of renewable energies, these moves will have to be made, and they will require considerable investments in terms of money, brainpower and technical know-how.

The first step is to improve the recovery rate in so-called mature fields already in operation. No field's oil is ever completely extracted, even when it's easy to access. The average recovery rate is 30-35%, with a low of 8% for extra-heavy crude oil in Venezuela and a high of 70% for certain fields in the North Sea. Engineers believe they can improve the recovery rate by around 20% in at least a quarter of the world's fields, for an average increase of 5%.

Analyzing fields to flush out oil

Crude oil in natural reservoirs is a little like water in a sponge. It fills in and moves between holes of unequal size and squeezes into cracks in the rocks. Engineers need to know a field well, understand how fluids circulate among the different formations and see where the drill bits penetrate so they can determine where to inject gas or water to drain the formations effectively and flush the oil in the right direction.

For greater efficiency, they can also modify a fluid's chemical make-up. This can mean injecting surfactants to make oil flow more easily or adding polymers to injected water to increase its viscosity so that it can “push” the oil more effectively. Thermal techniques such as steam heating are also used, for example to liquefy frigid, immobile bitumen deposits in Canada.

To achieve the desired result, oil field professionals have to integrate seismic imaging, geological and chemical techniques with data measured continuously as the oil and gas move. More importantly, they need to leverage know-how, knowledge, and laboratory and in situ tests because no two situations are alike. There is no such thing as a one-size-fits-all procedure that works for all oil fields.

The challenges of undersea fields

Operating an offshore field often means dealing with very high temperatures or pressure. Two examples are the Elgin and Franklin fields east of Aberdeen in the North Sea, which were commissioned in 2001 and still produce 150,000 barrels and 13 million cubic meters of gas each day. The water is only 100 meters deep but the reservoirs lie five to six thousand meters under the seabed. This makes for a very high temperature of 200°C (versus 90°C under normal circumstances) and a very high pressure of 1100 bar (versus 200-300 bar ordinarily), along with plenty of corrosive gases.

Many new developments are in very deep water, at depths of up to 3,000 meters, either in the tropics (like the Gulf of Guinea) or close to the Arctic Circle, where the sea is particularly cold. Because people cannot physically work in such extreme conditions, robots have to be used to set up a network of wellheads and complex piping. Although the pipes are sturdy, they become much like spaghetti when more than a kilometer long and require support. They also need to be insulated so that certain substances flowing inside do not freeze.

Heavy oil in Venezuela and Canada

Ordinary crude is a viscous, black liquid. But there are also heavy oils such as those found in Venezuela's Orinico Belt that are more compact and pitchlike, with a consistency close to molasses, and extra heavy oils, like those contained in the solid bitumen deposits in Alberta's Athabascan oil sands region. Last on the list of non-conventional oil is oil shale - essentially rock containing a solid mixture of organic chemical compounds that have not yet been transformed into petroleum. To speed up the natural conversion process, the rock is heated in a furnace or, in some cases, underground.

Horizontal drilling is necessary to extract heavy oils. On the Sincor project launched in 1997 in Venezuela's Zuata region, 220 1,400-meter horizontal wells organized in clusters make up a gigantic web that drains heavy oil from 500 to 600 meters below the surface. The horizontal wells are operated remotely from a control center in Caracas, far from the production site.

In Canada, bitumen is often extracted in open-pit mines. Although the techniques are conventional, they generate environmental concerns due to the vast areas that require reclamation afterwards. In other cases, the oil is deeper underground, mixed with sand and solidified by low temperatures. Steam is injected to liquefy the deposits, raising the twin issues of water conservation and energy use.

No matter what the environmental challenges, Canada's considerable deposits have attracted a great deal of attention because they are geopolitically accessible. Crude oil continues to be a heavily geopolitical resource. Oil producing nations want to hedge their bets and keep reserves underground, where they can only increase in value, so as to gain time in the transition to a post-oil economy. These countries have also developed their national oil companies' activities. NOCs control 75% of oil and gas reserves, while privately owned international oil companies, which account for 65% of investment, control only 25%.

Nov 08

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Petroleumworld News 12/13/08

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