In the literally down-to-earth oil industry the name strikes a frivolous note, but “BrightWater Popcorn” could prove a vital technology in extracting the maximum supply from the world’s oilfields.

In its first large-scale tests at four BP wells in Alaska, it produced at least half a million barrels more than traditional pumping would have yielded. It is now being introduced across the Prudhoe Bay and Milne Point oilfields in Alaska and in several other areas around the world.

It takes its name from tiny particles of a polymer that can be injected with water into oil-bearing rock strata. When they reach a certain temperature these particles expand — just like popcorn — to form a barrier that diverts the remaining water to other strata where there are likely to be richer deposits of oil.

When an oil well is opened up, the pressure in the reservoir is often insufficient to provide an immediate flow, so water is injected around it to flush the oil towards the production well. But frequently the reservoir contains what are known as “thief zones”. These are layers that are more porous than the surrounding rocks and are thus flushed more easily. Once the oil has been pushed out of these zones the water tends to simply flow through the porous rock, leaving a lot of oil untapped and contaminating the flow from the production well.

Popcorn exploits the fact that the injection water is cooler than the reservoir but heats up quickly in these thief zones. When it reaches the appropriate temperature the molecules pop and bind together, blocking the thief zone and forcing the flow of water through richer strata where it pushes out more oil.

The idea for the popcorn effect was originated by Harry Frampton, a BP petroleum engineer, and his colleague Jim Morgan. It was then developed jointly with Nalco, a US-based specialist water treatment company, and Chevron oil. It is now being used in BP joint ventures in Argentina and Pakistan. The polymer formula can be varied to pop at different temperatures depending upon local conditions in the reservoir. “The reservoir itself tells the treatment where to go,” says Frampton.

About 60% of BP’s oil comes from fields where water injection is necessary and BrightWater is one element of the company’s “enhanced oil recovery” programme, which is developing a number of ways to increase yields. Another technique that reduces the salt content of water used to flush reservoirs could increase oil recovery by up to 40% and is now being introduced in several oilfields including Alaska.

But the most ambitious and potentially beneficial, though still at an early stage, is technology to extract CO2 at production wells and reinject it into the reservoir, thus flushing out more oil and at the same time sequestering carbon, which is a favoured method of cutting global emissions.

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