By Rhea Wessel
Feb. 27, 2009—For decades, drilling companies have experimented with various technologies to control tools that are part of oil and gas wells, employed thousands of meters beneath the surface. Many of these technologies, however, fail to work reliably considering the high pressure, corrosive environment and high temperatures within the wells.
Now, a Scottish company known as
Petrowell has designed and patented a system that uses
radio frequency identification to communicate wirelessly with valves and other downhole oil well tools. The system can help oil companies extract the maximum amount of oil and gas from fields, the company reports, by depleting the resources in a strategic way.
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With Petrowell's system, glass-encased passive RFID tags are encoded with instructions and then dropped into an oil well.
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Typically, thanks to what is called directional drilling, an oil well can have both vertical and horizontal sections. A company bores down vertically, then turns its drill bit 90 degrees and digs horizontally from the lowest vertical point. A well may reach 3 to 4 kilometers (1.9 to 2.9 miles) in depth and 10 kilometers (6.2 miles) in length. Fluids flow out of the well, but despite that outward and upward flow, businesses can also introduce fluids and small objects into a well's depths from the surface. Well operators often need to send acid down the hole to bore through rock, for instance. The construction of a well and the flow of fluids allow this to occur.
This directional drilling is cost-effective, given the lack of large, untapped reserves remaining worldwide. With wells that extend horizontally, companies can link up small, unconnected patches of oil or gas, and avoid drilling new wells. In other words, the firms can link up six to 10 pockets of oil in a single well, instead of having to drill six to 10 different holes from the surface to reach those patches.
If all of the oil or gas is depleted from the patches located along the vertical area of the well before those along the horizontal section, the company may not be able to extract the maximum amount of oil or gas from the horizontal part, according to Daniel Purkis, a Petrowell design engineer. During the past five years, the company has been developing and recently began selling RFID-based downhole tools that can be operated from the surface to address this particular problem.
According to Purkis, oil and gas flows first from a well's heel—the vertical portion, and the point at which the bit turns 90 degrees. If oil from the heel becomes depleted, the well will begin producing water, thereby choking off reserves from the toe—a well's horizontal section.
"It costs 50 to 100 million pounds [$72 million to $143 million] to drill a well in Angola," Purkis says. "If, after a month, the well produces only water, it's a big problem."