21 May 2004
21 May 2004
The US Department of Energy (DOE) has developed a new composite drill pipe that is lighter, stronger and more flexible than steel.
The new composite drill could, according to the DOE, significantly alter the ability to drain substantially more oil and gas from rock than traditional vertical wells.
With much of the nation's ""easy-to-produce"" oil gone, many U.S. companies are looking for lower cost ways to recover oil and gas that may have been bypassed when the fields were first opened.
Some of these companies have turned to the combination of flexible drill pipe and ""slimhole"" (small diameter) drilling to re-enter older, vertical wells and drill horizontal offshoots into oil- and gas-bearing formations that previously were deemed uneconomic.
Horizontal wells encounter several hundred, maybe several thousand, feet of a rock bed, allowing them to drain substantially more oil from the rock than traditional vertical wells. But the sharp curvature of a typical short-radius re-entry well – where the drill pipe arcs in a 20 to 80-foot radius – can create stress and fatigue damage that decreases a pipe's life and reliability.
The flexible composite drill pipe overcomes this problem. Although more expensive than a traditional steel pipe, it can remain bent for extended periods of time without suffering fatigue damage. DoE claim that fewer pipe failures occur and less pipe is needed because of the shortened radius. The drill pipe can also be reused in multiple wells significantly reducing drilling costs.
The composite pipe could bring new life to thousands of idle wells drilled in the early 20th century. In many fields, oil-bearing formations that weren't previously considered economic lie 100 feet or less below the base of the vertical pipe. Using short-radius drilling to bore a horizontal well into these formations could bring many of these older wells back into production without the environmental disturbance that drilling new wells from the surface would create.
“This is another example of the technology breakthroughs in the arena of domestic energy production being carried out by our Office of Fossil Energy,” said Secretary of Energy Spencer Abraham. “To reach and recover untapped domestic oil and gas reserves, we must have the ability to inexpensively drill highly deviated or horizontal holes.”
Developed under a four-year, $3.6 million cooperative agreement managed by DoE's National Energy Technology Laboratory, the new drill pipe could be the next major technical achievement emerging from the government-industry natural gas research program.
The composite drill will be used by Integrated Directional Resources, Lafayette, La., and is the first commercial order for the device composed of carbon fibre resins. Since the composite pipe is more flexible than steel pipe, it can better withstand the stress and fatigue associated with drilling short-radius horizontal holes.
The drill pipe has been successfully field-tested at two Oklahoma sites. Through the use of the new drill at one previously producing site, the well was drilled another 1,000 feet where it struck an oil-bearing zone. Another test allowed the composite drill to punch a 60-foot radius, 1,000-foot lateral through hard sandstone from a shallow well in a successful search for gas.
In deep drilling, the weight of the drill pipe is an especially important factor. The lighter the drill pipe, the less torque and drag is created, and the greater distance a well can be drilled both vertically and horizontally. Also, offshore platforms have weight limitations which also can lessen the distance they can drill due to the weight of the pipe.
The carbon fibre-epoxy resin drill pipe is likely to weigh less than half the weight of steel drill pipe. More pipe can be stored on floating platforms and drilling depths can be increased. The larger-diameter composite drill pipe is scheduled for its first field tests in April 2003.
Using older wells as entry points reduces the environmental footprint of drilling and production operations. The 2 ½ inch diameter drill pipe may lead to the design of larger pipes for deep-water applications. Researchers may also be able to embed an electrical wire in the resin to provide a high-speed data link for transmitting electronic information to and from the drill bit.
The carbon fibre drill pipe could offer another major advantage. It would be ideal for embedding an electrical wire inside the resin to provide a high-speed data link for transmitting electronic information to and from the drill bit.
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