Carbon-fiber resins key new technology.

Composite pipe could bring new life to thousands of idle wells.
The Department of Energy (DOE) earlier this summer announced the development of a new composite drill pipe that is lighter, stronger and more flexible than steel, which could significantly alter the ability to drain substantially more oil and gas from rock than traditional vertical wells.

“This is another example of the technology breakthroughs in the arena of domestic energy production being carried out by our Office of Fossil Energy,” says 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 - made from carbon fiber resins - 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 fiber 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. It is more expensive than traditional steel pipe, but can cycle or rotate through a short radius bend for extended periods of time without suffering fatigue damage. Plus, it can be reused in multiple wells leading to a significant decrease in drilling costs.

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. Using older wells as entry points reduces the environmental footprint of drilling and production operations. The 21⁄2-inch-diameter drill pipe may lead to the design of larger pipes for deep-water applications. Researchers also may 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 Energy Department's National Energy Technology Laboratory previously announced that the drill pipe, made from carbon fiber resins by Advanced Composite Products and Technology Inc., (ACPT) of Huntington Beach, Calif., performed flawlessly in a short radius horizontal drilling field test in Tulsa County, Okla. As a result, the company that conducted the test, Grand Resources Inc., of Tulsa, is using the pipe in a second well and has plans for using it in as many as 14 additional wells in the area.

The new drill pipe - the latest product of the Energy Department's oil and gas research program - could be a major boon to energy producers in the United States. 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-foot 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. Fewer pipe failures occur, less pipe is needed because of the shortened radius, and the drill pipe can be reused in multiple wells. That combination can lead to a significant decrease in 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.

In the Oklahoma test, Grand Resources re-entered an existing vertical well that had stopped producing in 1923. Just below 1,200 feet, drillers kicked off a new borehole using

21⁄2-inch (outside diameter) composite pipe that curved in a 70-foot radius until it became horizontal. Then the well was drilled another 1,000 feet. The horizontal well struck an oil-bearing zone, and Grand Resources expects the renewed well to produce 30 barrels to 50 barrels of oil per day for well into the future.

The 21⁄2-inch diameter drill pipe could be the precursor to a larger 5 1⁄2-inch diameter pipe specially designed for deep-water applications. In deep drilling, the weight of the drill pipe is an especially important factor. The lighter the drill pipe, the less torque and drag are 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 fiber-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 underwent its first field tests last year. The carbon fiber 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.