Carbon fibre drill pipe performs perfectly
10 Jan 2003
A new lightweight, flexible drill pipe engineered from composites rather than steel has passed an important field test in a US Department of Energy project and is now being readied for commercial use.
The US Energy Department's National Energy Technology Laboratory announced that the drill pipe, made from carbon fibre resins by Advanced Composite Products and Technology (ACPT) of Huntington Beach, CA, performed flawlessly in a 'short radius' horizontal drilling field test in Tulsa County, OK.
As a result, the company that conducted the test, Grand Resources 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 US. 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 the 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. The 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 1200 feet, drillers kicked off a new borehole using 2½-inch (outside diameter) composite pipe that curved in a 70-foot radius until it became horizontal. Then the well was drilled another 1000 feet. The horizontal well struck an oil-bearing zone, and Grand Resources expects the renewed well to produce 30 to 50 barrels of oil per day for well into the future.
The 2½-inch diameter drill pipe could be the precursor to a larger 5½-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 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.
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.
Development of the composite drill pipe is being funded through a $3.6 million contract from the Energy Department's Office of Fossil Energy. ACPT is providing nearly $800,000 in cost-sharing and more than $600,000 in equipment.
