Composite Fiber Pipe Adds New Twist to Directional Drilling
Abstract:Early tests on lightweight, high-strength composite fiber drill pipe demonstrate the product has a place in the oil patch. Cost will determine where that place is.
Analysis:Ask Lance Armstrong—or any other distance cyclist. Composite fibers add strength, increase flexibility, and reduce weight. It is a big deal on a bicycle where reduced weight produces less fatigue and more efficiency as energy is transmitted into generating additional speed. Adding a third or half of a mile per hour makes a difference in a long-distance bicycle race.
But composite fibers could be an even bigger deal in adding to efficiencies in the oil patch. A pilot program to test the limits of Composite Fiber Drill Pipe (CDP) is in its maturation phase with practical demonstrations for small diameter pipe completed onshore. A second test using larger diameter pipe will commence in the second quarter 2003.
The composite pipe program is a three-year $3.6 million effort sponsored by the National Energy Technology Center (NETC), a branch of the U.S. Department of Energy. Los Angeles-based Advanced Composite Products and Technology Inc. (ACPT) has been the primary contractor in the pilot program.
Of course, as any cyclist can tell you, composite frame two-wheelers are a lot more expensive than their steel or titanium counterparts. As a result, only the best athletes—or those with the bigger pocketbooks—are found in the saddle.
Similarly, that cost factor will also determine the way in which the market for composite drill pipe evolves in the oil patch. As with bicycles, the initial applications will be for specialized purposes.
How composite drill pipe will impact the commodity side of the business is an open question governed by cost, manufacturing capability, and performance. There are, after all, few things as prosaic as drill pipe. It is basically rolled steel in 30-foot lengths with tool joint connections. Add a few collars for weight, maybe a downhole motor, and a drilling bit, and the magic begins.
But the drilling industry is reaching the limits of what can be done with steel drill pipe, both in terms of vertical depth and in extended reach applications.
Expanding those limits may be a key to adding new natural gas production and improving the return on investment for operators as lower drillstring weight is translated into deeper vertical and greater horizontal penetration.
The greatest potential is for use in the offshore environment. Because the weight of composite pipe is less than half that of steel, it is possible to store more pipe on offshore platforms. Composite pipe also expands rig capability. The lighter pipe means more efficient use of a rig's lifting and torque capability. Essentially the same rig capabilities can be leveraged into use in greater depths because of reduced drillstring weight. In fact, early expectations for the use of composite pipe focused on the advantages produced by weight savings. As the NETC program evolved, those expectations increased. It is theorized now that composite pipe will impact extended reach projects where the current theoretical limits are controlled by strength-to-weight ratios in the drillstring as well as friction and material fatigue. One pipe industry technical paper notes that drill pipe in 10 pounds/gallon mud reaches its theoretical vertical depth limit at 32,000 feet. Titanium can incre! ase that limit to 50,000 feet, while composite drill pipe can push beyond the 50,000-foot barrier.
In horizontal and extended reach drilling, lighter weight and greater flexibility reduce fatigue and friction and enable the contractor to push the drillstring farther. That flexibility is more than literal, however. Ultimately the pipe can be customized for specific applications, through variations in resin and fiber mixtures to meet a variety of downhole conditions involving tension and compression strength, pressure capability, and torque capacity.
Furthermore, the pipe can be used in specialized applications with standard steel pipe in which standard steel pipe would comprise the vertical sections while the composite pipe would be applied to the curved or high-angle portions of the wellbore.
Although the greatest expectations are for the offshore market, the first practical composite pipe test has been completed onshore. Tulsa-based Grand Resources, Inc. used prototype composite drill pipe for a short radius slim hole horizontal test during the fourth quarter 2002. The company re-entered an 80-year-old nonproducing well and extended the borehole 1,000 feet horizontally, tapping an oil-bearing formation. The horizontal turn was made at 1,200 feet vertical depth within a 70-foot radius and resulted in new production of 30 to 50 bbls/d.
The program may be expanded to include another 14 re-entries and illustrates how composite drill pipe can increase the industry's ability to extract hydrocarbons in a cost-effective manner, particularly in mature provinces where hydrocarbons still reside despite earlier exploitation.
Composite pipe runs three to five times the cost of standard steel drill pipe. Offsetting the expense is the fact that less pipe is needed because the radius of the wellbore is shorter. Additionally, composite pipe withstands fatigue over a greater period of time than its steel counterpart, producing fewer pipe failures. And, like its steel counterpart, it can be re-used several times—in fact, many more times than steel pipe.
Composite pipe is manufactured by winding graphite fibers and epoxy resin—hence the term "composite"—around a mandrel and the metal box and pin connections. The composite tube is cured and the mandrel is removed and used for the next section. The cured pipe is machined, then coated to resist abrasion. The same process can be employed to repair or recondition a section of used or damaged composite pipe.
Minor repairs to composite drill pipe can be made onsite in the field.
ACPT has begun a pilot manufacturing program that can produce ten 30-foot sections of composite pipe each day, or enough to create an adequate reservoir of composite pipe for commercial market tests. The pilot program involves testing composite pipe in two sizes. The initial project involved 3-3/8-inch composite pipe. The program is also developing prototype 5-5/16-inch composite pipe for the April 2003 tests.
Composite pipe offers more than lighter weight and greater strength capabilities. The pipe can also be manufactured to convey electric power or transmit signals through materials embedded in the tube walls. The current challenge is moving power or signals across the metal joints that connect the pipe, although that, too, is still on the drawing boards. With the industry on the verge of a downhole communications breakthrough that will bring realtime data transmission to remote sites as an integrated part of the drilling process, composite pipe could make a contribution far greater than simple weight reduction.
Composites work in the airline industry, as well as with fishing and bicycling materials. There is no reason they won't work in some form or fashion for the oil patch. Almost all required are a viable economic rationale—and a flexible viewpoint.