Cutting tool provides safe, clean cuts in downhole tubulars
19 June 2008 in Facilities (PFC)
The dangerous practice of cutting downhole tubulars now has a safer alternative, thanks to Weatherford. The oilfield technology provider's new Motorized Cutting Tool (MCT) cuts tubulars mechanically, rather than relying on traditional methods employing explosives or chemicals.
"The MCT is an electrohydraulic tool containing a cutting wheel that replaces explosives or chemicals for cutting downhole tubulars," said Jean Paul Amiel, Senior Engineer for Weatherford's Wireline Services division. "It is suitable for many applications, including tubulars under compression or wells in which multiple cuts are required in a single run."
The tool is deployed down the tubular using a standard monoconductor cable. Once lowered to the required depth, a set of anchors are hydraulically deployed from within the tool. The anchors contact the tubular wall, centralizing and locking the MCT in place against the tubing.
Once in place, a separate section of the tool that contains a rolling cutting wheel begins rotating on its axis. During rotation, the tool applies force to the cutting wheel, which plastically deforms and displaces material as it advances, rather than cutting through the wall in the traditional manner of a saw blade. The result is an extremely smooth cut with minimal debris left behind and no flaring out of the tubing at the cut.
The MCT's progress is monitored in real time from the surface using a notebook computer. The cutting process is charted graphically, showing tool voltage and current to reveal the exact time the cut was initiated and completed. An engineer will know immediately when the cutting tool has successfully completed a cut based on the readout received. The tool stops advancing once the cut is made, thus avoiding damage to surrounding tubing in those wells containing multiple completions.
In addition to providing significant safety advantages and logistical cost savings over deploying explosives or chemicals, the MCT provides substantial operational time savings as well. Because no explosives are involved, no shutdown of communications is required during the cutting operation. In addition, the MCT can be run during inclement weather events (lightning storms, etc.), requiring no operational shutdowns.
Amiel said that beyond its technology advancements, the MCT presents significant operating cost savings over traditional cutting methods. "The MCT consumes less power. There is no need to redress the tool in the field, and one cutting wheel can make as many as 10 cuts before having to be replaced." Because the pipe does not have to be under tension to cut, the MCT can make multiple cuts in a single run, thus saving rig time by eliminating the need for multiple runs to dress the top of the fish or perform a burnover.
The MCT requires a supply voltage of 130 V applied at the tool head, and typically runs on 1 A of power. The tool is rated to operate at a maximum temperature of 300° F (149° C) and a pressure of 10,000 psi. The maximum pipe wall thickness the MCT can cut is 0.25 in. (6.35 mm), and it is able to successfully complete most cuts within 6-25 min depending on the thickness and metallurgy of the tubing string.
The MCT caught the attention of the judges of the Spotlight on New Technology Awards, presented each year in conjunction with the Offshore Technology Conference (OTC) in
- New and innovative-the technology must be less than two years old and must not be in violation of any known patents.
- Proven-the technology must be proven through full-scale application or successful prototype testing.
- Broad interest-the technology must have broad appeal for the industry at large.
- Significant impact-the technology must offer substantial benefits over current technologies.
To learn more about Weatherford's MCT, visit www.weatherford.com, or contact Jean Paul Amiel at +1.713.693.4903.
Ted Moon is the Technology Editor of JPT Online. He brings information on emerging technologies, R&D successes, new field applications, updates from SPE papers about recent innovations, and more. If you have a question or suggestion for future article topics, email Ted at teched@spe.org.