ENGINEERING, CONSTRUCTION, & INSTALLATION
Cutting system
aims to increase
safety, efficiency
As mandated by the federal government, so-called idle iron – wells, platforms, and pipelines that are no longer producing or serving exploration or support functions related to the com- pany’s lease – are being removed from the Gulf of Mexico. Since October 2010 when the Bureau of Safety and Environmental Enforcement’s (BSEE) Notice to Lessees mandate was
issued, the removal of non-producing or damaged platforms (
estimated to be as many as 650 at that time) has become an urgent
matter for offshore operators. According to BSEE, not only do these
damaged platforms pose a threat to the environment due to potential
collapse under hurricane conditions, but they are also considered
hindrances to navigation and to the safety of workers who are tasked
with the repair or the removal of these structures.
Topside removal can be accomplished by welder’s torches and derrick barges. However, the jackets or caissons upon which they stand
present a more complex set of issues. These structures require the
use of pile jetting along with mechanical or abrasive cutting devices
or explosive charges, as they must be severed a minimum of 15 ft ( 4. 6
m) below the mudline. In some cases, when internal cutting is not an
option, operators must excavate below the mudline and send down
divers with external cutting devices to perform the task. All of these
processes present technical and operational challenges and involve
considerable offshore exposure of personnel and marine assets. Versabar and Chevron teamed up with the intent of producing a safer,
more efficient, and environmentally-friendly method of severing sub-sea structures. Their goal was to find a way to cleanly sever jackets
and conductors 15 ft ( 5 m) below the mudline with a minimum of
direct personnel exposure and at the same time remove the accompanying structures following completion of the cutting operation. An
additional consideration was to accomplish these objectives without
the damage to the marine environment caused by explosives.
While Versabar committed to engineer a working prototype, Chevron provided a 250-ton caisson-mounted topsides 3 mi ( 5 km) offshore
near the Texas-Louisiana border to test the prototype.
Versabar President Jon Khachaturian said the challenge of the project
was twofold. First, the company had to develop a cutting wire powerful
enough to cut through piles and conductors with internally grouted casing strings. Second, it had to design a delivery system for the cutting wire.
Over a two-year period including months of testing at the company’s
Belle Chasse and Houston facilities, Khachaturian and his engineering
team determined that the optimum cutting solution was a standard 2½
wire rope threaded with custom-engineered tungsten-carbide beads 6
in. long and 4½ in. in diameter.
Meanwhile, the company’s engineers addressed the delivery system for the cutting wire. They needed to develop a structure strong
enough to support the wire during the cutting process while affording
Peter Devine
Versabar
Operated by hydraulic winches, the wire sawed through a pipe 24 in. in diameter with a 2-in. steel
wall in less than one hour. (All photos courtesy Versabar)
The cutting wire sawed through the mud and cleanly severed the 60-in.
caisson along with both internal and external conductors.
New prototype device advances
decommissioning technology
