Service company goes it alone

Jan. 1, 2003
A sure sign that a new technology is gain-ing acceptance is a healthy number of companies offering competing prod-ucts. This appears to be the case with expandable tubulars.

William Furlow

A sure sign that a new technology is gain-ing acceptance is a healthy number of companies offering competing prod-ucts. This appears to be the case with expandable tubulars. Baker Oil Tools recently announced its first major success in this area, setting expandable packers, liner hangers, solid tubulars, and sand screens in three off-shore wells for China National Offshore Oil Co.

Not only does this project highlight the full range of BOT's offerings in its expandables line, but it was accomplished in one trip. This is a unique feature of the BOT system and helps to distinguish the company in a market that has growing number of players.

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Initially, BOT was to work with Shell as part of a joint venture called E2Tech. That company was dissolved over a year ago, and the two partners went their separate ways. Since then, BOT has worked to develop its own line of expandable products, using simplified materials and a piston-driven, top-down expansion process.

Intan wells

BOT successfully installed its expandable completion systems in three Cnooc wells offshore Indonesia. The three horizontal wells are Intan B-21 and Northeast Intan AC-26 and AC-25. The systems included expandable liner hangers, solid pipe, isolation packers, and sand control screens. All of the equipment was installed and expanded downhole in only one trip. The project highlights BOT's full offering in the area of expandable technology.

While Enventure, the joint venture between Halliburton and Shell, clearly enjoys first mover status in the area of solid expandables (the company recently announced the first monobore well, Offshore, October 2002), Weatherford has made its mark in expandable sand screens. Both companies have a full line of expandable products, including liner hangers, screens, and solids. For BOT to enter this market, the company needed to exploit a niche, according to Brent Emerson, director of Well Bore Construction Multilateral and Expandable Systems for BOT. The company looked at the applications of these expandables and quickly realized there was a need for a system that could readily expand into extremely deviated wells. Rather than receiving expansion energy from the drillstring, BOT reasoned it might be easier to use a system that drives the expansion mandrel from downhole, using hydraulic pressure fed into a piston and not directly from the drillstring.


BOT went on to design a system it calls catEXX. This expansion system is made up of four major components. Hanging on the drillstring, the top of the tool accommodates an anchor system. Once the system is run in the hole and reaches the touch-down point, the one-trip mechanism holds the system in place. A ball, or dart, is then circulated down, allowing hydraulic pressure to build up in the tool. The pressure activates the anchor at the top of the tool. The anchor uses a series of slips to lock the tool into place against the walls of the wellbore.

Once the anchor is activated, the pressure is transferred to a hydraulic piston below. The piston drives the expansion cone at the tip of the tool. The cone can be extended up to 20 ft, expanding the tubulars top-down. Once the piston is stroked out, the pressure is bled off and the anchor allowed to retract and move back into place behind the retracted piston.

"You just close everything back up," Emerson said.

By repeating this process, the catEXX can expand hundreds of feet of tubulars, an expandable packer, or sand screen. The fourth component in this system is the one-trip mechanism, which holds the tool in place as it is being lowered downhole and angled into the deviated section of the well. Because the system doesn't rely on push or pull energy from the drillstring, it is easily activated in deviated sections of the well. This horizontal environment is one of the key drivers behind the BOT design, said Emerson. As long as hydraulic pressure can be fed to the tool, expansion can be achieved.

Product line

Emerson said BOT currently offers its expandable sand screens, called EXPress, in two sizes, 8 1/2-in. and 6 1/8-in. The sizes are driven by market demand, and others will be added in the future. The expandable portion of the screen is a simple design using drilled pipe. Emerson said this is a robust design that holds up well to the sometimes rough trip downhole and out through the horizontal section of the well. The drilled holes might deform during expansion, Emerson said, but the key is the screen technology. This will remain undamaged. As long as production can move through the holes, they serve their purpose. The screen design varies according to the pore size of the formation.

BOT pursued applications both on- and offshore when it introduced this product line, Emerson said, but the majority of the jobs have been in deviated offshore wells. While some patents related to expandables were purchased in the development of the screens technology, Emerson said the expandable screens were designed in-house by BOT.

BOT's expandable packer, FORMpac XL works in tandem with the screens. This device acts as a traditional packer but does not affect the inside diameter (ID) of the wellbore. The FORMpac XL provides open hole isolation without cement. The packer features a metal carriage that is surrounded by an elastomer element. Both are expanded to create a barrier against the formation wall. The packer can be run with a series of sand screens to isolate discrete zones in one well. Because this packer, once expanded, does not affect the ID of the hole, it is possible to run a completion packer inside the system for more advanced production options, Emerson said.

The BOT system does not rely on exotic metals for expansion. Emerson said the company could actually expand off-the-shelf tubulars. The key is how much expansion is required. Careful selection of materials is critical when a job calls for an expansion beyond 10%, which is often the case.

"To get past 10% or 15%, we need to design the metal," he said. Most jobs will require expansions in the range of 20-25%.

The market

BOT has worked with Cnooc on a number of jobs, Emerson said. In addition to the work done overseas, he said, the company has signed a development agreement with BP to provide expandable technology to the company's worldwide asset group, including deepwater projects in the Gulf of Mexico. Emerson said BOT has a casing patch product that it is marketing and is looking at a full liner-hanger system.

Even though Enventure recently completed the first monobore well, and both Weatherford and BOT have expandable products in the ground, Emerson said he sees the industry uptake of expandable technology to be slow. He predicts the technology will continue to advance faster than the industry's willingness to adopt it. He considers the supermajors, such as BP and Shell, to be leading the effort with their use of the technology in deepwater wells, but acknowledges that state-owned companies such as Cnooc have awakend to the idea that innovative technology can vastly increase the value of their holdings.