A new acquisition by The Expro Group promises benefits in many areas of downhole production operations.

Recently, The Expro Group announced the acquisition of the downhole tractoring business of SmartTract. The acquisition is part of an overall strategy to develop cost-effective rigless intervention systems for worldwide applications.

According to the company, the versatile SmarTract tool can be deployed in casing or tubing, conveyed by electrical wireline, to provide bi-directional force that can be used to convey all kinds of logging and completion tools, not only in horizontal wells, but in wells whose trajectory actually bends upwards past 90°.

The SmarTract tool has been deployed around the world and is known for its reliability, and its reputation for being able to operate in some highly challenging well bores that have pushed the limits where tractors can operate. Its motion is provided by setting an anchor against the wall of the well bore, then powering the tool forwards (or backwards) through the anchor. The anchors alternately grip and release the wellbore wall as the tool body shuttles back and forth, propelling the tractor in either direction in an inch-worm-like motion. The vehicle is powered by an electro-hydraulic pump and can be run on standard multi or mono conductor electric line. While downhole the tractor can be programmed and controlled in real-time via a laptop computer. Required speed, anchor arm and pulling force as well as direction can all be controlled from surface, thus optimizing the overall job for the operator. SmarTract uses a sophisticated software modeling program, called Cerberus, for prejob planning that supports and enhances tractor operations as well as predicting and optimizing the use of tractor force.

The list of possible applications is impressive:

• Production logging
• Perforating
• Packer-plug setting
• Cement bond logging
• Pipe recovery - chemical and jet cutting
• Fishing - back off
• Downhole camera
• Borehole seismic
• Magnetic ranging
• Mechanical applications - sleeve shifting, gas lift mandrels

The company announced they have just been awarded a 3-year contract by EnCana starting in June 2004. Primarily, services will include the conveyance of a magnetic ranging device used to enable precise directional drilling of the second horizontal well of each pair in the steam-assist gravity drainage (SAGD) project. The magnetic ranging device is critical in enabling the driller to steer the upper well trajectory, maintaining a uniform distance from the lower branch for its entire length. In addition, cement bond logs and casing inspection tools will be conveyed by the tractor.

Tractors prove their mettle

In several recent applications, the SmarTract system has proven to be efficient and very cost-effective. One Canadian operator used the system to convey logging tools on a horizontal section. Compared to coiled tubing (CT) which was used previously, the tractor was rigged up, in and out of the hole and rigged down in 12 hours, while the CT unit was still rigging up. And as an added bonus, fewer personnel were required.

In the Gulf of Mexico, a 260-lb tractor saved the operator from hiring a 50,000-lb crane to deploy a wireline/CT unit for intervention work. According to the company, the operator saved more than US $500,000 in costs while reducing risk by using fewer personnel.

Another Gulf of Mexico workover had originally planned to use CT from a lift boat with a projected operational total CT time of 5 to 6 days. The tractor performed the complete intervention in 30 hours, with in-well time of only 5 hours, and fewer personnel onsite. Meanwhile, compared to drill pipe conveyance, the tractor again proved its worth on a Gulf of Mexico jackup rig. Normally requiring 25 hours of rig time when conveyed by drill pipe, a cement bond log was run in 7 hours by tractor saving the operator approximately $100,000.

The versatility of bi-directional force was effectively demonstrated when a tractor was used to convey a nuclear logging string to bottom in a lateral well. During logging, the logging tool became stuck and the wireline company was unable to free it after applying 3,000 lb of line pull against a 3,500-lb-rated weak point. The tractor was energized and put in reverse. It was able to apply 850 lbs of pulling force below the cable head to give a combined pull of 3,850 lb which safely freed the tool string within a few minutes, saving the operator 7 to 10 days of fishing time.

The bi-directional capability of the SmarTract tractor is commonly preferred by operators over uni-directional tractor systems because of this risk reducing ability. Operators like to know that they can apply up to 1000 lb of upward force from below the cable head if unexpected problems such as this ever arise.

An aid to production optimization

Perhaps the most interesting application of the SmarTract tractor is in completion work in highly-deviated or horizontal wells or laterals. The tool can be deployed in producing wells to open and close downhole sleeves, set and retrieve plugs and packers, and set or retrieve gas lift valves. When equipped with custom designed jars, the tractor can apply 800-lb of force to trigger 9,000 lb of upward or downward jarring force. The SmarTract tractor offers the operator a flexible and optimized operation by being able to control the tractor and jarring direction and the amount of jarring from surface via laptop during the job.
In gas lift applications, the tractor can orient kickover tools for deploying gas lift valves or dummy valves in side-pocket mandrels without relying on cable tension.

Used in conjunction with downhole monitoring devices that keep operators informed of production dynamics, a versatile tractor can perform all the functions normally performed by costly intelligent well equipment such as variable downhole chokes. The company argues that only a small minority of wells need 24/7 adjustment. Several wells, even an entire field, can be serviced by a single tractor and kept at optimum productivity status, without unacceptable delays.

Operators have suggested new applications for this design of tractor to be used in their wells and The Expro Group intends to expand the role of the device to meet this growing interest.

Small, but powerful

The SmarTract tractor is only 21/8-in. OD, but can operate in the full range of tubulars from 27/8-in. to 95/8-in. (For the SAGD project, the tractor's upper limit has been increased to 113/4-in.). Small as it is, it can apply 1,000-lb of pulling or pushing force, and can move at up to 1,800-fph, the same speed as standard nuclear logging tools. The tool is rated at 15,000 psi and 300?F (150?C). Rig up takes less than 15 minutes, and operation is robotic as controlled by a surface computer. A real-time load cell in the cable head keeps the operator continuously apprised of the tool activity relative to its function.

The addition of the SmarTract product line to the products and services offered by The Expro Group enhances the company's ability to reliably perform critical operations cost-effectively in high-angle wells.

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