Extending the reach in horizontal, deviated wells can recover more reserves
Brian Schwanitz, Douglas Johnson, Kristine Henriques - Welltec
Drilling extended reach horizontal and deviated wells has been limited by the availability of economical intervention techniques. There is no point in drilling long, horizontal wells if they cannot be serviced afterwards. Traditional methods such as coiled tubing, snubbing, and drill pipe all encountered problems or had logistical issues when trying to access extended reach (ER) wells. These problems included helical buckling (coiled tubing) and the heavy and expensive equipment required by snubbing and drill pipe. These older, intervention methods also were time consuming to mobilize, required a lot of manpower, and, because of the size of the equipment, had multiple HSE implications.
Thus, extending the reach of intervention techniques in extended reach wells was in demand as valuable working hours and production were lost on some of these wells as a result of technological inefficiencies. When electric wireline conveyance was introduced, it represented a paradigm shift in intervention methods. It is a highly cost- and time-efficient intervention option that enables access to reserves that conventional intervention methods may not reach.
One tool on the market is a downhole tractor that can reach the end of ER horizontal or highly deviated wells without deploying drill pipe or coiled tubing conveyance methods. This wireline-deployed, self-propelled robotic device can push or pull wireline tool strings out to the end of the wellbore. In this regard, any job typically that is run on electric wireline in a vertical well can be done in a horizontal or deviated well with the wireline tractor.
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The wireline tractor covered a distance of 3,732 ft (1,138 m), resulting in the deepest tractor run in the Gulf of Mexico.
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The high pull force enables the tool to reach almost all ER targets, and the high speed of both the equipment deployment and conveyance to target depth keeps operational costs down. In extreme reach wells, the tool can be configured for tandem operations, which increases deployment power and performance where major ID challenges are met.
Available in two sizes (2 1⁄8 in. [5.4 cm] and 3 1⁄8 in. [8 cm] OD), the wireline tractor is optimized for pulling force and speed in conjunction with the downhole completion string. It can push large open-hole tool strings into open-hole environments (including ones with washouts), and withstand the shocks of perforating.
Track record
Any job previously done on slick-line, in vertical wells can be done with a wireline tractor in extended reach wells. These jobs include perforating, cement bond logging, production logging, running open hole logs, and enabling coiled tubing (a coiled tubing tractor has also been developed) to reach beyond the friction buckle point. Custom-made, downhole robotic solutions also are being developed on demand.
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Volume 68 Issue 9
September 2008
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