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Rigonomics: Steering Tools Continue To Lead HDD Revolution
“Locating systems capable of gravity-flow installations have been around since the late 90s, and the increase in the number of gravity sewer installations using HDD can be attributed to more accurate locating systems,” said Finnsson.
Ditch Witch’s Dvorak said on-grade installations are the most recent of new applications for directional drilling.
“New and improved technology offers more precision and accuracy that is needed for on-grade drilling,” he added.
When walkover guidance systems are not practical or job conditions make their use impossible, wireline steering tools are the most widely used alternative. Wireline systems often require the use of a Tensor TruTracker grid system to eliminate or reduce the effects of magnetic interference.
Steve Cornwall, vice president of Sharewell HDD sales and services, said the most important advance for the magnetic guidance wireline steering tool has been the improvement of the software used with wireline systems.
“This has lead to the use of ‘micro-coil’ and other faster, more accurate capabilities,” Cornwall explained. "A micro-coil is a compact circle of surface wire placed in an uncongested area, like a grassy median on a busy interstate highway. This allows the operator the ability to ‘true-track’ without laying wire across the road.”
Cornwall said that probably the best example of steering accuracy for HDD is an intersect project in which two pilot bores meet and intersect.
“This type of project,” he said, “is attainable with several different types of steering systems and has expanded the ability of contractors to successfully complete jobs that previously were thought to be too difficult to achieve.”
Every locating system -- whether walkover, wireline or gyro -- has its applications and limitations. The challenge of contractors and suppliers is to match the right system to the project in order to maximize success.
Danny Crumpton, Inrock’s technical sales guidance manager, observes there has been an increase in applications where using surface coils are not possible, usually on deep water crossings where environmental concerns are an issue. New developments eliminate the need for wire grids on the surface.
“The beacon tracking system (BTS) allows engineers to reach out by 300 feet past the edge of where the coils would have to be stopped, giving greater range and tracking capabilities,” said Crumpton. “Equipment can be placed in a specific location and surrounding areas are not disturbed. It is much quicker to setup and is environmentally friendly.”