WorldWide Drilling Resource

27 WorldWide Drilling Resource ® FEBRUARY 2019 Directional Drilling to the Rescue Adapted from Information by Layne Layne is a global water management, construction, and drilling company, providing responsible solutions for the world's toughest water, mineral, and energy challenges. Gold Slickline had previously used shaft boring machines to complete raised bores for ventilation shafts. The process had caused frustration due to deviations encountered using the method. This required them to mine over to the borehole rather than intersect the tunnel with the borehole. Meetings with Layne and IDS (Layne's Directional Drilling Division) led to Layne being hired. IDS was commissioned to directionally drill a pilot hole to intersect the tunnel, then ream the pilot hole to 14-7/8 inches. The Layne Team installed and cemented eight-inch casing throughout the borehole into the top of the tunnel, securedwith a rock-bolted plate and sealant. The directional hole was set up directly over the underground tunnel and remained vertically straight to 2000 feet, and the directional drilling stopped at 1920 feet. The intent was to install and cement casing in the borehole to facilitate material transport into the mine tunnel. The surface collar pipe was set at around 60 feet. The plan was to drill a 6-1/4-inch-diameter pilot hole conventionally to 500 feet and continue until the inclination threatened to take the path of the hole outside the desired column of a 5-foot radius. At just beyond 500 feet, the hole reached 1.3-degree deviation and was at the outer limits of the column. The directional equipment was employed. While the hole did move out of the column, it was quickly brought back into the desired zone and kept there for the remainder of the hole. In two instances, the directional drill adjustable bent housing had to be changed to combat the formation influence, but it was generally maintained at a 1.15-degree bend. This was achieved by using the performance drilling method, where the drill string is oriented to bend the hole in a desired direction, the entire assembly is slid to adjust the inclination, and the assembly is rotated when no adjustment is needed. At the end of the project, the hole managed to breakout only 30 inches from dead center of the column. This was true success for both Layne and the client. Editor’s Note: In between our print issues, the WWDR Team prepares an electronic newsletter called E-News Flash . Based on readership, this was the most popular E-News Flash article of the month. Get in on the action and subscribe today at : www.worldwidedrillingresource.com DIR