The inertia gyro provides the first autonomous system to be able check and verify a bore’s exact position both during drilling and after pipeline installation. This new survey system also allows for existing services to be accurately mapped and added to existing databases.
Earlier this year, 16 DN160 conduits were installed using horizontal directional drilling for high voltage and earth cables under the Longford Gas Plant located in Sale, Victoria. The conduits were installed uncased, grouped in four bundles of four in a trefoil configuration at a drilled length of just over 1 km. The minimum spacing distance between the parallel bores for the high voltage cables was critical to maintain adequate cable ratings, as the current ratings are influenced by mutual heating from adjacent conduit groups.
Stockton conducted gyro surveys of each installed bundle, providing an independent third party verification and confirmation of the exact position of each conduit, and therefore separation distance.
Stockton was also engaged by joint venture partners McConnell Dowell and Consolidated Contracting Company to conduct an end-to-end survey of their fluid filled 168 mm drill pipe. Adjacent to the crossing was a large piled cofferdam and numerous screwed piles used for the causeway and bridges for the Narrows construction located in Queensland. These structures had caused magnetic interference issues and positional uncertainty during drilling.
By conducting an independent gyro survey the pipeline owner can mitigate potential future risk by confirming the exact position and bend radius of the installed pipe. The gyro was run several times from end-to-end using Stockton’s variable speed and torque electrical winches. The data was immediately processed onsite and the bend radius and positional data transferred directly to the drilling superintendent, thereby minimising any operational downtime. The survey provided the required confirmation of bend radius and position of the duct, allowing for crucial decisions to be made about the bore
For more information visit www.stocktondrillingservices.com
