The 42 inch diameter pipeline crossings ranged from 500 to 1002 m in length and included a DN150 steel pipe for a fibre optic cable. The pilot bore was drilled with a 97/8 inch jetting assembly and utilised a Para Track 2 survey magnetic guidance system.
This process ensured an extremely high level of accuracy in the drill process, with Stockton’s rig operators frequently knocking the exit peg out of the ground. The bores were pre-reamed up to 54 inch diameter using a combination of Flycutters and Barrel reamers to combat the silty clay ground conditions.
To control buoyancy, the Stockton team inserted 500 mm diameter and 150 mm HDPE pipelines into the strings prior to pullback and filled the anulus of the pipeline with water during the pullback process.
The project set new benchmarks in Health, Safety and Environmental management for onshore pipeline construction in this developing part of Central Asia. The twin oil & gas 442 km 42 inch pipelines were also built by McConnell Dowell in Joint Venture.
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