DIRECTIONAL DRILLING FOR GAS LINE SETS TWO RECORDS

Successful directionally drilled crossings of three major elevated waterways in California shows that long distance, large-diameter crossings are possible even in such environmentally sensitive areas. Contractors successfully placed 42-in. product pipe under elevated waterways in the Sacramento Delta, 58 miles northeast of San Francisco, without breaching any levees or causing an underground fracture. Either event would have resulted in a major flood. This paper describes the levees, the geology, the planning and preparation for directional drilling, containment structures and work pads that were used, and operational considerations (equipment, cuttings removal, environmental measures, circulation and installation problems).