Coiled tubing

Low-Force Shear Blades Developed for High-Strength Coiled Tubing

The paper describes the iterative process of development of a novel shear blade able to cut high-strength coiled tubing with 50% of the normal shear force.

Developed CT shear blade.
Fig. 1—Developed CT shear blade.

As coiled tubing (CT) grades have evolved during the past 20 years and wall thicknesses have increased, the resulting force required to shear coil has more than doubled. An industry need existed to develop a shear blade for blowout preventers (BOPs) that could cut high-strength CT using legacy pressure-control equipment already in use. The paper describes the iterative process of development of a novel shear blade able to cut high-strength CT with 50% of the normal shear force.

Objective

The objective of the work detailed in the complete paper was to develop a novel CT-shearing system capable of cutting high-strength heavy-wall CT with reduced hydraulic pressures. Considering that CT will continue to evolve in terms of yield strength, the goal of the study was to future-proof BOPs wherever possible to protect customers from the liability of obsolete equipment.

The authors write that, ultimately, BOPs will need to cut 175-grade CT strings with a 7-mm wall thickness with 103 MPa of wellbore pressure and less than 17.2 MPa hydraulic pressure.

Development Process

Initially, the following five options were considered:

  • Larger-diameter cylinders.
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