Already an industry partner for 80 years in the automation of drives and controls

Stick-slip mitigation – Ztorque

Ztorque is the latest Shell-developed torsional vibration mitigation system. Ztorque is a wide-band impedance (Z) matching concept, which requires no tuning. The technology is based on transmission-line theory with an underlying ambition of absorbing all torque waves arriving at the top drive. This is in contrast to Shell’s classic Softtorque Rotary System (STRS), which is focused on absorbing torque waves of the first vibration mode and needs regular (stand by stand) tuning as the well deepens.

The main properties of Ztorque are the following:

1. Wide-band ability to absorb torsional vibration modes for most drilling conditions
2. No tuning required

The ability of the system to perform across the bandwidth is determined by the system design and hardware available on the rig. The operational performance of such a system can be analyzed using control-system analysis techniques. The key performance indicator used is called the Hummingbird Plot.

Electroproject’s unique approach to Ztorque

As part of the development team for Ztorque, Electroproject has unique insights on the functionality and background of Ztorque technology. These insights have led to a unique proposition for the implementation of the Ztorque controller:

• The Electroproject Ztorque controller is a standalone controller, which can be used on all electrical TDs.

The implementation is less intrusive than other solutions as the controller is not programmed in the VFD but on an external IPC.

• In a regular Ztorque implementation, the controller is programmed in the VFD during commissioning. There is little possibility of the implementation making an impact on existing equipment before commissioning. The Electroproject implementation is different. Electroproject Ztorque is configured and tested before implementation and, therefore, has a low-risk profile.
• Implementation at the rig is faster as the Ztorque controller has been pre-tested. In our experience, fewer issues need to be resolved at the rig, which improves the commissioning time.
• The Electroproject Ztorque assistant software predicts the behavior of the Ztorque controller in advance. The ability to show possible roadblocks or predict the influence of torque availability and drill-string configuration ensures effective mitigation performance.
• Electroproject Ztorque is not a black box. The state-of-the-art data logger delivers high-fidelity data with 200 Hz resolution. This data, together with analytic tools like Electroproject Ztorque, show, in detail, the drill-string behavior under Ztorque control being of great value researching occurred events and documenting performance.

Electroproject Ztorque’s 100% implementation success

Electroproject has already delivered tens of Ztorque systems for major brands’ TDs and VFDs, all with Shell certification; all successfully implemented.

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