MechLOK™, Getting Technical with David Charles

What is a drill pipe swivel?

Drill pipe swivels are used to run lower completions or liners to target depth, typically on high angle, horizontal, ERD and complex wells. They are run to maximise the available string weight without transmitting rotation to the completion or liner below. They also mitigate helical buckling in the deployment work string.

The MechLOK™ Drill Pipe Swivel is designed to be locked using a fully mechanical process. Should a primary hydraulic release mechanism fail, the drill pipe swivel is locked to enable contingency mechanical release of the liner hanger running tool usually by rotating to the left.

Benefits of running a drill pipe swivel

The ability to rotate the work string without rotating the completion or liner is the primary benefit of the drill pipe swivel. Rotation of the running string allows for:

  • Reduction in frictional forces such as touch points and sideloads which can increase drag whilst running in hole. The rotation of the running string increases the available string weight to push the lower completion or liner to target depth.
  • An increase in the set down weight that can be applied before sinusoidal or helical buckling occurs. Severe helical buckling can prevent movement by locking up the running string.
  • A reduction in rig time by optimising pipe management, in terms of picking up and laying down HWDP or drill collars for running completions.

Development of Deep Casing Tools MechLOK™ Drill Pipe Swivel

Deep Casing Tools first developed the MechLOK™ Drill Pipe Swivel in October 2018. They recognised a need in the industry for a solution that didn’t impact the use of hydraulic equipment. Since then, it has helped major operators around the globe reach target depth with completions and liners.

We are proud to say that our intelligent technology in the MechLOK™ Drill Pipe Swivel is a world’s first. The first drill pipe swivel to mechanically lock, it can be locked at any time during operation without impacting any associated hydraulic mechanisms. This allows for the deployment of the work string to be rotated independently of the completion resulting in reduced drag, redistributed friction and mitigation of helical buckling, increasing the available weight to push the completion or liner to TD.

How does the MechLOK™ work?

After designing and building the first prototypes, they underwent comprehensive endurance testing, passing all at the end of October 2018. Its heavy-duty bearings were tested to 125,000 lbs compression forces at 50 revs per minute for over 12 hours. They were also pressure tested to 10,000 psi in both swivel and locked mode.

Following successful endurance and qualification tests the MechLOK™ was ready for field trials. There are currently two sizes of the MechLOK™ available, the MLK550 for 5” to 5.5” drill pipe and the MLK350 for 3.5” to 4.5” drill pipe. The MLK550 field trial took place in New Zealand and the MLK350 in the United Arab Emirates.  

Here at Deep Casing Tools, we use DrillScan’s industry leading drilling engineering software WellScan, to provide pre-modelling for every MechLOK™ run. WellScan has intelligent built-in features that are designed specifically for modelling torque and drag and buckling with drill pipe swivels. WellScan has industry leading 3D modelling algorithms allowing for enhanced visualisation of forces, providing robust analysis using new numerical methodology, an essential for today’s complex wells.

Once modelling has been finalised and approved by both the team and client, the MechLOK™ is then shipped to be placed within the running string above the packer/hanger. This placement assures that the maximum string weight may be applied to ensure the completion or liner is set at the required measured depth.

The tool works by rotating either right or left when in compression, and when a lower and upper sub are stroked in. It is locked by pulling the string into tension, stroking apart the upper and lower subs and rotating the string to the right. Exactly 25 right hand turns will lock a MLK550, and 40 right hand turns will lock a MLK350.

The MechLOK™ MLK550 has an ID of 2.60 inches and the MLK350 has an ID of 1.83 inches allowing for all sizes of activation balls to pass through including contingency sizes. The internal drift will never be blocked by tool operations.

Since its design and development in 2018, the MechLOK™ tool has successfully helped many projects for major operators across the globe. A sought-after tool within the energy sector, the MechLOK™ continues to deliver time savings, cost efficiencies and of course, a reduction in emissions.

Benefits of the MechLOK™ tool

The main benefit of the MechLOK™ tool is that it can be locked at any time, removing hydraulic concerns. It can be locked so that the entire string can be rotated to perhaps orient elliptical shoe but thereafter still provide a full-bore pass through for an activation ball.

It's locking mechanism has the advantage of being pressure insensitive. Washing down with rotation of the running string, and sudden pressure spikes will not cause the tool to accidentally lock. This reduces the risk of potentially transmitting torque to the lower completion.

The MechLOK™ also has the advantage of being easily reset in a matter of minutes on the rig floor or pipe deck. This allows for multi-well use on a project.

The MechLOK™ is designed to be a practical, simple, and reliable solution for running lower completions and liners anywhere in the world. If you would like more information about our MechLOK™ technology or want to talk to the team about how it can benefit your well operations now and, in the future, get in touch with Dave Charles on david.c@deepcasingtools.com or +44 (0) 7572 858573.