This is part two of of a two-part article. Part one is available to read here.
One of the basic requirements of any walking system is the ability to steer. After all, if steering is not needed, why not just use a skid system? Most walking systems use a mechanical system to change direction, either by rotating the entire walking foot, or, with the Kingpin Walking System, simply by turning the roller track on top of the foot.
Without automation, changing the steering direction of a walking system generally requires technicians to make manual adjustments to each walking machine. On well-designed systems, steering angles are typically marked on each walking foot mechanism, so doing a ‘crab’ move at 45° means adjusting each walking foot to steer along the 45° mark. Some systems also allow spinning the rig about well centre by coordinating the steering angles of the feet, usually by rotating each foot to a special ‘spin’ mark. To steer like a truck (with the front walking feet going diagonally and the back feet going straight), personnel need to coordinate and remember each angle to steer each foot.
Changing the steering direction of a foot is usually done by hand using a lever mechanism. Even if a power steering system is used, if it is not automated the operator still has to steer ‘to the number’.
Figure 3. Automatic steering systems allow rigs to 'spin' about whatever point the operator chooses.
With an automated system, steering can be as simple as pushing a button. With Entro Industries’ AutoSteer system, the operator can select any point on the ground to spin about, or set the vehicle steering angles to perform ‘simple’ (like a car) or ‘complimentary’ (like a firetruck) steering. The computer calculates the correct angle for each foot and makes the steering adjustments automatically. This can save a significant amount of time, since the operator does not have to go from foot to foot making adjustments, or second-guess themselves about whether negative 6° is the same as positive 354°.
The state of the art
Automatic steering keeps operators away from machinery and out of harm’s way, since steering adjustments can be made by remote control. Automatic lifting keeps the rig from being lifted unevenly, causing damage. The wireless remote with integrated machine display reduces the amount of information spotters must pass to the operator, allowing spotters to do their job more effectively.
Since the automatic walking system can react almost instantly, no time is lost going from lifting to travelling, or from lowering to resetting. Automatic steering turns a 15 minute job (with a trained crew) into a 15 second job.
The speed benefits of automation can have a compounding effect. Since automation makes using the walking system easier, crews now have another tool in the toolbox to solve problems they might have otherwise waited for a crane for, like pinning large modules together. Sometimes the most cost-effective way to move a rig to a new drill site is to simply walk it, even if it takes a few days. Moving from pad to pad along service roads is much quicker and easier with automation, since there is no downtime in the walking cycle or for steering adjustments, and those time savings add up during a long move.
Entro Industries’ AutoSteer system is designed to allow a rig to spin about any point on the ground, which can be a huge help for slant-hole rigs that have to adjust the azimuth of the rig at each well. Spinning about a point can also be useful when trying to pin align pins; an operator can set the centre point in between the pins and make minor tweaks easily. A wireless control with on-board load sensing makes getting rig weights almost instantaneous.
Even with all the automation, Entro Industries still builds walking systems as manual machines first, with automatic features as an add-on. This means the automation simply adds new features without compromising the reliability of a proven design. The aim was to make sure that the new technology would not create more headaches for the customer if a cable was damaged or there was a loss of power, for example. Even if the entire PLC is lost, it can still be walked like a manual system.
This is part two of a two-part article. Part one is available here.
Written by Nathan Klammer and Jason Ross, Entro Industries.
Read the article online at: https://www.oilfieldtechnology.com/drilling-and-production/20062019/the-next-step--part-two/
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