I have seen a lot of variance in performance for rig up/rig down times as well as running efficiency when using top drive casing running systems. Why are these times so different when the same equipment and number of personnel are used?
There are many aspects to this and I will try to address them as best I can, taking the rig up/rig down question first.
I would start by looking at the differences between the rigs, each rig floor comes with its own challenges in terms of how it interfaces with the casing equipment. Not all rigs are made equal and often small details related to the rigs design can have a major impact in this process. It may be that the mechanised equipment installed on the rig makes rig up more difficult, it could be that the distance between the top drive rails means that a larger more awkward bracket must be installed or that red zone policies dictate where the equipment can be placed
To streamline this operation the rig should allow as much of the rig up as possible to be conducted offline, generally this depends on the toolpusher and what access he is prepared to give. More often than not in the days leading up to the job there will be sufficient windows for the equipment to be sighted and to run the associated hoses and cables.
Hanging umbilicals offline is a good example of how to save time offline, normally this is possible when circulating at the shoe but not all rigs allow this but it’s a sure way to save 30-60 minutes. Keeping umbilicals hanging in the derrick between jobs is another sure-fire way to save time but again the rig can quite often be resistant to allowing that.
The experience of the crews and the number of times they have rigged up the equipment before has massive impact on time. Nowadays the TRS crew are discouraged from being involved in moving equipment so for them having a proactive and experienced rig crew who have experience rigging up their equipment is key. It’s also important that the deck crew and crane operator are engaged and understand what is required of them in terms of getting the equipment to the rig floor in the correct order and in a timely manner.
If the same crews are performing the task on a consistent basis then the times for rigging up and down are sure to improve. Ensure that the job is planned well in advance and have a post job de-brief to capture the lessons learned, it's important that these lessons are shared with any crews coming onboard for the first time.
Generally when running these tools the speed at which the pipe is being run is determined by the skill of the driller and the speed at which the joints are brought to the floor. This is probably the number one reason that some rigs operate more efficiently than others.
Often the driller can become distracted by things like people in the doghouse asking him questions, calling him on the phone or even if it’s he who’s responsible for the pipe tally. All these seemingly minor things can have a large bearing on the efficiency of the run. A skilled driller will be able to increase his spin in speed and reduce this for the final make-up torque of the connection, provided he stays within the pipe manufacturers make up procedure. Most rigs nowadays make this easy by having a stall out spin torque and a pre-programmed final make up torque.
There are of course other factors such as the condition of the pipe itself, poor milling for example on either the box and pin ends of the pipe can have a significant contribution to the efficiency of the job. Rig alignment is another factor that would fall into this category.
Hole conditions often mean that the running in speed has to be reduced to avoid surging the hole, often these small details are overlooked at the service quality meetings where the focus is on how many joints were run per hour, the fact that the crew was told to slow down is often overlooked!
Nowadays more rigs are able to make up offline and run in with doubles or stands, this makes the jobs shorter and there is generally less NPT since the exposure time is lessened. This method should be utilised to improve run rates where possible.
In summary, there are a variety of reasons why there isn’t consistency between different types of rigs, a combination of human and technical considerations are in play. Improved performance is often incremental and based on repetition of the jobs utilizing the same crews. Batch drilling generally provides evidence for this, the gains made on jobs performed one after the other are often quite dramatic as crews become more familiar with a specific job.