The first and most important part of the well servicing cycle is of course understanding the "job type". Conducting the necessary troubleshooting steps, and diagnosing the problem will allow you to determine what job type you are confronted with. On my website, I have a detailed step by step procedure on troubleshooting rod pumping wells. Depending on what type of wells are in your field, it would be useful to provide operators with detailed troubleshooting procedures for each. This will ensure you get the information you require to properly diagnose the failure and determine best course of repair. Depending on what is wrong, you can approach the intervention differently (service rig vs flushby, etc.)
For the purpose of this series, I will focus on rod pumping wells, in order to dig into some details. Depending on what type of wells you have in your field, everything can be modified accordingly.
Troubleshooting
There are many pieces of information that go into troubleshooting a well. The first, and easiest things you want to check are the tubing and casing pressures. Any fluctuations from normal operating conditions can flag a problem. For example, a hole in the tubing can cause the tubing and/or casing pressures to drop lower than line pressure and maybe even go on a vacuum.
Next you can check the pump action by monitoring the tubing pressure while the flow line is shut in or by looking at the pump card if the well has a pump off controller. If you are not getting a good fluid load, it could be a few different things. Some possibilities are rod part, pump failure, or pump starvation. This could mean that the formation is not delivering enough fluid to keep up to the pump. Shooting a fluid level will tell you if the pump has fluid available at the pump intake.
The last step you can take at the wellhead, is to bring in a pressure truck and pressure test the tubing. I always like to displace at least a full tubing volume to ensure you definitely have a leak. I have experienced times where the tubing was nearly empty due to fluid draining out (through the pump or a tubing leak) or the well kicked and swept all the fluid out to surface. The other benefit of pumping more fluid is that you might get lucky and wash foreign material out from a valve seat.
Pumping more fluid can also help you decide whether you have a failed bottomhole pump or tubing leak as well. Typically a tubing leak will open up and the feed rate will increase as you pump, where a pump failure will remain consistent.
Determining Cause of Failure
With the data obtained from troubleshooting, you should be able to decide with some confidence whether you have a tubing leak, rod part, pump failure, etc (not an exact science, but with experience you get better at it all the time.) This is important because as I mentioned earlier, you can approach each job specific to its individual needs.
If you only need to repair a rod part or bottomhole pump it is much more economical to bring in a flushby rig, rather than a service rig. Both the hourly rate and mobilization time are less. There are times that you would still use a service rig, but that typically would be something you decide after doing a thorough well review. If you decide there's reason to suspect poor tubing or a stuck pump, you might want to do a proactive tubing inspection, or have the insurance of having the service rig there in case you can't unseat the pump.
Well Review
Once you have properly established the cause of failure, you will need to spend some time reviewing the history of the well. I will get into detail on well reviews in my next entry in the series.
If you have any questions, or would like to discuss troubleshooting or cause of failures further, please contact me at (403)391-3758.
Cheers, Kalcy
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