Please watch the footage below. It was a flow back after breaking out the lubricator on the rig floor.
We don’t know full details what was happened but from what we’ve seen in this VDO, it shown that the well was flowing after the wireline operation was completed. The crew broke out the connection between the wireline lubricator and the string set on the rotary table. Few seconds after the connection was removed, the well flowed back. The flow became stronger as you can see the drilling fluid was pushed out from the drillstring quickly and the rotary table started to turn black. The lubricator was pushed by hydraulic power from the mud and it was swung around. Eventually, the crew went back to connect the lubricator to the string and the well stopped flowing. It seem like the situation was under control at the end. Luckily, there was no gas or any spark that can cause fire on the rig floor.
What Could be Done Better?
These are some key learning points that we can learn from this VDO.
- A Full Opening Safety Valve (FOSV) should be installed on top of the string. If the well is flowing, the crew shut the well in by closing the FOSV. The risks to the crew will be greatly reduced.
- Under estimation of formation pressure and wellbore hydrostatic pressure. Pore pressure greater than hydrostatic pressure will create an underbalanced condition.
- Contingency well control plan should be in place prior to performing the operation. This VDO shown that there was no plan to handle the unexpected well control situation. Typically, if this case is happened, the crew should be ready to stab the FOSV so as to shut the well in.
- Ensure the connection of FOSV is the same connection as the tubular otherwise a cross over must be prepared.
What Are Your Thought about This Case?
We would like to hear from your experience so please feel free to share your thought with us.
They should check/bleed off connection to know real condition in string
Hi,
regarding the video on the link below, please have my comments:
https://www.drillingformulas.com/well-flowing-after-disconnecting-the-wireline-lubricator-well-control-situation/
As I see the order of equipment (from top to bottom) is as follows: Wireline Lubricator > Wireline BOP > Circulating head (with valves on it and hose from side). It looks strange for me to have quick union connection on circulating head to the string??? OK, lets put it aside, it is very important to know the operation type to judge or point on mistakes. Scenario A: If it was live well and there is X-Tree below rotary table than the best way is to close top swab valve, and there is not need for FOSV. Scenario B: If there is BOP closed on the string then guys made many mistakes. These mistakes are: 1. Didn’t performed proper flow check. 1. Probably didn’t accounted line displacement and were not filling well during pulling out. 3. Started to R/D equipment in a wrong order (probably to gain time). Also, I think FOSV is not mandatory for this case, because proper circulating head can be interchangeable.
Regards,
Giorgi
In addition to my prior comment a 10 minute flow check/monitor well should be done to ensure drilling fluid is of sufficient density. Not sure if this step was taken.