It is not simple to identify well ballooning because the well acts almost like well control situation (taking kick). Therefore, this topic describe how to identify well ballooning and important rules when you face with well ballooning situation.
These following guidelines will help you identify ballooning.
• Drilling mud losses – you must have mud loss into formation in order to have mud flow back when pumps off.
• Flow back when pump off and flow rate decrease over time – you must line the well up into a trip tank and monitor well. Tracking volume flow back every minutes help you understand if flow back trend decreases. The key thing is “flow back rate must reduce over time”. If not, you will have well control situation instead. Monitoring well takes time and personnel must be patient.
• The more mud you lose, the faster flow back is and the longer time will take before the well is static (flow completely stop).
• Mud flow back from formations can bring gas or reservoir water with the mud therefore you may see gas peak or mud contaminated with formation water at the same depth while circulating bottom up.
There are important rules that you should know about well ballooning as listed below.
• Treat the well as kick until you are 100% sure that the ballooning occurs.
• Mud loss into formations must be happened first before you can have flow back. If you have flow back but you don’t lose any mud, this is not ballooning.
• In a ballooning well, flow back rate will decrease over time but in a well control well, flow back rate will increase over time.
Reference book: Well Control Books