When you trip out of hole and leave drilling mud in a static condition for a period of time, mud rheology (PV, YP and gel strength) of drilling mud tends to increase. It is very important that when you trip back in hole you should break the thick mud (most people call “break the gel”).
What can be happened if you don’t condition thick drilling mud while tripping back in hole?
Thick drilling mud tends to consume at lot of energy to move it therefore high frictional factor is occurred that will result in excessive equivalent circulating density (ECD). If formations are not strong enough to withstand the ECD, lost circulation will be happened. The lost circulation will lead to other drilling problems such as well control and well ballooning.
How can you break the gel?
The follow steps are example on how can you break gel of drilling mud.
• Trip in hole to the casing shoe depth
• Rotate pipe slowly 10-15 sec and bring pump up slowly
• Circulate bottom up at reduced speed
• Trip in hole about 1/3 – 1/2 way of open hole
• Rotate pipe slowly 10-15 sec and bring pump up slowly (staging up)
• Circulate bottom up at reduce speed and slowly reciprocate pipe
• Trip in hole to bottom
• Rotate pipe slowly 10-15 sec and bring pump up slowly (staging up)
• Circulate bottom up at reduce speed and slowly reciprocate pipe
• Drilling ahead
In the demonstrated instruction, there are many times that you stop and condition mud which will bring mud properties back to normal.
Ps, this is based on my experience you may need to adjust to suit with your drilling operation.
