These following guidelines help you free stuck drill string caused by differential sticking.
The first action that you should do to free the stuck pipe caused by differential sticking.
- Apply maximum flow rate as much as you can. High flow rate hopefully can wash the contact area so the effect of differential stuck is reduced.
- Apply maximum allowable torque in the drill string and work down torque to the stuck depth. Torque in the string will improve chances of freeing the pipe.
- Slack off weight of string to maximum sit down weight.
- Jar down with maximum trip load. Torque may be applied by jarring down with caution. The chance of freeing the pipe by jarring down is more than jarring up. Please be patient when a hydraulic jar trips because it may take around 5 minutes each circle.
The secondary action to free the pipe that you may try
- Reduce hydrostatic pressure by pumping low weight mud/pill. You must ensure that overall hydrostatic pressure is still able to control reservoir fluid to accidentally come into the wellbore.
- Continue jarring down with maximum trip load and apply torque into drill string.
- It may take a long time to free the pipe; therefore, personnel must be patient.
What should you do after the string becomes free?
- Circulate at maximum allowable flow rate. Flow rate must be more than cutting slip velocity in order to transport cuttings effectively.
- Reciprocate and work pipe while cleaning the hole. Ensure that you can work pipe with full stand or joint while circulating.
- Condition mud prior to drilling ahead because if you still drill with poor mud properties, the differential sticking will be re-occurred.
Drilling formulas Stuck Pipe Prevention Book => 
Stuck Pipe Prevention Book
