The pipe shall immediately be pulled to the maximum safe pull specified for the assembly and jarring shall commence.
If pulling and jarring are not immediately successful, the pipe shall be slugged and right-hand torque applied in an attempt to free the pipe.
Note: The pipe shall continue to be worked and circulation continued while preparing the pipe free pill.
A pipe free pill shall be spotted at the stuck point as soon as possible after initial attempts to mechanically free the pipe have failed.
Reducing Hydrostatic Pressure
Reducing hydrostatic pressure is the normal way of freeing differentially stuck pipe. However, it is essential that all aspects of well control are considered prior to lowering the hydrostatic head.
There are several ways of reducing the pressure on the formation (water can be used to reduce the hydrostatic head in a short time).
Whichever method is selected, it will be most effective if the drillstring is in compression as this tends to move the effect of the greatest stress at the stuck point.
Mud Weight Reduction
Using this method, the hydrostatic pressure is reduced by mud dilution.
The minimum mud weight shall be pre-determined and close attention shall be paid to all kick indicators. When diluting mud, it may be difficult to identify a slow influx of formation fluids as the active volume is being increased continuously. On no account shall the hydrostatic pressure be reduced below the maximum calculated pore pressure in the open hole section without the prior approval of the Drilling Supervisor.
On the other hand, if dilution is not possible, spotting a light weight pill may be an option.
Spotting Pipe Release Agents
Differentially stuck pipe can be freed by spotting pipe-free pills at the earliest possible opportunity. These agents attack and break down the filter cake, thereby reducing the bond between the filter cake and the pipe.
The volume of spotting fluid depends upon the size of the hole at the stuck point. If sticking has occurred around the collars, sufficient spotting fluid shall be pumped to cover the BHA plus 100 % excess to allow for some hole enlargement.
Once the pill is in place, it shall be left to soak whilst continuously working the pipe. Soaking times of at least 12 hours shall be considered.
During soaking, the pipe shall be worked, preferably by putting it in compression. Slack off about 10 000 lbs. below the weight of the pipe and apply some right-hand torque.
Note: If using 5in drillpipe, the amount of torque shall be approximately half a turn for every 1 000 ft of pipe above the suspected stuck point.