Strip and bleed procedure

Application: Appropriate when stripping 30 stands or less or when gas migration is not a problem.

Procedure:

1. Strip the first stand with the choke closed to allow the casing pressure to increase. NOTE: Do not allow the casing pressure to rise above the maximum allowable surface pressure derived from the most recent leak-off test.

2. Bleed enough volume to allow the casing pressure to decrease to a safety margin of 100 200 psi above the original shut in casing pressure.

3. Continue to strip pipe with the choke closed unless the casing pressure approaches the maximum allowable surface pressure. If the casing pressure approaches the maximum allowable surface pressure, then bleed volume as the pipe is being stripped to minimize the casing pressure.

4. Once the bit is back on bottom, utilize the Driller s Method to circulate the influx out of the well.

Combined stripping/volumetric procedure

Application: Procedure to use when gas migration is a factor. Gas is allowed to expand while stripping. Mud is bled into a trip tank and then closed end displacement into a smaller stripping tank. Trip tank measures gas expansion similar to volumetric method. Pressure is stepped up as in the volumetric method.

Worksheet:

1. 1. Select a working pressure, Pw. Recommended Pw = 50 100psi.

   2. Calculate the hydrostatic pressure:

   
   

   3. Calculate influx length in the open hole:

   
   

   4. Calculate influx length after the BHA has penetrated the influx:

   
   

   5. Calculate the pressure increase due to bubble penetration,...