Gain control of a lost circulation zone

While trying to gain control of a lost circulation zone in an exploration well, Villahermosa, Mexico, the drillstring became stuck after a trip to surface. During the initial trip out, the BHA was pulled back to surface without incident. However, during the trip back in, a tight spot was found at 1,891 m and at 1,935 m, and the BHA became stuck. Circulation, rotation, and vertical movement were all lost.

Recover a stuck drillstring

The Hydra-Jar AP double-acting hydraulic drilling jar was selected to run in the drilling assembly, enabling recovery operations to begin immediately. During the prejob stages, modeling was performed to determine the optimal placement of the jar within the BHA. For this operation, packoff was the biggest risk for stuck pipe mechanism. Therefore, the jar placement had to be maximized for impact forces. The model calculated the maximum impact force with six drill collars below the jar and three drill collars with 15 heavyweight drillpipe above the jar.

Avoided fishing operation, saving USD 430,000

Once the BHA became stuck and circulation could not be established, the jarring operation began. During the operation, Hydra-Jar AP drilling jar fired 568 times at an impact force of 304 tons. The operation continued for 16.5 h without stopping, maintaining good performance throughout the firing operation. As a result, circulation was re-established and the drillstring was freed. The jar's detent system provided consistent loading and firing over a broad range of hole conditions, and its metering process helped sustain the jar's hitting force even after repeated firing.

After 16.5 hours of firing without issues, the drillstring was freed, and circulation was restored. The drilling jar showed normal wear, and the successful retrieval of the drillstring saved the operator USD 430,000 by avoiding a fishing operation.