Published: 12/01/2011
Published: 12/01/2011
Upon completing a long 12 1/4-in vertical section from 957 m to TD at 3,590 m, an operator working in Oman picked up the drillstring 16 m, to perform a flow check, resulting in a stuck BHA. Circulation, rotation, and vertical movement were all lost. When attempts to jar the string free failed, Schlumberger was contacted to recover the stuck BHA.
Jar-Pact impact tool BHA placement software was used to position an 8-in Hydra Jar AP double-acting hydraulic drilling jar and an 8-in Accelerator AP impact tool in a screw-in fishing assembly, to optimize the impact and impulse values at the stuck point.
The drillstring was backed off one drill collar above the top stabilizer, at 3,536 m, and pulled out of hole. The fishing assembly was run in, the fish engaged, and down-jarring operations commenced. An 8-h period of jarring down was anticipated, followed by 8 h of jarring up.
Results were seen after only 1 h of jarring down: movement was noted and within 6 h a 14-m pocket was created, enabling circulation and rotation of the BHA. The freed BHA was pumped out of hole because of drag and excessive return of cuttings. At surface, the motor sleeve stabilizer was found to be 1/4 in under gauge and the bit was 2 1/4 in under gauge.
Recovery of the stuck BHA saved more than USD 1.3 million and eliminated the need to sidetrack. The customer requested the Hydra-Jar AP drilling jar and Accelerator AP tool for subsequent wells.
Challenge: Free stuck 12 ¼-in BHA at 3,574 m for recovery after operator had tried other means unsuccessfully.
Solution: Use 8-in Hydra-Jar AP double-acting hydraulic drilling jar and 8-in Accelerator AP impact tool—optimally placed—aided by Jar-Pact impact tool BHA placement software.
Results: Recovered stuck BHA on first attempt, with less than half the anticipated jarring time, saving more than USD 1.3 million.
