As requested by APR Drilling Tools (Wuxi) Co., Ltd., Sichuan Huafeng Drilling & Engineering Co., Ltd. conducts an on-site trial of HAU drill rod produced by APR, and hereby reports on-site drilling and using of APR drill rod as follows. Trial date: October 13, 2020 to November 2, 2020.

 

Trial place: Dachaidan Kuangou Coal Mine in Qinghai Province, ZK3-1 drilling 

Geological structure: sandstone mixed with some coal bed 

Design depth: 650m

Drilling Rig: Atlas Copco C6, maximum well drilling torque is 4000PSI

Drilling bit: HQ3 impregnated diamond bit

 

HAU drill rod of APR was used for drilling starting from October 13, 2020, the daily footage is about 35m on average smoothly and torque of the drilling machine is around 1800-2200 PSI. With normal performance, the drill rod has no water leakage, air leakage, tripping, fracture, bend and other phenomena. When drilling depth is up to 586.3m, sandstone mixed with coal bed in the well suffers large area of landslide. Well sweep started on October 24, loads in the well increase (back and forth movement) and the sweep torque is up to 3500-4000PSI. In this case, with normal performance under limited large torque, APR drill rod still has no water leakage, air leakage, tripping, fracture, bend and other abnormities. 

 

During night shift on October 30, 2020, when well sweep is up to 582.3m, torque increases, pump pressure boosts, water pipe clogs, well sweep goes up and drilling tool is stuck at 570.60m in the well. After forced pulling, forced jacking, forced operation and other methods failed, large torque is adopted for forced rotation and torque is up to 4000PSI (twice in total), lasting for 27 minutes. But the drill rod fails to be pulled out of the well and a jack has to be used. The drill rod trips at 481m in the well. According to inspection above the well, its male thread has no big problem. After replacing, the drill rod is placed down again and aligns with female thread. The drill rod is stuck again at 480.9m. After forced pulling and jacking are invalid, a hydraulic jack is directly used to pull the rod up by force instead of adopting the method of forced rotation. Under over 25MPa pressure (beyond stroke of pressure gauge pointer), the drill rod has no water leakage, gas leakage, tripping, fracture, bend and other abnormities. 

 

According to the analysis, the reason behind the tripping event is disengaged and loose thread engagement caused by long-time forced rotation under large torque and tripping is caused by forced pulling by a jack. During the second forced pulling by a jack, threaded connection of the drill rod stands over 25MPa pressure and suffers no tripping because of no forced rotation under large torque.

 

Conclusion: With reliable performance and stable quality, the batch of APR HAU drilling rods that are tried on Dachaidan Kuangou coal mine site of Huafeng can meet requirements of drilling construction up to now under such complex geological conditions.

 

 

Dachaidan Kuangou Coal Mine Project of Sichuan Huafeng Drilling & Engineering Co., Ltd.
Manager: Zhao Yong
November 2, 2020