An operator in the Mobile Bay, Gulf of Mexico (GOM), needed to mill through calcium carbonate and an unknown obstruction under extreme conditions below 22,000 ft with temperatures exceeding 400 degF and an inclination of more than 30°. This is the first time the operator attempted to clean out an HPHT well in the area. The operator previously used a high-temperature positive displacement motor (PDM), impact tool, and jet assembly, but none of them was able to deliver satisfactory results.
SLB recommended using the 2 1/8-in Neyrfor TTT thru-tubing turbodrill to clean out the scale while performing an acidizing job in the HPHT well. The turbodrill has an all-metallic construction that can withstand temperatures up to 572 degF and be used with exotic fluids and acids. In addition, the turbodrill's high speed produces small cuttings that are easy to get out of hole. Its highly reliable turbine system enables it to facilitate multiple runs.
The Neyrfor TTT turbodrill milled approximately 137 ft at 2 ft/min to expose perforations. In a total of 59 operating hours, including the acidizing job, the turbodrill was pulled out of hole in excellent condition.
