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Abstract Traditional method of casing cutting takes long time as it requires two trips and there are risks associated due to long section of 9-5/8" casing that need to be retrieved. Furthermore, cutting casing in compression is not ideal in our case. Using cut and pull motorized system has an advantage in which surface verification for successful cut downhole can be observed on rig floor however one of the main challenges is to utilize a low specification mud motor 4-3/4" with flow rate range 150 - 250 gallon per minute (GPM) that can deliver approximately 4.45 K ft-lbs torque at 860 psi pressure differential across the tool. The one trip system consists of standard spear with spear stop sub, a spacer to accommodate the cutting depth, 8-1/4" hydraulic casing cutter with carbide inserts and 4-3/4" mud motor. The spear in the string helps to keep the casing in tension meanwhile the mud motor will deliver torque for the casing cutter knives to complete the job. The single trip cut and pull system was performed successfully to cut long sections of 9-5/8" in 20 minutes only and managed to pull the 9-5/8" casing out of hole to surface without additional trips required. Monitoring string hook load and standpipe pressure are critical throughout the operation. All tools were functioned as expected although the cutting time take much longer compared to the bigger mud motor with higher specification in order to deliver maximum torque for the casing cutter. Knives came out of the hole in normal conditions with carbides worn-out observed at the knife tip. This successful cutting operation enables the operator in Kuwait to perform open-hole sidetrack below the 13-5/8" casing shoe, eliminating the cost to re-drill the well and reduces operational rig time. The integrated BHA design is proved to be applicable for onshore application despite the limitation of the rig.
Al-Saadi et al. (Tue,) studied this question.