DRILL STRING FAILURE ANALYSIS AND PREVENTIONS IN THE EXPLORATORY BLOCK OF FU COUNTY, NORTH SHAANXI

exploratory block located at Fu County of North Shaanxi has been put into exploration by Zhongyuan Oilfield since 1999, and mainly focused on the Paleozoic formation.Three wells of well Fugu-1, Fugu-2 and Fugu-3 has been drilled in succession.During the drilling operations of these wells, ROP was reduced sharply due to the drill string failures such as leakage and breakage.Classification and statistics were conducted on drill string failure in the exploratory block, and the reasons were analyzed, with some prevention measures presented accordingly.