Abstract

With the increasing demand of gas worldwide, some highly sour oil and gas reservoirs have been explored in Russia, Middle East, China and North America. The development of such fields, which contain a high percentage of sour gas, represents significant technical challenges regarding drill pipe integrity and operations safety. Sour service drill pipe have long been used with tool joints and tubes meeting separate criteria for sour service as defined by several industry standards. This solution is still acceptable today for most of the current fields. However, the new challenges associated with the particularly sour fields require new highly engineered drill string solutions in order to increase the safety margin related to Sulfide Stress Cracking (SSC) failure risks, especially in the welded zones.

Drill Pipes are commonly produced by assembling pipe and tool joins through friction welding. The weld, as a result of this process, presents, nevertheless, some challenges for preserving SSC resistance due to some metallurgical factors such as heterogeneous microstructure, different chemical compositions between the tool joint and the pipe body and high hardness values close to the welded line. Hence a new drill pipe configuration has been developed including modified chemical composition and modified manufacturing process. These modifications allow for the improvement of mechanical properties performance and SSC resistance in the welded zone.

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