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Moving into the next decade, wells in the Middle East are becoming more challenging as the deeper and more complex plays are exploited. This environment will be challenging from a torsional and tensile loading standpoint, and will be dynamically very active. This type of environment combined with high levels of H2S calls for a new high grade of sour service pipe. The Middle East is also opening up to the idea of high speed telemetry and wired pipe economics that call for a long lasting pipe product. When using sour service pipe that is traditionally limited to 105 KSI grades, even with an optimized string design, drillers sometimes have no other option than to sacrifice the margin of overpull, risking losing the well if fishing is unsuccessful. Alternatively, they can elect to use drill pipe, which is not suited for use in this corrosive environment, generally using API S135, with a risk of parting the string due to H2S embrittlement. To address these operational limitations, the pipe body, which is the drill pipe limiting member in tension, has to come with higher material strength and at the same time exhibit improved Sulfide Stress Cracking (SSC) resistance compared to API S135 grade. A novel grade of drill pipe was developed over a period of two years that is the strongest sour service drill pipe the industry has to offer to date and gives drillers an extra 19% of tensile capacity with its 125 KSI material yield strength. This new grade has been ordered for use in various regions of the world and for numerous applications. At this time, it is being used for intervention and stimulation operations in the Gulf of Mexico (GOM), and drilling long, extended reach (ER) wells with wired telemetry drill pipe in the Middle East. This paper presents the phases of the grade development and discusses testing requirements for the crossover between strength and SSC resistance. It also includes statistical data on the first full scale manufacturing tests. Finally, it outlines the products expectations for field applications.

The term "sour" is used to refer to drilling environments containing hydrogen sulfide (H2S). In sour wells, H2S causes sulfide stress cracking (SSC) in carbon low-alloy steels under tensile stress. A form of hydrogen embrittlement, SSC causes sudden, brittle fracture in drillpipe. To combat the effects of H2S exposure, sour service drillpipe has been manufactured to meet IRP Volume 1 - Critical Sour Drilling specifications. IRP requires 75 ksi (SS75), 95 ksi (SS95), or 105 ksi (SS105) tubes with all three grades using 110 ksi SMYS tool joints for use in sour operations. However, these lower yield strength IRP grades have limited load capacity which restricts drilling parameters such as total depth (TD) and margin of overpull. Using advanced steel heat treatment methods, a 125 ksi SMYS grade sour service drillpipe has been developed. The 125 ksi tube is mechanically incompatible with the standard 110 ksi IRP sour service grade tool joint because of the large difference in yield strength between the two components. Therefore, a new class of sour service tool joint with an SMYS of 120 ksi was required for the 125 ksi sour service tube. This new higher yield strength tool joint needs to meet the same level of SSC-resistance as the 110 ksi IRP tool joint, i.e., pass testing in solution A method A of NACE TM0177 (100% H2S @pH = 2.7, 720 hour test) at a testing stress of 65% of SMYS. Like the high yield strength 125 ksi tube, advanced heat treatment methods were required to achieve SSC-resistance in the higher yield strength tool joint. A second application for the 125 ksi drillpipe is as an offshore drillpipe-based intervention riser for non-sour wells. Currently, 105 ksi drill pipe grades are often used but increased demands on load capacity (up to 1,000 kips) makes the 125 ksi drillpipe an attractive alternative. The 125 ksi drillpipe also meets recommended hardness limitations placed on offshore risers in specification API RP 17G (Recommended Practice for Completion/Workover Risers). This paper introduces an SSC-resistant 125 ksi drillpipe with SSC-resistant 120 ksi tool joints and presents the results of NACE TM0177 testing of this new technology. The new 125 ksi drillpipe will allow for increased load capacity over IRP SS105 ksi grade drillpipe in drilling environments with moderate to low concentrations of H2S. In addition, it can serve as an improved substitute over 105 ksi drillpipe-based offshore intervention risers due to its increased load capacity and controlled hardness.

Sour gas constitutes 60% of the Middle East natural gas reserves (Nersesian 2015). The term "sour" is used to refer to environments containing hydrogen sulfide (H2S). In sour wells, H2S causes sulfide stress cracking (SSC) in carbon low-alloy steels under tensile stress. A form of hydrogen embrittlement, SSC causes sudden, brittle fracture in drillpipe. To combat the effects of H2S exposure, sour service drillpipe has been manufactured to meet IRP Volume 1 - Critical Sour Drilling specifications. IRP requires SS75 ksi, SS95 ksi, or SS105 ksi specified minimum yield strength (SMYS) tubes with all three grades using 110 ksi SMYS tool joints for use in sour operations. However, these lower yield strength IRP grades have limited load capacity which restricts drilling parameters such as total depth (TD) and margin of overpull. The next higher yield stress grade available is the API S135 grade. This grade is a non-sour service grade with SSC-resistance limitations due to its higher hardness and higher yield strength values. The SSC-resistance of S135 in an H2S drilling environment is dependent on using drilling muds with pH control (above 10.0), H2S inhibitors, and H2S scavengers. Therefore, a grade of SSC-resistant drill pipe is needed to bridge the gap between the fully SSC-resistant SS105 grade and limited SSC-resistant S135 grade. Using advanced steel heat treatment methods, a 125 ksi SMYS grade sour service drillpipe has been developed. The 125 ksi tube is mechanically incompatible with the standard 110 ksi IRP sour service grade tool joint because of the large difference in yield strength between the two components. Therefore, a new class of sour service tool joint with an SMYS of 120 ksi was required for the 125 ksi sour service tube. This new higher yield strength tool joint needs to meet the same level of SSC-resistance as the 110 ksi IRP tool joint, i.e., pass testing in solution A method A of NACE TM0177 (100% H2S @pH = 2.7, 720 hour test) at a testing stress of 65% of SMYS. Like the high yield strength 125 ksi tube, advanced heat treatment methods were required to achieve SSC-resistance in the higher yield strength tool joint. This paper introduces an SSC-resistant 125 ksi drillpipe with SSC-resistant 120 ksi tool joints and presents the results of NACE TM0177 testing of this new technology. The new 125 ksi drillpipe will allow for increased load capacity over IRP SS105 grade drillpipe in drilling environments with moderate to low concentrations of H2S. In addition, it can serve as an improved substitute over S135, a non-sour service grade drillpipe.