Breaking the Performance/Cost Paradigm in Drill Pipe Connections in Extended Reach Drilling

Abstract Various generations of double-shouldered drill pipe connections have been developed in the past 30 to 40 years with performance as a primary driver. The objective was to bring improvements in torque and hydraulics to satisfy drillers' needs. The record extended reach drilling (ERD) wells could not have been delivered without these technological advancements. The driver for these developments was solely on improved performances, with limited focus on cost, as these technologies were so enabling that the associated costs were deemed acceptable. When these same connections started to be used on land rigs to deliver wells in a factory drilling fashion, where cost control is of higher importance, the cost of maintaining these premium connections started to become more apparent. It, therefore, became obvious that a different approach was needed to meet the combined need for performance, as well as a lower cost of ownership post acquisition. A comprehensive two-year research and development (R&D) program was carried out to evaluate various design options. After the research was conducted, a design was chosen that allows better control of stress inside the connection. This allows users to benefit from other design features besides the torque and hydraulics of a streamlined connection. The R&D program included numeric simulation and mechanical lab testing. More specific elements of the design allowed more tolerance related to field damage of the connection, less material loss on repairs, and more importantly, a ruggedness so that the connection can remain in the field longer rather than needing to be repaired so often. The final stage of qualification was a field trial at the manufacturer's test rig facility. A post field trial inspection confirmed the improved serviceability and ruggedness, qualifying the connection for commercial release. The 4th generation double-shouldered connection was first put to task in the Permian basin. A rental string was dispatched to a land rig and used to drill the longest and fastest lateral in the area. The tapered 5½ in. by 5 in. drill pipe string, which comes with tool joints of a similar size (this of 5 in. drill pipe), drilled the well and saved two days off the estimated drilling plan. Subsequently, more strings have been deployed, and more data shall be gathered in this paper to demonstrate the low repair rate. A new approach has been used to design a connection that performs at high torque levels but also demonstrates improved serviceability and a ruggedness approaching that of an API rotary shoulder connection.