China oil and gas operators are more and more engaged in the exploration and production of much deeper oil and gas prospects that are pushing the boundaries and limits of the traditional drill stem. A high number of ultra-deep wells (above 7 000 meters) are being drilled in the Xinjiang area. In this part of China, there is a need to improve the hydraulic and mechanical performances of the drilling tubulars used in both large and slim hole size intervals.
A key feature in these products’ performances is the rotary shouldered connection (RSC). API RSC typically requires larger profiled tool joints to provide acceptable torque and tension capacity. However, this increase s pressure losses and restricts fishability. Double shoulder connection (DSC) technology has been successfully used to address this mutually exclusive need for both torque and hydraulics.
CNPC has greatly benefited from their decision to use a first generation double shoulder connection (1st gen DSC) on various sizes of drilling tubulars to successfully drill the deepest exploration well in the Jungar basin as well as numerous exploration and production wells in the Tarim basin.
This paper will first describe the DSC technology, how it contributes to the improved drilling performance, and will present supportive case histories. The 1st gen DSC performed very successfully. Looking ahead, deeper prospects are on the horizon and further enhancements in drill pipe and DSC technology will be necessary. Prospective future options will also be discussed in this paper.