Eight of the world's ten longest wells have been drilled by ExxonMobil as operator of the Sakhalin-1 project in Russia. Drilled from shore by one of the largest and most powerful land rigs in the industry, wells extend horizontally under the sea floor approximately 11 kilometers (7 miles). Using the Operator's redesign methodology, post well reviews are conducted after each well is drilled and completed to identify the key limiters to drilling performance. Components and drilling tools involved in the well design are evaluated and re-designed throughout the drilling program to maximize penetration rate and reduce flat time. This paper will provide an overview of how drill string torque capacity became a limiter to increasing penetration rate and limited the Operator from extending their total measured depth capability. This limiter necessitated that the operator seek an alternate drill pipe connection with higher torque capacity. The design of the new drill pipe connection and results to date from field implementation will be presented.
The drilling tubular connection evolution described in this paper highlights the need for continuous technology development to further increase the Extended Reach Drilling (ERD) envelope.
Utilizing an evolutionary connection design allowed interchangeability with existing drill pipe, accessories, and tools while providing 26% more torque capacity. Comparative fatigue testing demonstrates that the design will provide equal or better fatigue life when compared to the existing conection even while operating at a higher stress level. Deployed for approximately 18 months, initial field performance of the new connection has allowed the Operator to drill with higher continuous drilling torque while maintaining compatibility between the new and old drill pipe connnections.
ERD has become a commonly used technique to economically access reserves using existing infrastructure. A key ERD drilling challenge is the large amount of friction imposed by the wellbore on the drill string that results in high torque. Technologies that increase overall system torque capacity allow the Operator to drill faster, farther, and access more reserves.