The petroleum industry has a growing need for gas tight solutions which have been motivated by wells requiring drill stem testing, high-pressure completions/fracturing jobs or managed pressure/under-balanced drilling operations. The main advantage of using a drillstring with gas tight properties is that it allows operators to save time while minimizing the risk of damaging the connection. Safety and well integrity concerns further accentuate the need for a connection with gas tight capability.
A new high pressure-rated rotary-shouldered connection with a metal-to-metal seal has been developed and tested up to 30ksi internal working gas pressure and 25ksi external gas pressure. This premium high-pressure connection allows the same drillstring to be utilized for both drilling and completion operations, representing a considerable cost saving over conventional industry practice. This paper details the development and qualification of this new double-shoulder gas tight connection for drilling and other drillpipe based applications.
Several concepts were assessed by FEA and the final solution involved a hybridized version of a premium high torque rotary connection and an adaptation of the connection from a drill-pipe-riser. The connection therefore provides the high pressure capability of premium casing or tubing connections coupled with the robustness and increased torsional strength associated with a double shoulder rotary connection. Qualification of the new product was performed on the most critical sizes and involved industry standard physical testing.
Gas tight solutions are used for most of the deep offshore wells in the Gulf of Mexico and it is expected that in upcoming years it will be deployed in other deep offshore markets.
