Development and Qualification of a New High Pressure Gas Tight Rotary Shouldered Connection Incorporating Metal-to-Metal Technology For Deepwater Drilling and Completion Applications

摘要

Deepwater drilling and completions operations particularly in the Gulf of Mexico have a growing need for gas tight connections incorporating a metal-to-metal seal. This has been motivated by wells requiring drill stem testing, high-pressure completions/hydraulic fracturing jobs or managed pressure/under-balanced drilling operations. Safety and well integrity concerns further accentuate the need for a no compromise approach when developing connections with gas tight capability. In response to these industry needs a new gas tight connection with a metal-to-metal rotary seal has been developed. This premium high-pressure connection allows the same drillstring to be utilized for both drilling and completion operations, representing a considerable cost saving and improved efficiency 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 Finite Element Analysis (FEA) and the final solution involved a hybridized version of a premium high torque connection and 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 including make & break, overtorque, combined loading and fatigue testing. In fact, it provides one of the highest operating safety margins of any gas tight connection and is qualified to 30,000 psi internal pressure and 25,000 psi external pressure. Results of the full qualification are presented and discussed below.