Development and Qualification of a Next Generation Gas Tight Connection Incorporating Metal-to-Metal Technology

Abstract

Abstract The Oil & Gas industry has an increasing demand for gas tight connections, particularly in deepwater applications such as in the Gulf of Mexico. These connections incorporate metal-to-metal seals and have been been motivated by wells requiring high-pressure completions/stimulations, drill stem testing, managed pressure/under-balanced drilling applications and wellbore cleanout assemblies. In response to customer requests, a new gas tight connection with a metal-to-metal rotary seal was developed. When developing this connection with high pressure gas tight capability, a no compromise approach was mandatory since safety and well integrity were primary concerns. This product can be utilized for both drilling and completion operations, so it represents a considerable cost saving due to improved operational efficiency. This paper details the development and qualification of this new connection. In the development of this new connector Finite Element Analysis (FEA) was used, resulting in a product that is a hybridized version of a premium double shoulder connection and the gas tight 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, a staunch safety commitment has allowed it to provide one of the highest operating margins of any gas tight connection and is qualified to 30,000 psi internal pressure and 25,000 psi external pressure. The full qualification results are detailed and discussed in the following pages.