Development of the 18-3/4" – 20,000 psi Subsea Wellhead System for High Pressure and High Temperature Applications

Abstract

Abstract There is an increasing need for higher pressure and higher temperature rated equipment as wells are being drilled in such reservoirs in deep water subsea fields. This paper presents the development of the first 18-3/4" – 20,000 psi subsea wellhead system rated for 0°F to 350°F temperature applications utilizing high capacity running and specialty running tools. Included are details of the three year development project including component design, reliability analysis, and prototype testing of the equipment in the laboratory with simulated field conditions. With this technology, operators can explore fields while further completion technology is developed. This 20ksi subsea wellhead technology will enable operators to drill wells using 15ksi BOP stacks while the 20ksi BOP stack is under development. The wellhead system includes special provisions to enable annulus seal assemblies to be tested to 20ksi while isolating the BOP stack. Drilling into high pressure zones for logging or testing can be performed through a 13-5/8"-20ksi BOP stack which latches directly to the subsea wellhead. In synopsis, this paper highlights the wellhead system details utilized for extreme environments up to 350°F and up to 20,000psi working pressure. The goal of this paper is to open the industry's horizons to production fields and reservoirs that operators previously could not develop due to technological constraints such as the higher bottom hole pressures or greater well temperatures with existing subsea mudline wellhead equipment.