Arthur Lubinski Best ASME Mechanical Engineering Paper Presented at OTC 2015.

The oil and gas industry is targeting operations in much deeper waters and well depths resulting in high pressure and high temperature (HPHT) applications, creating a need for development of new technology to meet the challenges faced in these new frontiers. Considering the higher loads encountered in these environments, the existing industry equipment are reaching their limits and the manufacturing sector is looking into the development of the next generation equipment. Subsea wellheads form a critical part of the drilling and production systems, and they are the driver for designing and sizing other equipment, such as connectors, risers, BOPs, and casing programs. The typical wellhead systems that the industry currently uses include mandrels with 27 in. and 30 in. OD and conductor casing with up to 36 in. OD. However, these configurations may not be able to resist the high load magnitudes and combinations expected in these new applications. Moving to higher capacity wellhead systems will require a larger mandrel and conductor casing size to accommodate the high loads encountered during drilling and production operations for normal, extreme, and survival loading conditions. Considering the ongoing industry efforts to standardize equipment, it is a great opportunity to define the anticipated loads and select an appropriate larger wellhead size that will cover the needs of the industry for the coming decades. Numerous analytical studies using 3D finite element analysis (FEA) and other advanced tools have been performed looking into the changes needed and an innovative solution is presented for the next generation subsea wellhead equipment. This is tied with the development of new wellhead connectors with much higher static capacities and the appropriate conductor sizes needed. Considerations are given to structural integrity, fatigue performance, and metal-to-metal sealing capability. Various load combinations (bending, tension/compression, pressure) were applied to generate the wellhead system capacity envelopes covering a wide range of operating windows. The need for the industry to define the anticipated normal, extreme and survival loading requirements and a standard set of fatigue loads is discussed. The fatigue performance and life expectancy of the equipment, as well as challenges faced with the lack of material properties at various HPHT environments are discussed. Testing facilities to validate designs and safety margins at both component and system levels have been developed to accommodate the various high load magnitudes and their combinations. Validation testing is absolutely paramount to verify analysis methodologies and ensure high performance, safe, robust and reliable equipment designs. [ABSTRACT FROM AUTHOR]