Best Engineering Practices in Standardization of Offshore Wellhead Tower Design – EPC Contractor’s Experience

The wellhead tower facilities in Offshore are designed to receive well fluid from different oil fields and transport through pipelines for further processing. The functional requirements for any typical wellhead tower do not vary much; leading to similar design features in most of the Offshore facilities. This paper discusses the best practices applied in standardization of Offshore wellhead tower’s design and highlights its advantages in execution of EPC projects. In the standardized design, the sizing of equipment and piping for a wellhead tower are normally pre-defined and fixed for all new projects. The pre-defined design specifications are finalized based on best engineering practices and field experiences. For example; the well flow line size of about 6" is found sufficient for typical oil production platforms as well as meets conventional line sizing criteria for most of the projects. Similarly, the material of construction for all piping and equipment can also be pre-selected as part of the standardized design for all new wellhead towers. The execution of an EPC project from detailed design stage to commissioning, within a given schedule is essential for success of any project. In conventional design approach, various design activities for a wellhead tower such as engineering calculations, design verification and specialized engineering studies are repeated for each project even though the design is already pre-fixed. This is a time-consuming approach and takes significant amount of time without any value addition. This also delays the procurement activities leading to cascading effect on fabrication, installation and commissioning of the facilities. In the standardized approach, design details such as equipment/line sizes, layout is already finalized and EPC contractor is mainly required to update engineering deliverables based on the vendor design information/details. This approach significantly reduces the project schedule. The standardized approach provides an opportunity for fast-track execution of the projects. In addition, it leads to better management of material resulting in reduced maintenance and shutdown period during operational phase. The standardized design also provides flexibility to the operator for easy maintenance and operation of the similar facilities at other locations. NPCC has recently successfully executed many wellhead tower projects involving standardized design approach. Based on the experience gained and the lessons learnt through these projects, NPCC proposes the best engineering practices that can be adopted for the execution of standardized offshore wellhead towers design providing benefits to all stakeholders.