Geophysical and geotechnical surveys for offshore wind farm development: current context in Vietnam and essential recommendations

Abstract

Vietnam has an abundant offshore wind resources and offshore wind energy could play an important role in the goal Net-Zero Emission by 2050. In the near future, the roadmap of nearshore and offshore wind in Vietnam has detailed in PDP8 (May 2023) with potential installed capacity of 6,000 MW by 2030.

To design and construct an offshore wind farm, Geophysical survey and Geotechnical surveys are major activities besides Met-ocean investigation. Geophysical and geotechnical surveys need to be gradually performed from the Feasibility study (FS), (Conceptual design) FEED, Detailed Design, and Construction phase with appropriate in-situ tests and laboratory tests. Based on some geophysical and geotechnical survey reports for nearshore wind farm projects in Vietnam, it is found that their geophysical and geotechnical investigations did not follow the requirements of relevant international standards and have not been carried out with enough required numbers of tests and appropriate tests. Geophysical studies were only limited to the seabed topographical survey.

These geophysical and geotechnical investigations are based on some domestic standards for various sectors and did not follow some widelyused codes and design guidelines such as ISO 19901-8 (2014) [1], ISO 19901-10 (2021) [2], DNV-RP-C212 (2019) [3], guidelines of CFMS (2020) [4] and ISSMGE (2005) [5]. This paper aims to briefly show the current status of geophysical and geotechnical surveys for nearshore/offshore wind projects in Vietnam and summary essential requirements for
offshore wind turbine foundations and offshore sub-station foundations from international standards for the geophysical and geotechnical survey.

Keywords: Offshore wind; geophysical - geotechnical survey requirements; recommendations from Internaltional standards.