Best practice for offshore platform deformation survey using global navigation satellite system

Abstract

Offshore Platforms are one of the most important assets for Oil and Gas Company, and PETRONAS (Malaysia National Oil Company) is no exemption. Offshore platform started to be built around 1970s in the Malaysian waters and some of these platforms are still in production until today. Due to the age of some of these platforms that are already exceeding 30 years, there are issues with the structural integrity, thus the necessity for measurement and assessment have arisen. Pulai-A platform, one of PETRONAS platform located offshore Terengganu falls into this category. The method chosen in this research for the platform survey is Global Navigation Satellite System (GNSS), a highly precise solution to accurately demonstrate the real platform movement in three dimensions with a proven track record and rapid emergence of geodetic technologies and infrastructures in the global scale. The main objective of this research is to analyze in details the two different survey campaigns carried out using different GNSS methodology in 2006 and 2012. The research methodology used is by comparing the differences in the GNSS data acquisition, processing and results between these two epochs. There is also a study on project management impact for different GNSS technical approach, on how the new technique could save cost and time. After the analysis, results show that up to 80% cost-saving and 50% time-saving could be achieved by applying the new GNSS development into the survey process. The research concludes that application of improved GNSS methodology would certainly improve results and project quality. A best practice on how to use GNSS method to measure old and existing offshore platforms is proposed, based on the improvement applied in the 2012 campaign compared to the more conventional methodology in 2006. The proposed best practice is meant to be the pioneer in a more formal guidelines establishment for offshore platform survey using GNSS methodology in the future.