DESIGN AND ANALYSIS OF SUBSEA PIPELINE ON THE LATAU PROJECT IN NATUNA SEA

• Main Author: Ester Viola Lumbanraja, Beverly
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/86398
• Institution: Institut Teknologi Bandung

Oil and natural gas remain the primary sources for fulfilling national energy needs in Indonesia. This aligns with the significant production targets set by SKK Migas, namely, 1 million barrels of oil per day and 12 billion cubic feet of natural gas per day by 2030. Various efforts are being made, one of which is the exploitation of oil and gas from offshore wells. Therefore, the construction of adequate production facilities and infrastructure is necessary, including a subsea pipeline system, which plays a crucial role in the transportation of oil and gas. The construction of subsea pipelines requires a series of analyses and design stages to ensure pipeline safety. This was carried out in the Latau project, a conceptual project working on the construction of a 32.5 km subsea pipeline in the Natuna Sea. In this study, environmental data parameters were used in the form of probability distribution data that had previously been tested for goodness-of-fit using the Kolmogorov-Smirnov method as input data for the analysis and design stages. The pipeline route is divided into two zones with differences in current data and water depth. Zone 1 covers KP0-KP19, while Zone 2 covers KP19-KP32. The design stages begin with the design of the pipe wall thickness based on the DNV-ST-F101 standard. Then, the wall thickness analysis results based on DNV-ST-F101 were used to select the available wall thickness from the API 5L catalog, which is 12.7 mm. The next stage is an on-bottom stability analysis of the pipeline based on the DNV-RP-F109 standard. Based on this analysis, a 40 mm concrete layer thickness was obtained for both zones with the aid of trenching. Next, an installation analysis of the subsea pipeline was conducted based on the DNV-ST-F101 standard to ensure that the pipeline could be laid on the seabed using the Hafar Neptune-type lay barge. The installation analysis results provided the appropriate lay barge configuration so that the stress and strain on the pipeline did not exceed the limits according to the applicable criteria. The final stage of analysis in this study is the free span analysis of the subsea pipeline, which aims to determine the maximum allowable free span length to prevent pipeline failure, based on the DNV-RP-F105 standard. The analysis was conducted by considering the screening fatigue and ultimate limit state (ULS) criteria. The free span length that meets both criteria is 12.8 m.