Analisis Mooring System Pipelaying Barge Saat Kondisi Badai Dan Analisis Local Buckling Subsea Pipeline Pada Proses Abandonment And Recovery

Samudra, Alief Pratama (2025) Analisis Mooring System Pipelaying Barge Saat Kondisi Badai Dan Analisis Local Buckling Subsea Pipeline Pada Proses Abandonment And Recovery. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Instalasi pipa bawah laut merupakan tahapan penting dalam industri minyak dan gas lepas pantai, namun pelaksanaannya tidak lepas dari potensi gangguan salah satunya adalah cuaca buruk. Salah satu metode mitigasi terhadap gangguan tersebut adalah dengan melakukan prosedur abandonment and recovery, yaitu penurunan sementara pipa ke dasar laut untuk kemudian diangkat kembali setelah kondisi aman. Penelitian ini menganalisis dua aspek dalam prosedur tersebut yaitu mooring system pada pipelaying barge saat kondisi badai, dan analisis local buckling pada subsea pipeline selama proses abandonment and recovery. Analisis dilakukan dengan simulasi numerik menggunakan software MOSES untuk model barge dan sistem tambat, serta OFFPIPE untuk menganalisis tegangan pada pipa. Mooring System harus memenuhi kriteria keselamatan berdasarkan API RP 2SK dengan faktor keamanan >1.67 pada kondisi Ultimate Limit State (ULS). Kemudian analisis local buckling mengacu pada kriteria DNV OS-F101 dimana nilai UC <1. Pada analisis mooring system pipelaying barge saat kondisi badai didapatkan nilai yang mendekati SF terdapat pada titik top di arah gelombang 90° dengan nilai SF rata-rata mooring line starboard 1-4 sebesar 11 dan 270° nilai terbesar terdapat pada mooring line portside 1-4 dengan nilai rata-rata SF sebesar 11. Kemudian saat proses permodelan abandonment and recovery dilakukan dengan 3 variasi kedalaman laut yaitu 70 m,74 m dan 77 m pada masing- masing variasi panjang cable dimana cable 120 m pipeline berada di antara barge dan stinger, 130 m pipeline berada pada pertengahan stinger, 150 m pipeline berada diujung stinger, 180 m pipeline mulai meninggalkan stinger dan 220 m pipeline berada di pertengahan kedalaman laut, dan 300 m saat pipeline sudah berada di dasar laut. Kemudian pada perhitungan local buckling pada pipa di masing-masing kedalaman didapatkan nilai maksimum berada di titik sagbend saat pipa berada diujung stinger dengan nilai masing- masing 0,46, 0,49, 0,52
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Subsea pipeline installation plays a vital role in offshore oil and gas operations. However, its execution is susceptible to disruptions, particularly due to severe weather conditions. To mitigate such risks, abandonment and recovery procedures are implemented, temporarily lowering the pipeline to the seabed until it is safe to resume installation. This study aims to analyze the performance of the mooring system of a pipelaying barge under storm conditions, and the local buckling response of the subsea pipeline during the abandonment and recovery process. Numerical simulations were carried out using MOSES to model the pipelaying barge and mooring system, while OFFPIPE was used to assess stress and on the pipeline. Mooring system safety was evaluated based on API RP 2SK with a required safety factor (SF) > 1.67 under Ultimate Limit State (ULS) conditions. The local buckling criteria refer to DNV OS-F101, where the unity check (UC) must remain below 1.0. Under storm conditions, the lowest SF values occurred at the top mooring point in the 90° wave direction, with starboard mooring lines 1–4 averaging an SF of 11. Similarly, at 270°, portside lines 1–4 exhibited an average SF of 11. During the abandonment and recovery simulation, three water depths (70 m, 74 m, 77 m) and five cable lengths (120 m to 300 m) were modeled. The highest local buckling utilization was observed at the sagbend region when the pipeline was at the tip of the stinger, with UC values of 0.46, 0.49, and 0.52, respectively

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Mooring system, Pipelaying barge, Abandonment and recovery, local buckling
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User:	Alief Pratama Samudra
Date Deposited:	24 Jul 2025 04:10
Last Modified:	24 Jul 2025 04:10
URI:	http://repository.its.ac.id/id/eprint/120991

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