Pushover Analysis Of Ageing Offshore Jacket Platform In Shallow Water Under Extreme Storm And Mitigation Strategy For Platform’s Life Extension

Setiawan, Budi (2025) Pushover Analysis Of Ageing Offshore Jacket Platform In Shallow Water Under Extreme Storm And Mitigation Strategy For Platform’s Life Extension. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Banyak platform jaket lepas pantai di seluruh dunia telah mendekati atau bahkan melampaui umur desain aslinya, tetapi masih digunakan dan tetap produktif. Sesuai dengan peraturan (code) internasional, standarisasi, dan praktik di industri, penilaian struktural terhadap platform jaket lepas pantai yang menua harus dilakukan berdasarkan nilai target yang relevan untuk menentukan apakah platform tersebut masih layak digunakan atau apakah perlu dipertimbangkan tindakan pengurangan risiko guna melanjutkan operasinya. Penelitian ini mengkaji perilaku runtuhnya (collapse) platform jaket lepas pantai yang menua dalam kondisi badai ekstrem, yang dapat membantu dalam menentukan strategi mitigasi yang paling sesuai untuk memperpanjang umur layanan platform. Analisis keruntuhan (collapse) non-linear telah dilakukan untuk menilai integritas dan keandalan struktural platform jaket lepas pantai di perairan dangkal dalam kondisi badai ekstrem. Dalam penelitian ini, dipilih dua platform dengan tipe tripod dan satu platform dengan tipe jacket berkaki empat dengan kedalaman air antara 30 hingga 80 meter yang berlokasi di Delta Mahakam, Kalimantan, Indonesia, sebagai model wellhead platform yang umum dibangun di perairan dangkal. Studi sensitivitas dilakukan untuk meneliti pengaruh interaksi pile dengan tanah, variasi kedalaman pile, penyesuaian beban topside, penghilangan marine growth, dan penguatan jaket terhadap kinerja struktural. Dari perspektif integritas dan keandalan struktural, temuan penelitian ini menunjukkan bahwa penguatan jaket dengan menambahkan soldier pile merupakan pendekatan paling efektif untuk memperpanjang umur layanan platform, terutama untuk platform yang didominasi oleh beban gelombang. Selain itu, analisis kelayakan biaya disarankan untuk evaluasi lebih lanjut guna menentukan apakah penguatan jaket merupakan pilihan yang layak atau apakah strategi pengurangan risiko alternatif perlu dieksplorasi lebih lanjut untuk platform lepas pantai yang menua.
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Many offshore jacket platforms worldwide have approached or exceeded their original design life but are still in use and productive. According to the international codes, standards, and industry best practices, structural assessments of ageing fixed offshore jacket platforms shall be conducted against relevant target values to assess whether it is fit for purpose or risk reduction measures should be considered for continuing its operation. This research examines the collapse behaviour of an ageing offshore jacket platform under extreme storm conditions, which can help to decide the most suitable mitigation strategy for extending the platform's lifespan. Nonlinear collapse analysis has been performed to assess fixed offshore jacket platforms' structural integrity and reliability in shallow water under extreme storm conditions. Two tripods and 4-legged jacket platforms at water depths between 30 to 80 meters, located in the Mahakam Delta, Kalimantan, Indonesia, have been selected in this research as wellhead platform models commonly installed in shallow water. Sensitivity studies examine the effects of pile-soil interaction, variations in pile depth, topside load adjustments, marine growth removal, and jacket strengthening on structural performance. From the structural integrity and reliability perspective, the findings highlight that strengthening the jacket by adding soldier piles is the most effective approach for extending the platform's lifespan, especially for a wave-dominated platform. Additionally, a cost feasibility analysis is advised for future evaluation to determine whether jacket strengthening is viable or if alternative risk reduction strategies should be further explored for the ageing offshore platform.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Platform Jaket Lepas Pantai yang Menua, Strategi Mitigasi, Probabilitas Kegagalan, Integritas Struktur, Keandalan Struktur, Perpanjangan Umur Platform ======================================================================================================================== Ageing Offshore Jacket Platform; Mitigation Strategy; Probability of Failure; Structural Integrity; Structural Reliability; Platform Life Extension
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC1665 Offshore structures--Materials.
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38101-(S2) Master Thesis
Depositing User:	Budi Setiawan
Date Deposited:	03 Feb 2025 02:44
Last Modified:	03 Feb 2025 02:44
URI:	http://repository.its.ac.id/id/eprint/117722

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