Analisis Risiko Keruntuhan Jacket Wellhead Tripod Platform Pasca Subsidence

Aulia, Anggi (2023) Analisis Risiko Keruntuhan Jacket Wellhead Tripod Platform Pasca Subsidence. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Selain terjadi di kota-kota besar, subsidence juga bisa terjadi di sekitar daerah eksploitasi minyak dan gas bumi baik onshore maupun offshore. Indikasi penurunan tanah
dapat dilihat dari terjadinya penurunan anjungan lower deck yang semakin tenggelam secara fisik. Terjadinya subsidence dapat menyebabkan kegagalan struktur. Apabila terjadi kegagalan, struktur dapat mengalami berbagai kemungkinan konsekuensi yang bisa menimbulkan bahaya hingga kerugian. Mengingat konsekuensi dan kerugian yang mungkin terjadi, maka perlu dilakukan analisis risiko pada struktur dengan variasi kedalaman subsidence hingga struktur mengalami keruntuhan. Analisis keruntuhan dilakukan dengan meningkatkan beban lingkungan kondisi badai secara bertahap hingga struktur mengalami keruntuhan karena terbentuknya member plastis. Member plastis akan digunakan dalam analisis keandalan, dimana peluang kegagalan member dihitung dengan simulasi Monte Carlo dengan menggunakan Random Number Generator (RNG). Kemudian, keandalan sistem dihitung menggunakan Reliability Block Diagram (RBD) yang selanjutnya digunakan dalam analisis risiko. Kedalaman maksimum subsidence yang diizinkan agar struktur masih layak beroperasi sesuai API RP 2A WSD 21st edition adalah sebesar 5.2 meter dengan Reserve Strength Ratio (RSR) terkecil yakni 1.85. Analisis keandalan dilakukan untuk kondisi non subsidence hinga kondisi subsidence 5.2 meter dengan keandalan sistem terkecil sebesar 0.564 dan Probability of Failure (PoF) sebesar 0.436. Berdasarkan matriks risiko, diperoleh hasil bahwa struktur untuk kondisi non-subsidence dan subsidence pada konsekuensi safety keduanya berada di area kuning yang berarti medium risk merupakan daerah as low as reasonably practicable (ALARP), sedangkan untuk konsekuensi environment dan business berada di area merah yang berarti high risk.
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Apart from occurring in big cities, subsidence can also occur around oil and gas exploitation areas, both onshore and offshore. Indication of land subsidence can be seen
from the condition in the lower deck platforms which are physically sinking. The occurrence of subsidence can cause structural failure. In the event of a failure, the structure may experience various possible consequences which can result in a hazard or loss. Consideringthe consequences and losses that may occur, it is necessary to carry out a risk analysis on the structure with variations in the depth of subsidence until the structure collapses. The collapse analysis is carried out by gradually increasing the environmental load under storm conditions until the structure collapses due to the formation of plastic members. Plastic members will be used in the reliability analysis, where the probability of member failure is calculated using a Monte Carlo simulation using a Random Number Generator (RNG). Then, system reliability is calculated using the Reliability Block Diagram (RBD) which is then used in risk analysis. The maximum depth of subsidence allowed for the structure to still be operational according to API RP 2A WSD 21st edition is 5.2 meters with the smallest Reserve Strength Ratio (RSR) of 1.85. Reliability analysis was carried out for nonsubsidence condition up to 5.2 meters subsidence with the smallest reliability of 0.564 and Probability of Failure (PoF) of 0.436. Based on the risk matrix, the result show that the structure for the non-subsidence and subsidence conditions are both for safety consequences is in the yellow area, which is means medium risk also known as an area as low as reasonably practicable (ALARP), while for environmental and business consequences are in the red area, wich means high risk.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	ALARP, Keruntuhan, Monte Carlo, Reliability Block Diagram, Subsidence
Subjects:	T Technology > T Technology (General) > T174.5 Technology--Risk assessment. T Technology > TA Engineering (General). Civil engineering (General) > TA169 Reliability (Engineering) T Technology > TA Engineering (General). Civil engineering (General) > TA645 Structural analysis (Engineering) T Technology > TC Hydraulic engineering. Ocean engineering > TC1680 Offshore structures
Divisions:	Faculty of Marine Technology (MARTECH) > Ocean Engineering > 38201-(S1) Undergraduate Thesis
Depositing User:	Anggi Aulia
Date Deposited:	18 Jan 2023 03:25
Last Modified:	18 Jan 2023 03:25
URI:	http://repository.its.ac.id/id/eprint/95445

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