Analisis Interferensi Flexible Dynamic Riser Terhadap Umbilical dengan Variasi Konfigurasi Lazy-Wave

Khalida, Advira Nafi (2025) Analisis Interferensi Flexible Dynamic Riser Terhadap Umbilical dengan Variasi Konfigurasi Lazy-Wave. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Studi ini berkaitan fenomena interferensi antara flexible dynamic riser terhadap umbilical. Studi kasus merupakan proyek PT. XYZ yang berlokasi pada Yoho Field, Nigeria. Adapun struktur yang terpaut berupa vessel. Konfigurasi sistem risers pada studi ini memiliki profil lazy-wave pada lautan dengan kondisi shallow (dangkal). Pada studi ini, penulis akan memeriksa minimum line clearance dan minimum bending radius antar komponen risers berdasarkan interaksi hidrodinamis antar risers. Adapun parameter dalam analisis ini akan mengikuti standar API RP-17J dan DNV F-203 dalam kondisi unbounded dan prinsip desain no-collision-allowed untuk menghindari fenomena clashing. Dalam mengamati hal tersebut, analsisis dinamis sistem telah dilakukan untuk terlebih dahulu. Hasil menunjukkan bahwa arah kritis respon dinamis berada pada 90° untuk moda Sway, Heave, dan Roll, dengan RAO yang tinggi pada moda Roll dan Heave, menandakan dominasi respons lateral yang memerlukan mitigasi risiko. Moda Surge dan Pitch cenderung stabil kecuali pada arah longitudinal, sementara moda Yaw memiliki pengaruh signifikan pada arah diagonal (60° dan 120°). Sistem tambat memenuhi standar API RP 2S dengan safety factor 1,7–1,8, dan line paling kritis adalah line 1 dengan tegangan maksimum 7108,48 kN. Flexible dynamic riser dan umbilical menunjukkan kondisi paling kritis pada skenario ballasted dan posisi vessel far, namun tetap berada dalam kapasitas aman dengan tegangan maksimum 220,1 kN, jauh di bawah batas desain 2000 kN, bahkan pada kondisi damaged mooring. Analisis interferensi menunjukkan minimum line clearance sebesar 0,334 m pada kondisi intact dan 0 m (kontak) pada kondisi damaged. Variasi distribusi buoyancy clamp tipe uniform memberikan probabilitas interferensi lebih rendah (<40%) dibandingkan tipe clustered (60%). Namun, konfigurasi lazy wave dengan tiga line masih menunjukkan kejadian clashing pada berbagai variasi buoyancy module dan separation angle, sehingga dianggap kurang aplikatif.
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This study focuses on the interference phenomena between flexible dynamic riser and umbilical. The system analyzed is taken from the study case of PT. XYZ's project located in the Yoho Field, Nigeria. The system configuration is a vessel with external turret that connected with a tethered lazy wave flexible riser and umbilical located in 65 m water depth. This study examines the minimum line clearance and minimum bending radius of each line, considering hydrodynamic interactions between risers. The parameters for this analysis adhere to the standards outlined in API RP-17J and DNV F-203, under unbounded conditions and the no-collision-allowed design principle to prevent clashing between the lines. Therefore, a complete dynamic system analysis was conducted to investigate all the aspects. The results indicate that the critical response direction is at 90° for the Sway, Heave, and Roll modes, with vessel’s high RAO values observed in the Roll and Heave modes, giving significant dominant lateral responses to the vessel response thus further risk mitigation is required. The Surge and Pitch modes tend to remain stable, except along the longitudinal direction, the Yaw mode exhibits a relatively minor except significant influence at diagonal directions (60° and 120°). The vessel mooring system satisfies the standards set by API RP 2S, with a safety factor ranging from 1.7 to 1.8. The analysis results shows that mooring line-1 is the critical mooring line with maximum tension of 7108.5 kN. The flexible dynamic riser and umbilical experience their most critical conditions during the ballasted scenario and the vessel far position. However, they remain safe within both intact and damage mooring condition, with a maximum tension of 220.1 kN, below the design limit of 2000 kN. Interference analysis reveals a minimum line clearance of 0.334 m under intact conditions and 0 m (contact) under damaged conditions, though no significant collision energy is observed. Variations in buoyancy clamp distribution indicate that the uniform type achieves a lower interference probability (<40%) compared to the clustered type (60%). In addition to that, the lazy-wave configuration with three lines continues to exhibit clashing incidents across various buoyancy module and separation angle variations, rendering this configuration less practical for such applications.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	flexible dynamic riser, interferensi, lazy-wave, umbilical, interference.
Subjects:	T Technology > TC Hydraulic engineering. Ocean 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:	Advira Nafi Khalida
Date Deposited:	23 Jan 2025 07:27
Last Modified:	23 Jan 2025 07:27
URI:	http://repository.its.ac.id/id/eprint/116745

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