Analisis Tegangan Lokal Pada Sambungan Kritis Jacket Minimalis 3 Kaki

Noviyanti, Irma (2021) Analisis Tegangan Lokal Pada Sambungan Kritis Jacket Minimalis 3 Kaki. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Seiring berlajannya waktu, proses eksplorasi migas yang sebelumnya bisa dilaksanakan pada medan yang mudah dijangkau, mulai berpindah pada area-area yang bersifat remote serta dengan kandungan reservoir sedikit sehingga umur produksi yang dimiliki relatif pendek. Lapangan migas dengan kriteria tersebut dinamakan lapangan marjinal. Dalam pengembangan lapangan marjinal, perlu perencanaan strategis agar proses produksi tetap dapat menghasilkan keuntungan. Dalam rangka meningkatkan rate of return (ROR) dari pengembangan lapangan marjinal, salah satunya adalah dengan memodifikasi anjungan produksi seperti jacket. Modifikasi jacket berdampak pada menurunnya biaya konstruksi maupun instalasi sehingga persentasi ROR yang direncanakan dapat dicapai. Studi mengenai jacket modifikasi atau minimalis ini sebelumnya telah dilakukan oleh Giffary (2020). Dalam studi tersebut, dilakukan perbandingan umur kelelahan antara jacket konvensional dengan jacket minimalis. Dari hasil analisis, disimpulkan bahwa umur kelelahan jacket minimalis jauh lebih rendah dari jacket modifikasi. Namun, nilai SCF serta umur kelelahan ini didapat dari analisis global. Oleh karena itu, pada Tugas Akhir ini akan dilakukan analisis lokal untuk mendapatkan distribusi tegangan serta SCF pada sambungan kritis. Dari proses analisis, diperoleh SCF dari analisis lokal nilainya lebih besar 320% dibandingkan dari hasil analisis global dengan masing-masing tipe pembebanan berupa gaya aksial, inplane bending moment, dan outplane bending moment. Untuk distribusi tegangan yang terjadi, berdasarkan tipe pembebanan gaya aksial, hotspot stress terjadi pada brace 3 dan terletak pada crown toe. Pada tipe pembebanan inplane bending moment, hotspot stress terjadi pada brace 6 yang terletak pada crown toe. Sedangkan pada tipe pembebanan outplane bending moment, hotspot stress terjadi pada brace 4 yang terletak pada crown heel. Selanjutnya, dilakukan studi parametrik dengan variasi parameter non dimensional sambungan tubular pada tipe pembebanan gaya aksial, inplane bending moment, dan outplane bending moment. Diperoleh hasil yang menunjukkan bahwa semakin tinggi parameter ß, hotspot stress yang terjadi akan turun. Sebaliknya, semakin tinggi parameter τ, hotspot stress yang terjadi akan semakin tinggi pula.
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As time goes by, the process of oil and gas exploration which previously conducted in the accessible area is slowly moving to the area which stated as remote. This kind of field only hold a small amount of reservoir which makes the production period occurs in a short way. Oil and gas field which hold those criterias is defined as marginal field. The development itself requires some strategic plannings in order to still generates profit over its production process. To increase the rate of return (ROR) value from the marginal field development, on of the strategy is to modify the production platform such as jacket. Modification in jacket will give affects in the reduction cost on both fabrication and installation phase. The study of modified or minimalist jacket has been taken before by Giffary (2020). In those study, a comparison of the fatigue life between conventional and minimalist jackets was carried out. From the analysis, it was concluded that the fatigue life of the minimalist jacket is much lower than that of the minimalist jacket. However, the SCF value and fatigue life were obtained from global analysis. Therefore, in this final project, a local analysis will be carried out to obtain the stress distribution and SCF at the critical connection. From the analysis process, the SCF value obtained from the local analysis is 320% greater compared to the results of the global analysis with types of loading consists of axial force, inplane bending moment, and outplane bending moment. For the stress distribution occured, based on the axial force loading type, the hotspot stress occurs at brace 3 and is located at the crown toe. In the inplane bending moment loading type, hotspot stress occurs in brace 6 which is located at the crown toe. Whereas in the outplane bending moment loading type, hotspot stress occurs at brace 4 which is located on the crown heel. Furthermore, a parametric study was also performed with variations in the non-dimensional parameters of tubular joints in the type of axial force loading, inplane bending moment and outplane bending moment. The results show that the higher the ß parameter, the hotspot stress that occurs will decrease. On the other hand, the higher the τ parameter, the higher the hotspot stress will occurs.

Item Type:	Thesis (Undergraduate)
Uncontrolled Keywords:	minimalist jacket, critical joint, local stress, SCF, hotspot stress, jacket minimalis, sambungan kritis, tegangan lokal, SCF, hotspot stress.
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:	Irma Noviyanti
Date Deposited:	02 Mar 2021 04:21
Last Modified:	02 Mar 2021 06:27
URI:	http://repository.its.ac.id/id/eprint/83150

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