Desain dan Analisis Upending Struktur Jacket Tiga Kaki di Perairan Selat Makassar
Design and Upending Analysis of Three-legged Jacket Structure in Makassar Strait
Muchamad Raihan Nafis 1 dan Prof. Dr. Ir. Ricky Lukman Tawekal 2
Program Studi Teknik Kelautan
Fakultas Teknik Sipil dan Lingkungan, Institut Teknologi Bandung,
Jl Ganesha 10 Bandung 40132
1 rnafis24@students.itb.ac.id dan 2 ricky@ocean.itb.ac.id
ABSTRACT Onshore oil and gas reserves are increasingly scarce. The exploration of the primary
energy source has begun to shift to the offshore area. Offshore platform is one of the supporting facilities
for the upstream oil and gas industry. Offshore platform structures need to be carefully designed, to
ensure safe operations on the structures. In this final project, a three-legged fixed jacket platform is
designed to operate in the Makassar Strait. The structure is designed according to the API RP2A – WSD
standard. The offshore platform structure design has to be assessed in terms of serviceability of the
structure due to loading in the field. Initial assessment of the structure includes in-service analysis (inplace,
seismic and fatigue analysis). From the analysis result, can be concluded that the designed
structure is able to withstand operating and storm condition according to the results of in-place analysis,
through checking member stress, deflection, joint can and pile capacity. The designed structure is also
considered to be able to accommodate earthquake strength level (SLE) and rare intense (RIE)
earthquake conditions, by checking the member stress, joint strength (joint can) and pile capacity. Also,
the structure can last for 23.49 years (with a safety factor of 5.00) with a fatigue damage of 0.639 from
the fatigue analysis result.
After the structure is declared feasible to operate in the field, pre-service analysis is carried out in the
form of lifting analysis on the topside and floatation and upending analysis on the jacket. The designed
topside structure is able to meet the stress criteria of the API RP2A – WSD design criteria in both
balanced and unbalanced lifting configurations. The entire design and selection of lifting components
including sling rope and shackle properties, also dimensions of the padeye have also met the API RP2A
– WSD design standard. Floatation and upending analysis was carried out to obtain a feasible scenario
for upending activities based on the GL Noble Denton 0028/ND Guidelines for Steel Jackets
Transportation and Installation criteria. Upending scenario was obtained with a combination method
of controlled ballasting from the buoyancy tank and crane vessel lift. The buoyancy tank functions as
an upending force, while the crane hook functions as a jacket load-controller. This scenario has met the
criteria for seabed clearance and minimum stability of the GL Noble Denton 0028/ND criteria. Based
on the force acting on the main hook during the upending process, the Bokalift 1 DP-2 3000 T vessel
crane was selected with a maximum capacity of 1,200 MT for its main hook. It is concluded that the
fixed platform structure of the three leg jacket type in this Final Project also meets the criteria at the
pre-service analysis stage.
Keywords: Platform, in-place, seismic, fatigue, lifting, floatation, upending.
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