Design and reliability analysis of accommodation work barge mooring configuration at a tension leg platform in Makassar Strait, Indonesia

Antonio De Juan Juan ,Rildova Rildova,Paramashanti Paramashanti,Henry Setyawan

doi:10.1051/matecconf/201927001003

Antonio De Juan Juan , Rildova Rildova + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/201927001003

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Abstract

An Accommodation Work Barge in Makassar Strait attaches to a Tension Leg Platform (TLP), a floating offshore platform operating in deep-water oil and gas field for a well intervention project. The mooring system are tied up to the north mooring lines of the vessel, whilst hawsers from the TLP connected to the south lines of the vessel. The TLP is fitted with two “TH” lines on its south side. However, these “TH” lines fail due to the unknown reason. The purpose of this study is to evaluate mooring performances to support the TLP operation by using API RP2SK recommendation, which suggests line tension limit, TLP offset, and minimum clearance between facilities. This study assesses reliability index (β) of the recommended design to evaluate whether the TH lines are required or could be eliminated. Mooring analysis is performed using ORCAFLEX for intact and damaged condition, while Monte Carlo simulation is performed to get system failure probability with minimum breaking strength ratio (%MBS) as required parameter. From the results, it is found that TH lines could be eliminated, as they do not affect significantly to the system. The analysis delivers a very secure index (β=14.676) with probability of failure below 10-5.

Highlights

The purpose of this paper is to verify the mooring performances of the vessel connected to the Tension Leg Platform (TLP) in Makassar Strait, Indonesia and the impact of the mooring forces on the TLP offset performances
The analysis results present the maximum tension in the vessel and TLP mooring lines, the vessel and TLP offset and motions as well as the clearance between the two vessels
It is recommended to change the Accommodation Work Barge (AWB) mooring lines connected to the TLP with new IWRC 54mm wires with minimum breaking load (MBL) 174 tonnes from EEIPS 38 mm wires with MBL 90 tonnes [9]

Summary

Introduction

The purpose of this paper is to verify the mooring performances of the vessel connected to the TLP in Makassar Strait, Indonesia and the impact of the mooring forces on the TLP offset performances. More precisely to evaluate required mooring pattern, configuration, and properties, provide separation distance to ensure safe clearance between facilities, and provide recommendation as to whether TH mooring legs are required or could be eliminated. This study provide basis for required mooring accessories to be prepared. One criteria in designing a floating offshore structure is about its mooring system [1,2]. A Tension Leg Platform (TLP) as one of the floating offshore oil and gas platform is suit to operate in deep water (1000 m – 1500 m). A well intervention usually needed to make an improvement to the well. This long process needs extra facilities to support accommodation

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