Operation failure of risk analysis on floating storage and offloading

The need for petroleum in daily life is increasing. The oil comes from the seabed, so it is necessary to have adequate facilities during the exploration and exploitation of crude oil. The process of distributing crude oil to FSO is assisted by the Product Transfer System pipeline. In this process there is a possibility of failure that occurs form several factors, namely tools, weather and sea conditions, and human. In this study, the analysis of the risk of operational failure during loading-unloading of crude oil is discussed. The analysis was carried out using the HAZOP Analysis and Bow-Tie Analysis methods. HAZOP Analysis for hazard identification, and Bow-Tie Analysis for finding the appropriate mitigation. From this method, an overview of the risks than can occur can be obtained so that the risk control required by FSO can be implemented. From the results of this study, it was found that there are 41 potential hazards on the process of loading-unloading crude oil FSO, with the highest risk is inadequate quality of the transfer equipment components with the likelihood rank is 4 and severity rank is 4. The results of Bow-Tie visualization of dominant risk found five causes, namely corrosion, inadequate material quality, eroded material, service life, and material degradation, and five consequences, namely property damage, delayed operational activities, oil spills, environmental damage due to oil spill, and corrosion occurs on the product transfer equipment.


Introduction
In daily life, the need for petroleum has many benefits in various fields, such as household needs, construction, vehicle fuel, and others.This makes the need for oil very profitable.Petroleum is a strategic natural resource, has high economic value, and is a non-renewable natural resource.Petroleum is found under land and the seabed.So, in the process of exploration and exploitation of oil off the coast, of course, it is necessary to have adequate facilities for the extraction process.Of course, the facilities needed are those that can survive the harsh marine environment.There are many types of offshore structures, this paper will discuss about Floating Storage and Offloading (FSO).Floating Storage and Offloading (FSO) is one of the most profitable structures in the petroleum industry [1].FSO itself is a floating offshore platform designed for offshore hydrocarbon exploration activities, one of which is crude oil.FSO has several functions, which include loading-unloading crude oil.Loadingunloading is an activity where the FSO receives the processed oil, stores it, and distributes it to a carrier or shuttle tanker.While offshore, the FSO is moored with a floating structure, namely Single Point Mooring (SPM), so that its balance is not disturbed due to environmental loads during the loading-unloading process of crude oil [2].Due to its large size, the FSO significantly influences wave, wind, and current loads.SPM is connected to the product transfer system pipe, which transfers products from the seabed to the ship.At this time, the author conducted research on Y Floating Storage and Offloading System (FSO).
In distributing oil to FSO, it is undeniable that there are possibilities of failure.Operational failure during loading-unloading of crude oil can result in losses from small to large scale for several parties involved.Failure, in this case, can occur from 2 factors, namely internal and external factors, both from tools and weather and sea conditions.This can be detrimental to many parties and also harms many aspects, such as the environment, people, assets and companies, and others.
Failure can occur anytime and anywhere, so within the company, it is necessary to carry out risk management to avoid or minimize the occurrence of the risk.Risk management needs to be managed qualitatively and quantitatively to predict or control risks in a project [3].Thus, risk management can make it easier for companies to determine the actions taken when these risks occur.The objectives of this paper is to determine the most potential hazard failure of loading-unloading crude oil operation of FSO and also their threats and consequences using HAZOP and Bow Tie Analysis.
There are several cases regarding failures in offshore structures, which then cause several major impacts, be it on reputation, assets, environmental pollution, or fatalities in the form of fatalities [4].Cases that have occurred are like the Oil Rig owned by Transocean, which exploded, caught fire, and sank and then caused environmental pollution due to oil leaks and also fatality in the form of fatalities of as many as 11 workers [5].This results from missed warning signals and failures in monitoring and disseminating information.Another case is the FPSO Cidade do Rio de Janeiro, which experienced an oil leak due to a cracked hull on the FPSO [6].There have been several risk analyses regarding FPSOs and other offshore structures.The author carried out research at North West Java East, especially research on operation failures on loading-unloading crude oil at the FSO.Thus, early prevention can be done for each potential hazard and appropriate mitigation if the hazard occurs.

Literature review
Table 1.Literature review summary References Scope/Topics Methods Objectives [7] Drilling platform BOW TIE to represent the potential accident scenarios, their causes, and the associated consequences [8] Anchor Handling Operation BOW TIE to reduce potential risks during AHO operations and increase maritime safety. [9]

Port Berth Construction Hazard Identification
To identify the hazards and risks associated with the construction of a dock at Visakhapatnam Port and to evaluate existing preventive controls to avoid incidents and accidents.
[10] Board Ships BOW TIE to conduct a risk analysis for confined space accidents on board ships using fuzzy bow-tie methodology.And to identify the hazards and risks associated with confined spaces on board ships and to evaluate the effectiveness of existing preventive controls to avoid accidents and incidents [11] Small LNG-Fueled Fishing Ship

Hazard Identification
To conduct a preliminary risk assessment on the development of the fuel gas supply system of a small LNG-fueled fishing ship.To identify potential hazards and risks associated with the decommissioning process and to evaluate the effectiveness of existing preventive controls to avoid accidents and incidents.
[14] Ship Grounding Accident Hazard Identification to identify the hazard of ship grounding; where a ship runs on a rock with a forward speed, and to select a set of credible scenarios with a limited number that can still represent all possible situations of the accidents [15] Mobile Mooring System HAZOP to explain the potential causes and the possible consequences of mooring system failures using HAZOP as preliminary analysis

Failure risk
In this research, the case study used in Northwest Java, one of the floating offshore platforms in Indonesia.Table 2 shows the likelihood ranking used in this paper.The severity rank is on a scale of 1 to 6, divided into four aspects: health and safety, environmental, equipment damage and business value, and business reputation as shown in Table 3

Major impact on business reputation internationally
So, from the questionnaire results, it can be calculated for the likelihood and severity rank of each potential hazard.Each variable has different likelihood and severity category values, so the likelihood and severity ranking is calculated using the formula below: Description:   = rating constant (1 until 5 for likelihood, and 1 until 6 for severity)   = respondent probability I = 0,1,2,3,4,… n N = total numbers of respondent

4.Risk matrix
From the calculation results of the average likelihood rank and severity rank, the next step is to classify the level of risk.The risk matrix used follows ISO 31000:2009 [16], divided into three levels : low risk, medium risk, and high risk.To determine the level of the risk matrix, the likelihood ranking, and severity ranking is multiplied for each potential hazard.From the multiplication results, it can be determined the level of risk for each potential hazard variable.
After assessing the causes and impacts of each existing risk is carried out, the determination of risk control or what can be called operational controls is carried out.Determination of risk control is an action to reduce or prevent the risk that has been predicted in advance.Risk control is carried out by distributing questionnaires back to stakeholders.Next step can be continued by calculating the likelihood and severity again on operational controls.This calculation is carried out again to know whether the controls that have been made are effective enough to minimize the impact of the potential (1) hazards that exist.From the questionnaires that have been distributed, the likelihood and severity results are obtained from the five respondents for operational controls for each potential hazard.The risk level classification table can be seen below in the Risk Matrix table 4. L Low Risk -Acceptable risk additional controls are not required.The value of this low risk is from 1 to 4. The likelihood and severity rank can be calculated from the questionnaire results above.In the same way, as in the previous likelihood and severity calculations, the likelihood and severity ranking results are obtained using operational controls.

Risk matrix after operational controls
From the likelihood and severity ranking results above, the risk matrix can then be calculated again with the presence of operational controls.The calculation of the risk matrix is carried out the same as before, namely the multiplication between the likelihood ranking and the severity ranking.Thus, the results of the risk matrix are obtained as shown in the following table : From the calculation of the risk matrix, it is found that the operational controls for each potential hazard are categorized in green, which is low risk.Thus, it can be concluded that the operational controls that have been made are efficient enough to be used to reduce the impact of the potential hazards that exist in the loading-unloading process of crude oil at the Y FSO.

HAZOP worksheet
Furthermore, the analysis results above can be entered into the HAZOP Worksheet table.HAZOP Worksheets are columns containing main activities, tasks, activity codes, activity descriptions, potential hazards, possible causes, possible impacts, ranking for likelihood and severity for each potential hazard, operational controls, and ranking for likelihood and severity for each operational control.Thus, a HAZOP Worksheet was formed on the crude oil transfer operation at FSO Y, as shown in the table 5 below.

Bow-tie analysis
Bow-Tie Analysis can be continued after calculating the likelihood, severity, and risk matrix, which is then summarized in a HAZOP Worksheet table.Based on the HAZOP Analysis above, the critical risk during the loading-unloading process of crude oil at the Y FSO occurs in the floating and subsea hose operations during offloading of crude oil from the Y FSO to the Tanker, with the potential danger being that the quality of the transfer equipment components is inadequate.Risk analysis using the Bow-Tie Analysis method was performed using BowtieXP software.This method can then clearly describe the threats and consequences.In this Bow-Tie diagram, you can find the causal and preventive variables on the left side of the diagram, the consequences and mitigation variables on the right side of the diagram, the escalation factor, and the mitigation escalation.The following is Bow-Tie Analysis Modelling for activity code inadequate quality of transfer equipment components.

Figure 1 .
Figure 1.Bow-Tie Analysis Modeling for Indequate Quality of the Transfer Equipment Components

Table 4 .
Risk Matrix Likelihood Action is needed to reduce the risk, but the cost of necessary prevention must be carefully calculated and limited.The value of this moderate risk is from 5 to 12.

Table 5 .
HAZOP Worksheet ResultTask 1: Floating and subsea hose loading crude oil from Platform to FSO

Table 6 .Table 6 .
The description of the threat of inadequate quality of the transfer equipment components is shown in Threat of Inadequate Quality of The Transfer EquipmentThe description of the consequences of inadequate quality of the transfer equipment components is shown in Table7.

Table 7 .
Consequences of Inadequate Quality of The Transfer Equipment