How to recognise a kick : A cognitive task analysis of drillers’ situation awareness during well operations

Acknowledgements This article is based on a doctoral research project of the first author which was sponsored by an international drilling rig operator. The views presented are those of the authors and should not be taken to represent the position or policy of the sponsor. The authors wish to thank the industrial supervisor and the drilling experts for their contribution and patience, as well as Aberdeen Drilling School for allowing the first author to attend one of their well control courses.Peer reviewedPostprin

Vacuum technology and space simulation

Manual on vacuum technology and space simulatio

Development of an ontology supporting failure analysis of surface safety valves used in Oil & Gas applications

Treball desenvolupat dins el marc del programa 'European Project Semester'.The project describes how to apply Root Cause Analysis (RCA) in the form of a Failure Mode Effect and Criticality Analysis (FMECA) on hydraulically actuated Surface Safety Valves (SSVs) of Xmas trees in oil and gas applications, in order to be able to predict the occurrence of failures and implement preventive measures such as Condition and Performance Monitoring (CPM) to improve the life-span of a valve and decrease maintenance downtime. In the oil and gas industry, valves account for 52% of failures in the system. If these failures happen unexpectedly it can cause a lot of problems. Downtime of the oil well quickly becomes an expensive problem, unscheduled maintenance takes a lot of extra time and the lead-time for replacement parts can be up to 6 months. This is why being able to predict these failures beforehand is something that can bring a lot of benefits to a company. To determine the best course of action to take in order to be able to predict failures, a FMECA report is created. This is an analysis where all possible failures of all components are catalogued and given a Risk Priority Number (RPN), which has three variables: severity, detectability and occurrence. Each of these is given a rating between 0 and 10 and then the variables are multiplied with each other, resulting in the RPN. The components with an RPN above an acceptable risk level are then further investigated to see how to be able to detect them beforehand and how to mitigate the risk that they pose. Applying FMECA to the SSV mean breaking the system down into its components and determining the function, dependency and possible failures. To this end, the SSV is broken up into three sub-systems: the valve, the actuator and the hydraulic system. The hydraulic system is the sub-system of the SSV responsible for containing, transporting and pressurizing of the hydraulic fluid and in turn, the actuator. It also contains all the safety features, such as pressure pilots, and a trip system in case a problem is detected in the oil line. The actuator is, as the name implies, the sub-system which opens and closes the valve. It is made up of a number of parts such as a cylinder, a piston and a spring. These parts are interconnected in a number of ways to allow the actuator to successfully perform its function. The valve is the actual part of the system which interacts with the oil line by opening and closing. Like the actuator, this sub-system is broken down into a number of parts which work together to perform its function. After breaking down and defining each subsystem on a functional level, a model was created using a functional block diagram. Each component also allows for the defining of dependencies and interactions between the different components and a failure diagram for each component. This model integrates the three sub-systems back into one, creating a complete picture of the entire system which can then be used to determine the effects of different failures in components to the rest of the system. With this model completed we created a comprehensive FMECA report and test the different possible CPM solutions to mitigate the largest risks

Design and Simulation of SmartBall for Pipeline Inspection

According to KROHNE, a 1% oil leak in a 20 inch oil pipeline can cost 450, 000 barrels and contaminate 10 m2 within 24 hours. Thus, it is compulsory to have a leak detection system in some jurisdictions. Despite there are various method of leak detection for a pipeline, yet there is no a solution that can fit all. This is due to the fact that different pipelines have different orientations and require different approaches. SmartBall, a pipeline leak detection device, utilizes acoustic for detecting leaks. It moves along the pipeline and detects a distinct leak noise. This device is different from a pig in the sense that it does not occupy the whole pipeline inner diameter and it is possible to launch it through either a pig launcher or a receive fittings. The ball was designed to accommodate sensors for data acquisition, memory card for storage and processor for data conversion. Dynamics of the SmartBall moving in a pipe that contains a flowing fluid was studied with different bends. For this analysis CFD ANSYS Fluent was used. Generally, the results show that as angle of inclination increases, the oil velocity required to propel the SmartBall increases

Design of a Novel In-Pipe Reliable Leak Detector

Leakage is the major factor for unaccounted losses in every pipe network around the world (oil, gas, or water). In most cases, the deleterious effects associated with the occurrence of leaks may present serious economical and health problems. Therefore, leaks must be quickly detected, located, and repaired. Unfortunately, most state-of-the-art leak detection systems have limited applicability, are neither reliable nor robust, while others depend on the user experience. In this paper, we present a new in-pipe leak detection system. It performs autonomous leak detection in pipes and, thus, eliminates the need for the user experience. This paper focuses on the detection module and its main characteristics. Detection in based on the presence of a pressure gradient in the neighborhood of the leak. Moreover, the proposed detector can sense leaks at any angle around the circumference of the pipe with only two sensors. We validate the concepts by building a prototype and evaluate the system’s performance under real conditions in an experimental laboratory setup.Center for Clean Water and Clean Energy at MIT and KFUPM (Project R7-DMN-08)Alexander S. Onassis Public Benefit Foundatio

Study on safety analysis of the machinery space for LNG fueled ship

본 논문은 LNG 연료추진선박의 설계에 대한 안전성을 분석하고 내연기관을 탑재한 LNG연료 추진 시스템의 안전성을 시뮬레이션을 통해 검증 하였다. 주제 1 LNG 연료추진선박의 시스템 설계에 대한 안전성 분석 LNG 연료추진선박에 대한 안정성 및 위험성 분석을 위해 전체 LNG 연료 시스템 중 발생가능한 위험요인 및 결과에 대해 시나리오를 만들고 이를 기존 디젤 연료를 사용하는 선박과 비교하여 위험도를 평가하고 문서화 하였다. 본 논문에서는 대부분의 위험요소에 대해서 검증하였으며 모든 위험요소는 인명피해가능성 (PLL, Potential Loss of Life)과 유해사고율(FAR, Fatal Accident Rate)을 기반으로 정량화 하였다. 결과적으로 LNG 연료추진선으로 인한 인명피해에 대한 위험도는 FAR 4.30이며 이는 디젤연료를 사용하는 선박에 대한 위험도인 FAR 4.16보다 0.14, 즉 약 3.4% 증가한 수치이다. 위험성 분석을 위해 LNG 연료 시스템에서 기인하는 화재 및 폭발 가능성과 충격, 충돌, 좌초, 침몰 등 간접적인 요인으로 인한 화재 및 폭발 가능성을 검토하였다. 본 연구는 선박 건조 혹은 운항 중에 선원 및 선박관리자, 신조 작업자 등 관련 작업자에게 발생가능한 위험요인을 식별하고 각각의 위험요인에 대한 권고사항을 제시한다. LNG 연료탱크 자체는 충돌로 인한 화재 및 폭발 위험성을 증가시키는 주된 요인이지만 종합적인 안전성 및 위험성 평가 결과 LNG 연료추진선박을 신조하거나 개조 시 HSE 분야의 장애요인이 되지 않는다. 본 연구는 가장 위험도가 높은 탱크 배치인 LNG 탱크가 거주구역 아래에 설치 될 경우에 대해서 운영 유지 시 발생 가능한 문제점을 위험성평가를 통해 도출하였다. 또한 관련 국제 법, 규정, 권고 사항들 사이에 존재하는 주요 차이점 및 모순에 대해서도 기술하였다. 주제 2 기관실 내 LNG 연료 시스템에 대한 안전성 분석 LNG 연료추진선은 LNG를 연료로 사용하는 내연기관의 발달과 더불어 개발되었다. 본 연구에서는 엔진에 연결된 연료공급 파이프에서 발생가능한 가스 누설을 분석하였으며, 누설된 가스의 양과 점화 시간에 따라 각각 다른 사고가 발생함을 확인하였다. 누설된 가스가 초기에 점화 될 경우에는 제트파이어(Jet Fire)가 생기나 폭발이 발생하지는 않는다. 하지만 대량의 가스가 누설된 후에 점화가 일어날 경우에는 폭발이 일어날 수 있다. 폭발 가능성은 가스의 농도와 양에 영향을 받는다. 본 연구에서는 기관실 내 고압 이중관이 파열 될 경우 발생할 수 있는 화재 및 폭발 하중을 시뮬레이션을 통해 분석하였으며, 다음과 같은 사항을 고려하였다. 기하학 모델링. 가스 누설이 발생할 공간은 FLACS V10을 통해 실제와 유사하게 모델링 하였으며, 통풍, 기체 확산, 화재 및 폭발에 대한 시뮬레이션을 실시하였다. 통풍 및 기체 확산에 대한 시뮬레이션.(일시 적인 가스 누설의 경우) 설계 공간 및 통풍 용량 등에 대한 기본 조건을 바탕으로 하여 발생가능한 최악의 가스 누설양을 분석하고 두개의 다른 시나리오를 적용하여 시뮬레이션을 시행하였다. 설계 공간 내의 통풍양은 누설 발생 시작 조건을 기반으로 시뮬레이션 하였다. 폭발 시뮬레이션. FLACS를 사용하여 폭발에 대한 시물레이션을 하였으며 기관실 내벽에 작용하는 폭발 압력을 도출하였다. 이를 위해 가스의 누설양과 위치, 점화원의 위치를 바꾸어 총 6번의 시뮬레이션을 시행하였다. 화재 시뮬레이션. 화재 시뮬레이션은 가스 누설 초기에 점화가 되었을 경우를 가정하고 제트파이어를 FLACS에서 설계한 모델을 기반으로 KAMELEON FIREEX(KFX)로 전환하여 시뮬레이션 하였다. 화재 시 구조물의 복사유량을 감안하였으며, 누설양에 따라 세가지의 시뮬레이션을 진행하였다. 화재는 정적 상태에서 화재가 발생할 경우를 가정하였으며, 최악의 경우에 대해서는 제트파이어의 방향을 달리하여 시뮬레이션 하였다. 분석 시뮬레이션을 통해 도출한 폭발 및 화재 하중은 유사한 구조의 기존 디젤을 연료를 사용하는 선박과 비교 하여 제시하였다. 본 분석은 정성적인 평가이며 구조강도에 대한 계산은 포함하지 않았다. 만약 하중이 일반적으로 허용가능한 하중을 초과하는 경우, 추가적인 구조 강도에 대한 시뮬레이션이 필요할 것이며 이를 대응하기 위한 권고사항이 제시되어야 한다. 전형적인 대응책은 검증된 가스 누설 감지 시스템 설치, 가스 누설 부위에 살수, 혹은 중요 구조물 및 배관에 PFP(Passive Fire Protection)적용, 가스 감지 시 연료관 자동 블로우오프(Blow-Off), 통풍 시스템 용량 조절, 발생가능한 점화원 최소화 등이 있다. 본 연구는 또한 누설에 대한 발생 빈도 평가 및 이중관의 전체 파열에 대한 계산을 포함하고 있으며 엔진과 ESD밸브(Emergency Shut-down Valve) 사이의 거리와 밸브가 닫히는 시간의 영향 또한 고려하였다.|The abstract has been divided in two parts (1 and 2) as follows: Part 1. Safety analysis and design concept of LNG fueled ship The safety and Risk analyses of LNG fueled ship and system carried out, focusing in particular an analysis of the causes and consequences of hazards scenarios for entire LNG fuel system and with objective to evaluate and document the risk level of the design of the vessel compared to a diesel fueled container vessel of equal type. All major hazards have been considered and the risk is quantified in terms of Potential Loss of Lives (PLL) and Fatal Accident Rate (FAR). In total, the personnel risk for the vessel has been estimated to a FAR of 4.30. A similar new conventional diesel fueled vessel will have an estimated personnel risk level of a FAR of 4.16. The net increase of FAR 0.14 corresponds to an increase in risk by 3.4 % compared to the diesel fueled container vessel. The main categories of hazard scenarios are: Fire and explosion initiated from the LNG system, fire and explosion not LNG initiated, dropped objects, collisions, grounding, foundering and occupational accidents. The purpose of the analysis is to identify safety hazards that may represent risks to crew and third parties such as maintenance personnel, yard workers and other ships during operation. The risks and hazards identified following proposed recommendations with comprehensive summary in term of design and operation. The main result from the safety analysis and HAZID showed that the estimated HAZID increase is mainly due to the presence of the LNG tank and its effect on the risk from fire/explosions due to ship collision. The HAZID results confirm that there is no major HSE showstoppers to carry out construction and conversion on vessel using dual fueled. The main selection criterion was the potential design, worst case scenario for location of LNG tank below accommodation, technical and operational capabilities in conducting such HAZID study and investigations. Several important gaps in mandatory regulations, standards, guidelines or of relevant organizations beyond mandatory regulations have been identified and addressed. Part 2. Safety analysis of LNG fuel for machinery space A LNG gas fuel ship is being developed where LNG gas is used as fuel in internal combustion engines (modified diesels). In this concept to investigate possible consequences of a gas leak in the feeding pipe to the engines. Depending on the size of the leak and the time of ignition, different developments of the accident can occur. Two main developments are foreseen; early ignition and late ignition. If the gas is ignited early, there will be a jet fire and no explosion. If the gas is ignited after most of the gas is released, there may be an explosion. The possibility for a strong explosion is dependent of the gas concentration and size of the gas cloud. The main objective is to find the fire and explosion loads caused by a "rupture of high pressure double wall pipe in machinery space". My safety simulations, modelling and analysis includes the following activities: • Geometry modelling. the entire room is modelled with most details in the area where the leak will start. The geometry is modelled in FLACS v10 so that the geometry model can be applied for ventilation, dispersion, fire and explosion simulations. • Ventilation and dispersion simulations. The leak is modelled as a transient leak. The worst case leak size is estimated based on knowledge of the size of the room, ventilation conditions, etc. Two different leak rates in two different leak scenarios are performed. The ventilation in the room is simulated and used as start conditions when the leak starts. • Explosion simulations. Explosions are simulated in FLACS and explosion pressures on engine room walls are obtained. Total of six simulations are performed with different cloud size, locations and two ignition locations. • Fire simulations. The leak is modelled as a jet fire assuming it is ignited from the start of the leak. The jet fire is simulated in KAMELEON FIREEX (KFX). Radiation flux on the structure is obtained during the fire. three simulations with different constant leak rates are performed. The extent of the fire when a steady state situation is established is presented. One worst case jet direction is performed based on other fire simulations. Note that the geometry model from FLACS will be converted to KFX. • Analysis. The obtained explosion and fire loads are compared with typical collapse loads for similar structures. This evaluation is qualitative, and does not include rigorous calculation of structure strength. If the loads are above typical acceptable loads, simulations of the structure strength will be suggested. Possible mitigating measures will also be recommended. Typical mitigating measures are a good gas detection system, start of deluge on gas detection (this may reduce possible explosion pressures), Passive fire Protection (PFP) on critical structure and piping, automatic blow down of fuel pipe system on gas detection, improved air ventilation, reduced ignition sources, etc. The scope is extended to consider frequency assessment, and full bore rupture calculation. The effect of a smaller ESD segment and shorter ESD closure time are also consideredContents i List of Figures v List of Tables x Abstract xiii Abstract (초록) xvi Chapter 1 Safety analysis and design of LNG fueled ship 1 1.1 General risk terms 1 1.2 Vessel design concept 2 1.3 Safety analysis results 7 Chapter 2 The Hazard Identification (HAZID) of LNG dual Fueled Ship 11 2.1 Introduction 11 2.2 Analysis basis and methodology 12 2.3 Findings and results 14 2.4 Recommendations 25 2.5 Conclusions 32 Chapter 3 Fire and explosion for LNG fueled ship 34 3.1 Introduction 34 3.2 Modelling principles 34 3.3 Fire and explosion due to leak in LNG fuel system 35 3.3.1 Initial events – LNG leaks 36 3.3.2 Leak size 38 3.3.3 Frequency assessment 38 3.3.4 Consequence assessment 41 3.3.5 Leaks during bunkering (initial event 1-2) 43 3.3.5.1 Small leaks 45 3.3.5.2 Large leaks 49 3.3.5.3 Personnel risk 53 3.3.6 Internal ignition - within the space of the leak source (initial event 3, 4, 5 and 7) 54 3.3.7 External ignition - leak vented and ignited (initial event 4-8) 57 3.3.8 Risk summary – Leak in LNG fuel system 59 3.4 Fire and explosion in other areas- not LNG initiated 60 3.4.1 Fire/explosion in machinery spaces/engine room 62 3.4.1.1 Not LNG initiated 62 3.4.1.2 Escalation to the LNG fuel system 62 3.4.2 Fire/explosion in cargo area and accommodation 63 3.4.2.1 Not LNG initiated 63 3.4.2.2 Escalation to the LNG fuel system 64 3.4.3 Fire/explosion in diesel fuel tanks besides the LNG fuel Tank 65 3.4.4 Risk summary – Fire/explosion not LNG initiated 65 3.5 Findings and results 67 3.6 Conclusions 70 Chapter 4 Safety simulations, modelling and analysis of LNG dual fuel in machinery space for internal gas combustion engines 71 4.1 Introduction 71 4.1.1 Objective 71 4.1.2 Scope 71 4.2 Basis for analysis 73 4.2.1 Approach 73 4.2.2 Geometry 74 4.3 Leak scenarios 78 4.4 Engine room ventilation 81 4.5 Dispersion analysis 83 4.6 Explosion Analysis 87 4.6.1 Vapour cloud explosion simulations 87 4.6.2 Pressure impact on humans 92 4.6.3 Summary of explosion analysis 92 4.7 Fire analysis 94 4.7.1 Jet fire simulations 94 4.7.2 Summary of fire analysis 103 4.8 Frequency assessment 106 4.8.1 Leak frequency 106 4.8.2 Ignition probability 110 4.8.3 Detection and isolation of fuel leaks from dual pipeline 111 4.8.3.1 Detection failure 111 4.8.3.2 Isolation failure 112 4.8.4 Summary of frequency assessment 114 4.9. Findings and results 114 4.9.1 Explosions 115 4.9.2 Fires 116 4.10 Conclusions 118 Chapter 5 Conclusions 120 Reference 122 Lists of Publications and Lecturing 128Docto

Reliable Sensing of Leaks in Pipelines

Leakage is the major factor for unaccounted losses in every pipe network around the world (oil, gas or water). In most cases the deleterious effects associated with the occurrence of leaks may present serious economical and health problems. Therefore, leaks must be quickly detected, located and repaired. Unfortunately, most state of the art leak detection systems have limited applicability, are neither reliable nor robust, while others depend on user experience. In this work we present a new in-pipe leak detection system, PipeGuard. PipeGuard performs autonomous leak detection in pipes and, thus, eliminates the need for user experience. This paper focuses on the detection module and its main characteristics. Detection in based on the presence of a pressure gradient in the neighborhood of the leak. Moreover, the proposed detector can sense leaks at any angle around the circumference of the pipe with only two sensors. We have validated the concepts by building a prototype and evaluated its performance under real conditions in an experimental laboratory setup.Alexander S. Onassis Public Benefit Foundatio

Frequency domain analysis for detecting pipeline leaks

The original publication can be found at http://scitation.aip.org/hyoThis paper introduces leak detection methods that involve the injection of a fluid transient into the pipeline, with the resultant transient trace analyzed in the frequency domain. Two methods of leak detection using the frequency response of the pipeline are proposed. The inverse resonance method involves matching the modeled frequency responses to those observed to determine the leak parameters. The peak-sequencing method determines the region in which the leak is located by comparing the relative sizes between peaks in the frequency response diagram. It was found that a unique pattern was induced on the peaks of the frequency response for each specific location of the leak within the pipeline. The leak location can be determined by matching the observed pattern to patterns generated numerically within a lookup table. The procedure for extracting the linear frequency response diagram, including the optimum measurement position, the effect of unsteady friction, and the way in which the technique can be extended into pipeline networks, are also discussed within the paper.Pedro J. Lee, John P. Vítkovský, Martin F. Lambert, Angus R. Simpson and James A. Ligget