Quantitative Risk Assessment (QRA) of an Exploratory Drilling Oil Spill in Deepwater Gulf of Mexico

2014 ◽  
Author(s):  
Muhammad Zulqarnain ◽  
Mayank Tyagi
Keyword(s):  
Risk Assessment ◽  
Gulf Of Mexico ◽  
Drill Pipe ◽  
Quantitative Risk Assessment ◽  
Reservoir Properties ◽  
Worst Case ◽  
Equipment Reliability ◽  
Discharge Rates ◽  
First Case ◽  
Technological Improvements

Major offshore accidents such as Macondo well incident highlight one of the possible failure modes and subsequent disasters when an offshore engineering project could go wrong. Such events can potentially happen during any phase of an offshore well’s life — starting from the exploratory drilling phase to the final phase of plug and abandonment. Major factors that significantly contribute in defining such accident scenarios are the geological and operational complexities, equipment reliability, human factors, geographical/economy location, and environmental conditions. The path taken by the reservoir fluids to reach the sea floor is also an important factor in determining the worst case discharge rates. It is expected that the environmental risks from an oil/gas spill would also be function of the type of hydrocarbons released and duration of the spill. A representative Neogene well is studied for quantitative risk assessment (QRA) for spill in exploratory phase from the Mississippi Canyon in the Gulf of Mexico with a water depth of 3,000ft and total vertical depth of 16,726 ft and the representative reservoir properties for this area are selected from the literature. Due to the large variation of reservoir properties, lognormal distributions have been assumed for some of the reservoir properties and from the Monte Carlo simulations P10, P50 and P90 values are estimated. Based on P50 and P90 values, the worst case discharge rates are calculated using a commercially available multiphase flow simulator with black oil model. Based on historical trends, release of hydrocarbons during blowouts are simulated for the following circumstances: seabed and topside releases, restricted and unrestricted flow through BOP, flow with drill pipe inside the wellbore and open hole flow without drill pipe and flow from the reservoir when it is either fully or partially penetrated. To incorporate the technological improvements and study their effects on the reduction of the overall risk associated with deepwater drilling activity, two cases are considered and compared to each other. First case is based on the historical data and the second case is a modified version of the first case by incorporating some of the recent technological improvements and newly built oil spill response systems e.g. capping stacks. The historical kick statistics and the equipment reliability data available in the literature is used to analyze various scenarios and corresponding flow rates. Risk is analyzed using the failure probability and consequence analysis and is presented in the form of a risk matrix for the different case studied and for the overall drilling activity as well.

Quantification of Risks Associated With a Representative Production Well in the Gulf of Mexico

2015 ◽  
Author(s):  
Muhammad Zulqarnain ◽  
Mayank Tyagi
Keyword(s):  
Risk Assessment ◽  
Monte Carlo ◽  
Gulf Of Mexico ◽  
Fault Tree ◽  
Quantitative Risk Assessment ◽  
Delayed Response ◽  
Production Well ◽  
Reservoir Properties ◽  
Worst Case ◽  
Sand Control

After Macondo incident a great effort is under way to improve the safety of deepwater drilling and production operations and enhance the capabilities of different well barrier to stop the oil spill on its earliest stages. This study is a part of that collective effort to make offshore operations safe and decrease the associated risks. The main objective of this study is to quantify and categorize the risk associated with a representative well in the Gulf of Mexico during its normal production operations. In order to achieve an appropriate balance between safety and economics of deepwater oil and gas operations, Quantitative Risk Assessment (QRA) techniques can be successfully used. Quantified risk is computed from the product of blowout frequency and volume of oil spilled as a consequence. Blowout frequency is calculated from Fault Tree Analysis (FTA) and spilled oil volume is estimated from simulating multiphase fluid flow and heat transfer in wellbores. A large number wells are completed with some sort of bottom hole sand control elements to prevent production of sand. The failure of these control elements may have severe consequence and in some cases may result in uncontrolled hydrocarbon flow to the environment as well. A representative production well from the Mississippi Canyon in the Gulf of Mexico is selected for the for quantitative risk assessment (QRA) analysis. The well is completed with cased hole gravel pack and with sand control elements in place. The representative reservoir properties for this well are selected from the literature and uncertainties in properties are accounted for by fitting lognormal distribution and carrying out Monte Carlo simulations. P50 value for the reservoir properties from Monte Carlo simulation is used to find worst case discharge rates by using a commercially available multiphase flow simulator with black oil model. A Fault Tree is constructed to find the blowout probability based on the equipment failure data. From the minimal cut set method the importance and sensitivity of different well barrier is analyzed and most important areas to focus on are identified. The analysis showed that the constructed fault tree is most sensitive to sand screen failures, followed by subsea production tree and delayed response to a situation of immediate concern.

Risk assessment of Campylobacter species in shellfish: identifying the unknown

1997 ◽  
Vol 35 (11-12) ◽  
pp. 29-34 ◽  
Author(s):  
P. Teunis ◽  
A. Havelaar ◽  
J. Vliegenthart ◽  
G. Roessink
Keyword(s):  
Risk Assessment ◽  
Quantitative Risk Assessment ◽  
Contamination Level ◽  
Risk Of Infection ◽  
Worst Case ◽  
Considerable Uncertainty ◽  
Risk Estimates ◽  
Consumption Data ◽  
Campylobacter Infection ◽  
Campylobacter Spp

Shellfish are frequently contaminated by Campylobacter spp, presumably originating from faeces from gulls feeding in the growing or relaying waters. The possible health effects of eating contaminated shellfish were estimated by quantitative risk assessment. A paucity of data was encountered necessitating many assumptions to complete the risk estimate. The level of Campylobacter spp in shellfish meat was calculated on the basis of a five-tube, single dilution MPN and was strongly season-dependent. The contamination level of mussels (<1/g) appeared to be higher than in oysters. The usual steaming process of mussels was found to completely inactivate Campylobacter spp so that risks are restricted to raw/undercooked shellfish. Consumption data were estimated on the basis of the usual size of a portion of raw shellfish and the weight of meat/individual animal. Using these data, season-dependent dose-distributions could be estimated. The dominant species in Dutch shellfish is C. lari but little is known on its infectivity for man. As a worst case assumption, it was assumed that the infectivity was similar to C. jejuni. A published dose-response model for Campylobacter-infection of volunteers is available but with considerable uncertainty in the low dose region. Using Monte Carlo simulation, risk estimates were constructed. The consumption of a single portion of raw shellfish resulted in a risk of infection of 5–20% for mussels (depending on season; 95% CI 0.01–60%). Repeated (e.g. monthly) exposures throughout a year resulted in an infection risk of 60% (95% CI 7–99%). Risks for oysters were slightly lower than for mussels. It can be concluded that, under the assumptions made, the risk of infection with Campylobacter spp by eating of raw shellfish is substantial. Quantitative risk estimates are highly demanding for the availability and quality of experimental data, and many research needs were identified.

Development and Implementation of a Liquid Pipeline Quantitative Risk Assessment Model

2014 ◽  
Author(s):  
Jerico Perez ◽  
David Weir ◽  
Caroline Seguin ◽  
Refaul Ferdous
Keyword(s):  
Risk Assessment ◽  
Risk Reduction ◽  
Assessment Tool ◽  
Assessment Model ◽  
Quantitative Risk Assessment ◽  
Pipeline System ◽  
Risk Assessment Model ◽  
Worst Case ◽  
Risk Appetite ◽  
Assessment Results

To the end of 2012, Enbridge Pipelines employed an in-house developed indexed or relative risk assessment algorithm to model its liquid pipeline system. Using this model, Enbridge was able to identify risk control or treatment projects (e.g. valve placement) that could mitigate identified high risk areas. A changing understanding of the threats faced by a liquid pipeline system and their consequences meant that the model changed year over year making it difficult to demonstrate risk reduction accomplished on an annual basis using a relative scoring system. As the development of risk management evolved within the company, the expectations on the model also evolved and significantly increased. For example, questions were being asked such as “what risk is acceptable and what risk is not acceptable?”, “what is the true risk of failure for a given pipe section that considers the likelihood of all threats applicable to the pipeline”, and “is enough being done to reduce these risks to acceptable levels?” To this end, starting in 2012 and continuing through to the end of 2013, Enbridge Pipelines developed a quantitative mainline risk assessment model. This tool quantifies both threat likelihood and consequence and offers advantages over the indexed risk assessment model in the following areas: • Models likely worst case (P90) rupture scenarios • Enables independent evaluation of threats and consequences in order to understand the drivers • Produces risk assessment results in uniform units for all consequence criteria and in terms of frequencies of failure for likelihood • Aggregates likelihood and consequence at varying levels of granularity • Uses the risk appetite of the organization and its quantification allows for the setting of defined high, medium, and low risk targets • Quantifies the amount of risk in dollars/year facilitating cost-benefit analyses of mitigation efforts and risk reduction activities • Grounds risk assessment results on changes in product volume-out and receptor sensitivity • Balances between complexity and utility by using enough information and data granularity to capture all factors that have a meaningful impact on risk Development and implementation of the quantitative mainline risk assessment tool has had a number of challenges and hurdles. This paper provides an overview of the approach used by Enbridge to develop its quantitative mainline risk assessment model and examines the challenges, learnings and successes that have been achieved in its implementation.

scholarly journals Domain-specific risk assessment using integrated simulation: A case study of an onshore wind project

2021 ◽  
Author(s):  
Emad Mohamed ◽  
Nima Gerami Seresht ◽  
Stephen Hague ◽  
Adam Chehouri ◽  
Simaan M. AbouRizk
Keyword(s):  
Risk Assessment ◽  
Wind Farm ◽  
Critical Path ◽  
Quantitative Risk Assessment ◽  
Integrated Simulation ◽  
Domain Specific ◽  
Risk Assessment Models ◽  
First Case ◽  
Assessment Approach

Although many quantitative risk assessment models have been proposed in literature, their use in construction practice remain limited due to a lack of domain-specific models, tools, and application examples. This is especially true in wind farm construction, where the state-of-the-art integrated Monte Carlo simulation and critical path method (MCS-CPM) risk assessment approach has yet to be demonstrated. The present case study is the first reported application of the MCS-CPM method for risk assessment in wind farm construction and is the first case study to consider correlations between cost and schedule impacts of risk factors using copulas. MCS-CPM provided reasonable risk assessment results for a wind farm project, and its use in practice is recommended. Aimed at facilitating the practical application of quantitative risk assessment methods, this case study provides a much-needed analytical generalization of MCS-CPM, offering application examples, discussion of expected results, and recommendations to wind farm construction practitioners.

Quantitative Risk Assessment for Human Salmonellosis through the Consumption of Pork Sausage in Porto Alegre, Brazil

2011 ◽  
Vol 74 (4) ◽  
pp. 553-558 ◽  
Author(s):  
LISANDRA MÜRMANN ◽  
LUIS GUSTAVO CORBELLINI ◽  
ALEXANDRE ÁVILA COLLOR ◽  
MARISA CARDOSO
Keyword(s):  
Risk Assessment ◽  
Cooking Time ◽  
Quantitative Risk Assessment ◽  
Average Risk ◽  
Porto Alegre ◽  
Case Scenario ◽  
Worst Case ◽  
Pork Sausage ◽  
The People ◽  
Pork Sausages

A quantitative microbiology risk assessment was conducted to evaluate the risk of Salmonella infection to consumers of fresh pork sausages prepared at barbecues in Porto Alegre, Brazil. For the analysis, a prevalence of 24.4% positive pork sausages with a level of contamination between 0.03 and 460 CFU g−1 was assumed. Data related to frequency and habits of consumption were obtained by a questionnaire survey given to 424 people. A second-order Monte Carlo simulation separating the uncertain parameter of cooking time from the variable parameters was run. Of the people interviewed, 87.5% consumed pork sausage, and 85.4% ate it at barbecues. The average risk of salmonellosis per barbecue at a minimum cooking time of 15.6 min (worst-case scenario) was 6.24 × 10−4, and the risk assessed per month was 1.61 × 10−3. Cooking for 19 min would fully inactivate Salmonella in 99.9% of the cases. At this cooking time, the sausage reached a mean internal temperature of 75.7°C. The results of the quantitative microbiology risk assessment revealed that the consumption of fresh pork sausage is safe when cooking time is approximately 19 min, whereas undercooked pork sausage may represent a nonnegligible health risk for consumers.

scholarly journals Risk Assessment of the Large-Scale Hydrogen Storage in Salt Caverns

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2856
Author(s):  
Maria Portarapillo ◽  
Almerinda Di Benedetto
Keyword(s):  
Risk Assessment ◽  
Hydrogen Storage ◽  
Large Scale ◽  
High Energy ◽  
Quantitative Risk Assessment ◽  
Case Scenario ◽  
Worst Case ◽  
Low Leakage ◽  
Riser Pipe ◽  
Salt Caverns

Salt caverns are accepted as an ideal solution for high-pressure hydrogen storage. As well as considering the numerous benefits of the realization of underground hydrogen storage (UHS), such as high energy densities, low leakage rates and big storage volumes, risk analysis of UHS is a required step for assessing the suitability of this technology. In this work, a preliminary quantitative risk assessment (QRA) was performed by starting from the worst-case scenario: rupture at the ground of the riser pipe from the salt cavern to the ground. The influence of hydrogen contamination by bacterial metabolism was studied, considering the composition of the gas contained in the salt caverns as time variable. A bow-tie analysis was used to highlight all the possible causes (basic events) as well as the outcomes (jet fire, unconfined vapor cloud explosion (UVCE), toxic chemical release), and then, consequence and risk analyses were performed. The results showed that a UVCE is the most frequent outcome, but its effect zone decreases with time due to the hydrogen contamination and the higher contents of methane and hydrogen sulfide.

An Investigation into VOC Emissions from Polyurethane Flexible Foam Mattresses

2003 ◽  
Vol 22 (4) ◽  
pp. 237-259 ◽  
Author(s):  
K. Hillier ◽  
T. Schupp ◽  
I. Carney
Keyword(s):  
Risk Assessment ◽  
Human Health ◽  
Large Scale ◽  
Analytical Data ◽  
Human Health Risk ◽  
Quantitative Risk Assessment ◽  
Exposure Model ◽  
Product Knowledge ◽  
Trace Impurities ◽  
Worst Case

Emissions of volatile species from flexible polyurethane foam mattresses were investigated by using large scale chamber tests designed to replicate the product use as mattress cores. Various trace impurities were identified and their concentrations were measured for input into a human health and toxicity risk assessment, which has concluded that none was injurious to health. The raw materials used to make the foam were analysed to identify the source of emanations and routes to their reduction or elimination. Several analytical artefacts were identified, and some recommendations made for their avoidance. Detailed product knowledge was essential to the reliable interpretation of analytical data. A quantitative risk assessment was carried out on each of the volatiles. No evidence of any human health risk was identified from the ‘worst-case’ exposure model employed

scholarly journals Banked Human Milk and Quantitative Risk Assessment ofBacillus cereusInfection in Premature Infants: A Simulation Study

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Antoine Lewin ◽  
Gilles Delage ◽  
France Bernier ◽  
Marc Germain
Keyword(s):  
Risk Assessment ◽  
Human Milk ◽  
Bacillus Cereus ◽  
Premature Infants ◽  
Scientific Evidence ◽  
Causal Link ◽  
Quantitative Risk Assessment ◽  
Worst Case ◽  
Potential Health ◽  
Infectious Risk

Background. Banked human milk (BHM) offers potential health benefits to premature babies. BHM is pasteurized to mitigate infectious risks, but pasteurization is ineffective against sporulating bacteria such asBacillus cereus. Sepsis related toBacillus cereusin premature infants is severe and can often be fatal. Even if a causal link has never been established, BHM has been suggested as a potential source of infection in premature infants.Objective. Our aim was to estimate the potential risk ofBacillus cereusinfection in preterm infants caused by the ingestion of contaminated pasteurized BHM using different post-pasteurization release criteria (i.e., 9 sampling of 100 microliters versus the HMBANA guideline of 1 sampling of 100 microliters per pool).Methods. In the absence of scientific evidence regarding the risk ofBacillus cereusinfection by the ingestion of BHM in premature infants, risk assessment using Monte Carlo simulation with the exponential dose-response model was performed. Three scenarios of infectious risk (annual incidence rate of 0.01%, 0.13%, and 0.2%) with 18 variations of theB. cereusvirulent dose (from 0.5 CFU/ml to 200 CFU/ml) were simulated.Results. The mean risk differential between the two methods of post-pasteurization bacteriological control for realistic infectious doses of 30 to 200 CFU/ml ranges from 0.036 to 0.0054, 0.47 to 0.070, and 0.72 to 0.11 per million servings, for each of the three scenarios.Conclusion. Simulation highlights the very small risk ofBacillus cereusinfection following the ingestion of pasteurized BHM, even in the worst case scenarios, and suggests that a 100-microliter sample for post-pasteurization culture is sufficient.

scholarly journals Safety Management Plan through Offsite Risk Assessment during Tank Terminal Construction

2020 ◽  
Vol 42 (11) ◽  
pp. 548-557
Author(s):  
Eun Sung Baek ◽  
Kyoshik Park
Keyword(s):  
Risk Assessment ◽  
Safety Management ◽  
Quantitative Risk Assessment ◽  
Assessment Process ◽  
Case Scenario ◽  
Worst Case ◽  
Alternative Scenario ◽  
Worst Case Scenario ◽  
Port Area ◽  
Storage Facilities

Objectives : In order to conduct the quantitative risk assessment for hazardous chemical storage facilities at the tank terminal in the port area, the entire risk assessment process was performed in according to the guidances of the Korea Ministry of Environment.Methods : The risk of the facility was derived by the worst-case scenario, alternative scenario, and then evaluated by KORA program. The countermeasures of the risk were suggested by the concept of LOPA.Results and Discussion : Focusing on the worst case scenario and alternative scenario among the scenario having effet to offsite, risk can be reduced to satisfy regulation by applying measures of passive, active, and managerial.Conclusions : According to the result of risk assessment on benzene storage tank and tank lorry when port construction, the amount of storage inside the tank has a significant impact on the offsite. It is necessary to organize the risk of benzene, and comprehensive management of tank terminal storage facilities.

A semi-quantitative risk assessment model for the outbreak of grass carp hemorrhage

2013 ◽  
Vol 19 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Song YANG ◽  
Shuqin WU ◽  
Ningqiu LI ◽  
Cunbin SHI ◽  
Guocheng DENG ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Grass Carp ◽  
Assessment Model ◽  
Quantitative Risk Assessment ◽  
Risk Assessment Model
Sign in / Sign up

Export Citation Format

Share Document