As oil and gas projects explore more and more challenging territories, and as public opinion is increasingly aware of risks from drilling operations, it is of furthermost importance to better understand and systematically manage these risks.For every well project on the Norwegian sector, the risks from a blowout are studied from the safety and the environmental perspective, through Quantitative Risk Assessments and Environmental Risk Analyses, respectively. The blowout characteristics (probability, flow rates, durations) are among the most influent input parameters for these analyses. Traditionally these parameters have been extracted from available historical statistics from blowout databases. These databases provide generic data with very limited consideration for the well and operation specific characteristics (e.g. exploration, development, HPHT).DNV has developed a methodology for the assessment of blowout risks in order to better understand them and to be able to provide a more realistic risk picture. A multidisciplinary approach is applied during the risk assessment process, assessing the drilling or well operations according to a set of predefined criteria or risk factors. This benchmarking analysis is used as a basis for assessing the probability of a leak or a blowout. Well flow simulations are used and adjusted in order to assess the well specific leak and blowout rates for the different operations. The potential leak and blowout durations are calculated using statistical models and taking into account the context of the drilling and well operations.This new method considers the field specific reservoir challenges, best available technology and best operational practices in order to generate a more field and operation specific risk exposure. The results are more accurate risk predictions. Traditional analysis may be too conservative and would typically not reflect the actual well conditions, barriers and operational steps. Relevant examples from the Norwegian sector are presented.
Following the April 2010 Gulf of Mexico (Macondo) oil spill and the 2009 Montara incident in Australia, the International Association of Oil and Gas Producers (OGP) formed the Global Industry Response Group. This Group identified nineteen oil spill response recommendations (OGP, 2011) that are being addressed via an Oil Spill Response Joint Industry Project (OSR-JIP) during 2012–2014. The OSR-JIP is managed by IPIECA on behalf of OGP, in recognition of IPIECA's long-standing experience with oil spill response matters. One of the nineteen recommendations concerned the development of an international guideline for offshore oil spill risk assessment and a method to better relate oil spill response resources to the risk level. Consequently, the OSR-JIP has published a guideline covering oil spill risk assessment and response planning for offshore installations. This paper describes the development and content of the guideline, including how the oil spill risk assessment process provides structured and relevant information to oil spill response planning for offshore operations. The process starts by defining the context of the assessment and describing the activity to be assessed. Thereafter it addresses a series of key questions:What can go wrong, leading to potential release of oil?What happens to the spilled oil?What are the impacts on key environmental - both ecological and socio-economic - receptors?What is the risk for environmental damage?How is the established risk utilised in oil spill response planning? The guideline draws on existing good practices in the determination of oil spill response resources. It promotes consideration, in tactical and logistical detail, of the preferred and viable response strategies to address scenarios covering the range of potential oil spills up to the most serious. The methodology to evaluate the potential spill scenarios utilizes a series of questions:What are the viable techniques/strategies to deliver response with greatest net environment benefit?What are the tactical measures required to implement the identified response strategies, considering technical, practical and safety factors?What Tiered resources are required to mount the tactical measures and achieve effective response? The paper summarizes the useful tools, key information and the necessary level of detail essential to perform an oil spill risk assessment for use in oil spill response planning.
An Environmental Risk Analysis (ERA) was conducted as a pilot study on the Dalia Total FPSO (Floating Production and Storage unit) in Angola located at about 135 km off the coast with complex subsea installations at 1400m depth. The environmental damage and its frequency resulting from the drift and fate of oil depend on many physical, chemical and environmental parameters like the location and composition of the spill, oil weathering, complex and variable surface wind and current patterns, weather conditions, sensitivity of the environmental resource etc…The detailed ERA can only be done if one can estimate the probability of a given quantity of oil to reach an environmental resource and the resulting environmental damage. The possibility to use 3D oil spill drift simulation to fulfill these technical requirements and fit with the Total HSE Reference Framework and risk Matrix is tested. The TOTAL HSE Reference Framework requires that technological risk assessments are carried out for all installations. Based on the technological risk assessment of Dalia FPSO, accidental spill scenarios were compiled and aggregated to a set of most representative scenarios including one blow out case. For each spill scenario, oil drift simulations were conducted in stochastic mode with the OSCAR model developed by Sintef i.e. repeated 246 times for a period of 5 years where met-ocean data were available. Quantities of oil and associated probabilities of presence were calculated for each cell of the model. Environmental target were identified and positioned within a Geographical Information System (GIS) also used in simulations. Environmental damages were estimated based on the MIRA method. Based on these data accidental spill scenarios could be positioned on the Total risk matrix. The pilot results as well as the acceptability of the uncertainties related to this approach are discussed.
While many parameters influence the environmental consequences of oil spills, the quantity of oil released remain one of the most important. The total volume may be expressed as the leak rate multiplied with the duration of the discharge. By detecting a spill at an early stage, it could be possible limit the duration and hence the amount spilled. Early detection can also instigate a rapid response, which is another crucial consequence reducing measure. Detection technologies are becoming increasingly important as the petroleum industry is progressing into Arctic areas and closer to shore or environmentally sensitive areas. With increased environmental concerns and stakeholder engagement, company integrity and accountability are essential for maintaining a license to operate. The requirement for leak detection capabilities for oil and gas activity varies. At the Norwegian Continental Shelf, operators are required to detect pollution of significance within a short time, usually between one and three hours. Leak detection systems must also be effective regardless of darkness, sight and weather conditions. On behalf of the Norwegian Oil and Gas Association, a methodology was developed for assessing and selecting remote measurement techniques for specific fields. For the leak detection system to be effective and reliable, it is vital to select appropriate techniques that complete and complement each other. The methodology firstly maps relevant requirements, risks, facility limitations and field specific factors. A BAT (best available techniques) framework is used to identify appropriate technologies, while gap analyses may map the overall limitations and flaws by comparing a proposed system’s performance with the requirements. Gaps and/or weaknesses are further evaluated through an ALARP (as low as reasonably practicable) analysis assessing the cost and benefits of additional techniques. The methodology provides the operators with valuable information concerning factors affecting the performance. Finally, organizational measures are crucial for ensuring effective operations and it is necessary to integrate leak detection into facility management systems. This paper presents the complete methodology and explains how a structured approach can be applied to both existing and new installations. It provides examples of how assessments are conducted and an overview of the most relevant remote sensing techniques. The methodology has been reviewed by several operators and been employed for numerous projects. While the framework was developed for the Norwegian sector, it is relevant and applicable for installations globally.
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