Dissertations / Theses on the topic 'Flaring gas'

Gas flaring is the burning of unwanted produced natural gas, which cannot be processed or sold during oil and gas production and processing operations. In past decades, gas flaring was believed to be environmentally tolerable. However, scientists have found that the flaring of gas is an impediment to the environment; this has led to attempting to tackle the problem of gas flaring to advance it to an acceptable level worldwide. In this study, two options were investigated for the utilisation of natural gas that was previously flared. The first option was a theoretical investigation of the use of ceramic perovskite membranes in a tubular reactor for the partial oxidation of methane (flare gas) to syngas. The H2/C product ratio of partial oxidation of methane is 2:1, which is suitable for Fischer-Tropch technology or methanol synthesis. It was found that this option is ideal for converting natural gas into synthesis gas (CO + H2), and it reduces capital and running costs, as these membranes are able to separate oxygen from the air stream with no need for an oxygen separation plant. The novelty of this approach is that the production of syngas using oxygen selective membranes can be achieved at the “Wellhead” with no requirement for the gas to be transported and a consequent reduction in transport costs. The second option was an experimental investigation in using spraying and atomisation techniques for the generation of carbon nanotubes, by spraying simulated catalyst solution droplets into a hydrocarbon gas stream (methane as a carbon source) using a novel “atomiser device” incorporating pressure swirl atomisers. The second part of the investigation was divided into two phases: Phase-I, which was implemented at the Spray Research Group laboratory at the University of Salford, involved a series of experiments which were undertaken to produce fine aerosol droplets that have a number mean diameter of less than or equal to 5 μm, which was successfully achieved. In this phase, water and air were used to simulate the metal catalyst and methane, respectively, which were used in Phase-II. Phase-II trials were implemented at the University of Oxford on a collaborative basis. A furnace was installed underneath of the Phase-I “atomiser device” and the stream of droplet particles fell down through the furnace (400 - 800o C). Reaction inside the furnace occurred to produce the Single Wall Carbon Nanotubes (SWCNT) material. The preliminary results of the experiments in this Phase showed that it is possible to produce SWCNT. This investigation also considered an economic analysis of reducing gas flaring. A Visual Basic (VB) programme was developed to make a cost comparison between the proposed options and current conventional plants. The consideration of the economic analysis demonstrated that the cost of natural gas flaring exceeds those for syngas and Single-Walled Carbon Nanotubes production.

The World Bank has set 2030 as the year for the cessation of routine natural gas flaring in countries concerned. Nigeria is among the most consistent natural gas flaring nations on earth and natural gas flaring remains an intractable negative externality for approximately six decades of crude oil exploration in the country. With a focus on the long run, we employ the Autoregressive Distribution Lag bounds test to cointegration approach to search for the determinants of natural gas flaring in Nigeria using secondary data from 1984-2013. Empirical result identified natural gas flaring penalty, crude oil production, natural gas price, natural gas marketization and lack of natural gas infrastructure as fundamental determinants of natural gas flaring in Nigeria. Crude oil production contributed the highest to the increase in natural gas flaring while natural gas marketization has the greatest impact on gas flaring abatement. The key conclusion from this paper is that the implementation of policies targeting optimal natural gas flaring can result in natural gas flaring mitigation in the long run and put Nigeria on the path towards meeting the 2030 World Bank deadline on cessation of routine natural gas flaring.

The issue of gas flaring and the attendant environmental effects have become a common sight in the Niger Delta. Apart from being a wastage of natural resources, it is a menace to the global existence of man. The incidences of acid rain and the disruption of economic life of the locals, basically farming and fishing, have led to consistent and irresistible agitation by the people of the Niger Delta for an end to gas flaring. The consistent release of harmful gases through gas flaring, with devastating effect on the surrounding environment of the Niger Delta region is discussed in this work. This dissertation examines why successive governments have not succeeded in their quest for a solution to gas flaring; policies and regulations are not being effectively implemented, and why despite the fact that flaring has been outlawed in Nigeria since 1st January 1984, it is still going on 24 years after. Flaring continues unabated undermining the consequences it has on the people and the effects on climate change. Interviews and case studies were used to examine the factors responsible for the non implementation of government policies and regulations, and why the consistent extension of flare-out deadline. Countries with outstanding results were examined in order to draw a baseline for the Nigeria situation. The research revealed that the Nigerian government has not enforced environmental regulations effectively because of its interests in the business of the multinationals. In addition there has been the dependence of environmental monitoring and regulatory agencies on government funding. This has drastically affected the proficiencies of the control and the insignificant penalties imposed on companies that flare gas. The need for government to play the role of an umpire rather than business partner with the multinationals is therefore of paramount importance. It is also pertinent that the regulatory and monitoring agencies be independent of government's supervision. More stringent measures, (ranging from more cost per a thousand standard cubic feet of gas flared to closure of platform(s) and/or outright withdrawal of license), should also be put in place to serve as deterrent to erring oil companies.
Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2009.

This research examined the technical and economic feasibility of harnessing flare gas emissions from oil fields. The outcome would provide the basis for a substantial re-utilization of this waste energy due to the current practice of flaring and use it alternatively as energy for powering oil fields, rural electrification and desalination. Nigeria is used as a case study. Burning fossil fuels have grave environmental impact, amidst increasing global concerns over harmful emissions. This research addresses resource decline and suggests divestment as a partial cure. The gas turbine is subject to degradation of its components as it is used. Though several methods of assessing gas turbine degradation have been developed with varying degrees of success, no one method has addressed issues pertaining to associated gas and its effects on degradation with divestment. Simulation of two single shaft, heavy duty industrial gas turbines; and three aero-derivative industrial gas turbines of the heavy medium and light capacity ranges were carried out for varying operating conditions, to ascertain the effects of degradation when run on associated gas. Thereafter, optimizations for the best power plant engine mix and the least cost of electricity were carried out. Genetic algorithm was used to assess a population of 10,000 individuals over 500 generations; convergence was achieved for different configurations of the five study engines at discount rates of 5% and 10%, over three power ranges. The divestment pattern starts with the lightest aero-derivative industrial gas turbine; the best power plant selection was limited to the two lightest aero-derivatives in the fleet, completely ignoring the heavy engines. A techno-economic, environmental and risk assessment model comprising performance, emission, economics and risk modules was successfully developed to assess gas turbine degradation with divestment. Using this tool, it was confirmed that associated gas usage resulted in degradation of gas turbine performance, an increase in gas collection as well as operation and maintenance costs. Also there was increasingly higher creep life consumption during slow, medium and fast degradation scenarios for both engine sets. The novel technical contribution of the research work therefore is the influence of degradation on the economic use of associated gas as fuel in gas turbine power generation; and the implementation of divestment in the face of fuel decline.

Carbon dioxide emission due to associated natural gas flaring is among the major causes of climate change which affects the global environment adversely. Nigeria is rated as the country with second largest volume of associated natural gas being flared the world over. Dominant oil and gas companies being operated by foreign multinational oil companies have been responsible for over ninety percent of associated natural gas flaring in the Nigerian upstream sector. Aside from being waste of valuable energy resource, the damaging, environmental impact of gas flaring, along with the intense physical nature of the practice, is among the major causes of environmental-accountability-triggered conflict especially in the Niger Delta region of the country. With this in mind, this study aims at evaluating gas flaring-related environmental accountability of dominant companies operating in the upstream sector of the Nigerian oil and gas industry. This is carried out via the evaluation of gas flaring-related 'environmental performance' and 'environmental disclosure' individually and together within the same framework. Deductive research strategy underpinned by positivists' research philosophy is employed to facilitate the empirical conduct of the research. Consequently, five testable hypotheses were developed from three theories, namely, Environmental Kuznets Curve theory, Pollution Haven Hypothesis and Voluntary Disclosure Theory. Each of the five hypotheses is directly related to a specific objective, so that they can be the mechanisms for meeting the objectives. By virtue of its nature, objective six is the only objective that does not have a corresponding hypothesis. To test the five hypotheses and also explore objective six, a number of analytical tools were employed. They include DEA window analysis, content analysis, one sample hypothesis test for mean, correlated two sample Hest for means, Panel Corrected Standard Errors (PCSE) using Prais-Winsten regression and simple time-series Ordinary Least Squares (OLS) regression in the first difference. Results obtained enabled the documentation of important key findings. Thus, the study documents empirical evidence confirming that the elements of gas flaring-related environmental accountability, namely, 'environmental performance' and 'volumetric environmental disclosure' are adverse and inadequately low respectively; and that the relationship between them is significantly positive. The 'substance' of the disclosure is also found to be not superior. It is also found that dominant companies in the sector use 'specific' or 'hard' gas flaring-related information that gives positive reflection on their reputation to legitimise their associated gas flaring and production activities. All these support the evidence, provided in this study, that gas flaring-related environmental responsibility, reporting and, in general, accountability by dominant companies in the Nigerian upstream are poor. The significance of these major findings is evident in the empirical support they lend to Environmental Kuznets Curve theory, Pollution Haven theory and Voluntary Disclosure Theory in the context of a less developed country, and the confirmatory empirical evidence that 'consequentialism' is the dominant environmental moral philosophy in the Nigerian upstream sector. The significance of the findings is further indicated by providing evidence that change in gas flaring-related environmental performance is responsible for the undulating trends in the level of environmental disclosures by companies operating in less developed countries over time.

Through the Global Gas Flaring Reduction (GGFR) initiative a substantial amount of effort and international attention has been focused on the reduction of gas flaring since 2002 (Elvidge et al., 2009). Nigeria is rated as the second country in the world for gas flaring, after Russia. In an attempt to reduce and eliminate gas flaring the federal government of Nigeria has implemented a number of gas flaring reduction projects, but poor governmental regulatory policies have been mostly unsuccessful in phasing it out. This study examines the effects of pollution from gas flaring using multiple satellite based sensors (Landsat 5 TM and Landsat 7 ETM+) with a focus on vegetation health in the Niger Delta. Over 131 flaring sites in all 9 states (Abia, Akwa Ibom, Bayelsa, Cross Rivers, Delta, Edo, Imo, Ondo and Rivers) of the Niger Delta region have been identified, out of which 11 sites in Rivers State were examined using a case study approach. Land Surface Temperature data were derived using a novel procedure drawing in visible band information to mask out clouds and identify appropriate emissivity values for different land cover types. In 2503 out of 3001 Landsat subscenes analysed, Land Surface Temperature was elevated by at least 1 ℃ within 450 m of the flare. The results from fieldwork, carried out at the Eleme Refinery II Petroleum Company and Onne Flow Station, are compared to the Landsat 5 TM and Landsat 7 ETM+ data. Results indicate that Landsat data can detect gas flares and their associated pollution on vegetation health with acceptable accuracy for both Land Surface Temperature (range: 0.120 to 1.907 K) and Normalized Differential Vegetation Index (sd ± 0.004). Available environmental factors such as size of facility, height of stack, and time were considered. Finally, the assessment of the impact of pollution on a time series analysis (1984 to 2013) of vegetation health shows a decrease in NDVI annually within 120 m from the flare and that the spatio-temporal variability of NDVI for each site is influenced by local factors. This research demonstrated that only 5 % of the variability in δLST and only 12 % of the variability in δNDVI, with distance from the flare stack, could be accounted for by the available variables considered in this study. This suggests that other missing factors (the gas flaring volume and vegetation speciation) play a significant role in the variability in δLST and δNDVI respectively.

The rapid development of the global oil and gas industry has led to an increase in atmospheric emissions which is detrimental to the wider atmosphere. The flaring of gas during oil exploration and production (E & P) activities alarmingly contributes to the emission of green-house gases which contribute to climate change. The enactment of legislation with adequate provisions for the reduction and elimination of gas flaring from oil and gas activities is very important. Very few countries in the world (e.g. Canada) have been able to successfully eliminate the problem of gas flaring through conservation and the enactment of adequate legislation with stringent sanctions for defaulters who continue flaring. Nigeria is an example of a country with inadequate gas flaring laws. This thesis examines the effectiveness of regulatory regimes on gas flaring in Nigeria with a view to determining if the phase-out of the problem can be achieved. It stipulates that the provisions of the Associated Gas RE-Injection Act (AGRA) 1979 and its Regulations of 1984 are inadequate for the regulation and or elimination of gas flaring. It also advocates for the amendment of AGRA, the development of more effective laws on gas flaring and methods by which the gas being flared can be conserved in order to ensure a clean and healthy environment in Nigeria (particularly the Niger-Delta), free from gas flares.

Gas flaring, the disposal of gas through stacks in an open-air flame, is a common feature in the processing of crude oil, especially in oil-rich regions of the world. The rates of emission of pollutants from gas flaring depend on a number of factors including, but not limited to, fuel composition and quantity, stack geometry, flame/combustion characteristics, and prevailing meteorological conditions. In this work, new estimated emission factors (EFs) for carbon-containing pollutants (excluding PAH) are derived for a specified subset of flame condition. The air pollution dispersion model, ADMS5, is used to simulate the dispersion of pollutants from gas-flaring stacks in the Niger delta. Fuel composition and flare size play significant role in the dispersion pattern and ground-level concentrations of pollutants. To assess the significance of gas-flaring to atmospheric aerosol loading, AERONET aerosol signals are clustered using trajectory analysis to identify dominant aerosol sources at the Ilorin site (4.34o E, 8.32o N) in West Africa. From 7-day back-trajectory calculations over a 10-year period calculated using the UK Universities Global Atmospheric Modelling Programme (UGAMP) trajectory model, which is driven by analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF), dominant sources are identified, using literature classifications: desert dust, biomass burning, and urban-industrial. Using a combination of synoptic trajectories and aerosol optical properties, a fourth source is distinguished: that due to gas flaring. An estimation of the relative impact of these different aerosol sources on the overall radiative forcing at the Ilorin AERONET site was the carried out.

This research is concerned with the application of experimental and numerical methods to the investigation of gas flares. Gas flares are ubiquitous in the oil and gas industry and knowledge of the emissions from flares are of vital importance. Also, flares subjected to a cross-wind behave differently from flares in quiescent atmosphere and the stability of flares are important due to the possibility of blow offs in strong cross-winds. Natural gas flares are common on oil and gas production fields and given that natural gas is predominantly methane, many researchers have carried out numerical studies on methane cross-flow flames. In the present study, a propane cross-flow flame has been numerically investigated in addition to the investigations on methane and the predicted results have been compared against experimental data. The first chapter presents an introduction to the topic of gas flares and also outlines the objectives of the project. The second chapter presents a review of the literature on related topics. The third chapter presents the methods of investigation employed in this thesis. The fourth, fifth and sixth chapters present the results of the investigations carried out while the final chapter gives the general conclusions and suggestions for future investigations. The numerical aspect of the work investigates the capability of the existing codes in the ANSYS Fluent software to predict propane flares both with and without cross-flows. Comparisons have been made between the non-premixed and the partially premixed combustion models in their capability to predict wake-stabilized cross-flow flames. Also, the results obtained using the Reynolds stress turbulence model was compared against the Large Eddy Simulation technique with the latter showing better predictions for the temperature and species. The reaction mechanism of Ranzi et al. (2012) was used to model the kinetics of the propane reactions while the GRI 3.0 was used to model the kinetics of the methane reactions. Soot in the propane flame was modelled with the Moss-Brooke-Hall model. The experimental aspect of the work involved comparing the lift-off behaviour of the methane and the propane flames given the effect of lift-off on the emission from the flames.

It is evident from research that there is a strong link between poor indoor environments, external façade of school buildings, schoolchildren’s health and academic performance. In order to provide a better indoor environment for schoolchildren, meeting strict criteria in relation to indoor air quality (IAQ), thermal comfort, aesthetics and longevity is highly important. Stringent health criteria for school buildings’ design and construction have led to innovations in selecting and manufacturing of materials that meet such criteria. However, the uses of prescriptive specification and outdated national building codes have proved to be challenging leading to the application of Performance Specification (PS). The prescriptive method, unlike the PS which permits innovation, is disruptive and cumbersome; using codes that hamper the adoption of newer and safer materials for today’s environmental challenges. This study developed a guidance document known as a PS to aid the design, selection of materials and construction of schools buildings in the Niger Delta area (NDA) where gas flaring (GF) is predominant. This excessive pollution poses the biggest challenge to indoor environments and building deterioration. School buildings in Nigeria currently follow the prescriptive specification and national building codes that were last updated in 2006. Such practices are clearly inadequate for tackling environmental challenges in the NDA. Therefore, PS, based on performance requirements and fit for purpose, is more likely to help in achieving clean indoor air and durable external façade of school buildings in the vicinity. The study adopted the design science (DS) method as the philosophical approach due to its advantages in integrating other research strategies. Literature on GF impacts and the use of PS was reviewed followed by qualitative and quantitative data collection using both open-ended questionnaire and semi-structured interview. While 120 open-ended questionnaires were administered, 102 valid responses were retrieved and 10 expert professionals with more than ten years of experience in professional practice in the primary area of study were interviewed. Consequently, the data that emerged were analysed using Nvivo 11 and SPSS to identify specific environmental issues for potential mitigation. The final PS was demonstrated in three iterative processes through subsequent data collection exercise using open-ended questionnaires administered to 102 respondents to provide the required environment specific requirements for design and construction purposes. This was carried out through experienced professionals and evaluated by potential dominant users in the study area. It concludes that the developed PS will potentially change current practices in terms of design and selection of materials for school construction. The use of PS as opposed to the sole reliance on the Nigerian building code which is prescriptive in nature is deemed feasible. The research outcomes also included the development of immediate environmental criteria for limits on hazardous substances and space cooling levels for performance requirements, among others. In addition, innovative triple and double filtration systems for use as air purifiers without energy costs were designed. These locally tailored criteria provide environment specific requirements without mirroring international codes to offer clean IAQ for the research environment. It is expected that the DPS would be used by professionals in the Built environment and policy makers as a guiding tool during the design, selection and construction of buildings in the VGF and/or for (re) designing and renovation process to meet growing indoor air quality needs and achieves building durability in the NDA.

Oil extraction in Nigeria has caused extensive environmental degradation and health problems in many Nigerian communities, particularly in the ecologically sensitive Niger Delta where nearly all of the oil extraction takes place. The reasons for this are complex and have roots in Nigeria’s colonial past. The Nigerian economy is largely reliant on its petroleum resources which, in conjunction with governmental corruption and high international demand for Nigerian oil, has created a system where environmental externalities are largely ignored. Multinational oil companies with little stake in the development and environment of Nigeria are responsible for most of the extraction projects and subsequent environmental damage. However, the Nigerian federal government has failed to effectively regulate these projects. Communities in the Niger Delta bear nearly all of the environmental burden of oil extraction, but see very little of the economic benefits. The main environmental impacts of oil extraction are oil spills, land use change, and gas flaring. Oil spills are very common in the Niger Delta. Cleanup efforts are often inadequate, resulting in loss of delicate ecosystems as well as fisheries and farmland. Large tracts of rainforest and mangrove ecosystems have been cleared or degraded by the oil extraction process. Nigeria flares more gas per barrel of oil extracted than any other country in the world, contributing to global warming and creating serious health hazards for communities located near gas flares. Diversification of the Nigerian economy would help to alleviate many of the factors that lead to environmental degradation, including the dependence of the government on oil revenues, high unemployment, and rampant oil theft. Curbing government corruption is also vital to effective regulation of oil extraction. International consumers can help Nigeria head towards a less petroleum-driven future through an increased awareness of the origins of their oil and pressure on the Nigerian federal government and the multinational oil companies to extract oil more conscientiously or even to discontinue oil extraction. But most importantly, the solution to Nigeria’s economic concerns must ultimately come from Nigerians as international influence has been a major contributor to the environmental degradation in the first place.

Bei der Förderung von Erdöl wird auch Erdgas gefördert, das oft abgefackelt wird. Das Abfackeln von Erdgas ist sehr schädlich für die Umwelt und die Bewohner einer Umgebung in der Gas abgefackelt wird. Demzufolge ist die Reduktion dieses Prozesses eine wichtige Aufgabe, die durch Monitoring von Gasfackeln unterstützt werden kann. Dies gelingt am besten durch Fernerkundung mit Satellitendaten. Die vorliegende Dissertation widmet sich der Parametrisierung von Gasfackeln anhand von Infrarot-Satellitenaufnahmen. Eine Gruppe von Sensoren wurde verglichen, woraus optimale Eigenschaften eines Sensors zur Gasfackelanalyse abgeleitet wurden. Danach wurde ein Modell zur Berechnung des Gasflusses aus Infrarot-Satellitenaufnahmen entwickelt. Das vorgeschlagene Modell basiert auf der Physik der Verbrennung und wird von Teilmodellen zur Berechnung der Verbrennungsparameter unterstütz. Dadurch werden Prozesse mitberücksichtigt, die bisher in der Gasfackelforschung wenig adressiert wurden. Eine Experimentenreihe erlaubte eine Charakterisierung der Flamme in Bezug auf sich verändernde Bedingungen, z.B. Gasfluss. Zusätzlich wurde das Modell durch die Experimente validiert. Die abgeleitete Genauigkeit der Gasflusswerte ist verhältnismäßig hoch, insbesondere wenn man die Komplexität und Variabilität einer Gasflamme berücksichtigt. Durch Analysieren des Sensordesigns des BIROS Sensors aus der FireBIRD-Mission des Deutschen Zentrums für Luft- und Raumfahrt konnten die Sensorparameter charakterisiert und deren Einfluss auf ein abgeleitetes Bildprodukt quantifiziert werden. Die Fähigkeit des Modells mit unterschiedlichen Sensordaten zu funktionieren, wurde geprüft durch einen Vergleich der geschätzten Gasflusswerte aus Daten von zwei Satellitensensoren. Die verglichenen Gasflusswerte sind sehr ähnlich, was die Fähigkeit des Models mit unterschiedlichen Daten gut zu funktionieren, bestätigt. Das vorgeschlagene Model hat Potenzial, das globale Monitoring von Gasfackeln zu verbessern.
Routine gas flaring is harmful to the environment and people living in the vicinity of gas flares. Therefore, the reduction of this process is an important task, which can be supported by monitoring of gas flares, which can be done with remote sensing techniques. The presented work is devoted to the monitoring of gas flaring. The first aspect of the analysis was to compare a group of sensors with respect to the features crucial for gas flaring analysis. A set of requirements for an optimal sensor for this purpose was proposed. Next, a model for calculating gas flow from infrared satellite imagery was proposed, which relies on several other models, allowing to derive the values of the combustion parameters. By modelling these parameters in a gas flare, processes are accounted for that were scarcely addressed in the research conducted on gas flaring until now. To describe the characteristics of the flame coming from combustion in a flare, an experimental series was designed and conducted. The experimental series allowed to characterise the flame with respect to changing conditions, e.g. gas flow. Thus, the characteristics derived from the experiments could be included in the model for gas flow calculation. Additionally, the experiments served as a mean to validate the model. The accuracy of the derived gas flow values is relatively high, especially considering the variability of a gas flare flame. One design goal of the model for gas flow calculation was to ensure feasibility to work with data from different sensors producing equally accurate results. By analysing the design of the BIROS sensor of the DLR, the sensor parameters could be described, and their influence on the resulting imagery could be quantified. The feasibility was verified by comparing the gas flow values calculated using data from two different satellite sensors. The results obtained are very similar. The model proposed reveals potential to improve the global monitoring of gas flaring.

Numa unidade offshore de produção de petróleo, o gás produzido é tratado para atingir as especificações requeridas e permitir sua utilização em diferentes demandas como gás combustível, gas lift, exportação de gás ou injeção de gás. No Brasil, a Agência Nacional do Petróleo regula a produção de óleo e gás, limita a queima de gás e controla a movimentação e utilização de gás de acordo com as estimativas informadas pelo operador. Falhas no sistema de tratamento de gás levam à queima e podem causar parada de produção. A confiabilidade e disponibilidade do sistema de tratamento de gás é uma preocupação relevante. Entender as relações e influências dos vários subsistemas e equipamentos do sistema nessas medidas de desempenho pode levar a melhorias nas estratégias de manutenção que podem minimizar perdas na produção de óleo e de gás. Dentre os vários métodos de análise de confiabilidade, as redes de Petri estocásticas se destacam quando comparadas às ferramentas tradicionais como diagrama de blocos ou árvore de falhas devido a sua habilidade em modelar aspectos como dependências funcionais, lógicas e sequências. Nesse trabalho foram construídos quatro modelos utilizando redes de Petri estocásticas para analisar a disponibilidade do sistema de tratamento de gás. A facilidade de construção modelo A sugere sua utilização em etapas preliminares de projeto para validar o arranjo inicial, as quantidades de equipamentos e as configurações de redundância. O modelo B pode ser utilizado para identificar os subsistemas e equipamentos que mais contribuem para as falhas do sistema e para realizar previsões quanto aos modos de operação do sistema e índice de aproveitamento de gás. A análise de sensibilidade dos resultados de disponibilidade quanto aos dados de falha utilizados mostrou que a variação do tempo médio para reparo tem maior influência. Por meio do modelo C verificou-se que uma plataforma operando num conjunto e sujeita a restrições de importação e exportação de gás tem maior indisponibilidade e maior probabilidade de falha do que uma plataforma operando isolada. O modelo D permite concluir que a inclusão de um modo de falha ao modelo não implica em variação significativa dos resultados de confiabilidade e que nos resultados de disponibilidade a variação passa a ser significativa quando adotam-se pequenos valores de tempo médio entre falhas e grandes valores de tempo médio para reparo. A construção das redes de Petri estocásticas para o sistema completo exige uma compreensão detalhada do funcionamento do sistema em análise o que também pode ser destacado como uma vantagem das redes de Petri estocásticas, contribuindo para aquisição de conhecimento acerca do sistema e dando segurança quanto a fidelidade do modelo criado.
In an offshore oil production facility, produced gas is treated to meet the necessary specifications to allow its use in different demands, as gas fuel, as exportation gas and as injection gas. In Brazil, the National Petroleum Agency regulates oil and gas production, establishing and gas flaring limits, the utilization and distribution of gas according to the operator\'s estimations. Failures in the gas treatment system eventually can cause oil production interruptions to avoid attaining the gas flaring limits. Reliability and availability of the gas treatment system is a major concern. Understanding the relationships and influences of the various gas treatment subsystems and equipment on these performance measures may lead to design or maintenance strategies improvements that could ultimately minimize oil and gas losses in the facility. Among several modelling methods stochastic Petri nets stands out comparing to traditional reliability tools like reliability block diagrams or fault tree analysis due to its ability to model aspects such as functional dependencies, logics and sequences. In this work, four models were built using stochastic Petri nets to assess the availability of a gas treatment system. The model A is easy to build and may be used in preliminary design stages to validate the initial arrangement, equipment and redundancies. The model B may be used to identify subsystems and equipment that most contribute to system failures and to predict operation modes and efficiency in the gas utilization. The sensibility analysis of reliability data has shown a predominant influence of the mean time to repair. Using model C, it could be noticed that a platform operating in a group submitted to injection and exportation gas limits has a greater unavailability and probability of failure than an isolated operating platform. Model D allow one to conclude that including a failure mode in the model does not imply in significant variation in the reliability results and that the variation is only significant in availability when using small mean time to failure values and large mean time to repair values. The stochastic Petri nets construction for the complete system requires an accurate comprehension about the system operation what could also be mentioned as an advantage of the stochastic Petri nets.

The goal of this study is to examine the environmental impacts of oil and gas exploration and production (E&P), the roles of legislation, and the environmental management strategies in the petroleum industry with respect to the Niger Delta region of Nigeria. The study seeks to suggest sustainable solutions to the endemic economic, social, and environmental problems associated with oil and gas E&P in the region. The focus is on the environmental control in the upstream (E&P) operations of the oil and gas industry as it affects the Niger Delta region of Nigeria with a view to proffering sustainable solutions.

The heavily polluting activities and environmental impacts of the upstream oil and gas operations in the Niger Delta have over the years taken a routine dimension and are endemic as a result of inadequate environmental legislations and ineffective enforcements. Sequel to these environmental impacts is militancy, adoption of expatriates, communal conflicts, inter-ethnic conflicts, human right abuses, restiveness and other social vices as the study reveals. These social and environmental impacts of oil and gas activities in this region bring impoverishment, abject poverty, hunger, squalor, birth disease, gene mutation, and death while exposing inhabitants of the region to afflictions and diseases as the study explicitly documents.

The study also reveals that the persistence rate of unrest, restiveness, militancy and other social vices is as a result of non-dialogue status between the different stakeholders, lack of infrastructural development, lack of basic amenities, high rate of unemployment, poor policy construct, federalized mineral right / resource ownership structure, and the monopolistic nature of Nigeria’s foreign exchange earning in petroleum resources.

In this dissertation, both proactive and corrective measures to curb the menace of the social, economic and environmental impacts of oil and gas exploration & production operations in Nigeria are presented and discussed with suggestions to sustainable solution and development, better environmental legislation, and better resource policy construct while advocating for good industrial practices in the petroleum industry with emphasis on the Niger Delta region of Nigeria.

The need for energy and the associated economic benefits from the oil and gas deposits found mainly in the Niger Delta region of Nigeria necessitated the exploration and exploitation activities being carried out by the oil and gas Companies. However, these exploration and exploitation activities due to their unpredictable nature have a huge potential for environmental pollution as been experienced in the form of oil spills, gas flaring, irresponsible disposal of waste and several other activities that have resulted in the environmental degradation of the Niger Delta region. In the light of these, the Federal Government of Nigeria having experienced the consequences of pollution of the environment during the Koko Toxic Waste Dump incident in the then Bendel State in 1987 established a regulatory body tasked with the responsibility of harmonizing the economic interest from the oil and gas exploration and exploitation activities with the sustainability of the natural environment by developing well structured and articulated policies aimed at guiding the operations of the oil and gas operators, track their compliance and administer appropriate punitive measures for non compliance. However, this research work which is aimed at evaluating the impact of the environmental protection policies in upstream oil and gas activities in the Niger Delta region, involved the use of questionnaires and interviews. These questionnaires were completed by the management and staff of three major oil and gas companies operating within the area, the Department of Petroleum Resources and members of the Host communities. The interview was carried out to provide relevant feedback on their assessment of the impact made by the environmental protection policies on the upstream oil and gas activities in their operational areas/host communities. The study however concluded that “Although there is a regulatory body tasked with the responsibility to develop, implement and track compliance of the environmental protection policies in the upstream oil industry, the body is ineffective and as such the impact of the environmental protection policies is inadequate. Appropriate informed recommendations on the improvement strategies to the identified gaps that resulted in the unfavorable conditions were also provided.
Thesis (M.Ing. (Development and Management Engineering))--North-West University, Potchefstroom Campus, 2011

Natural gas flaring from oil production is a pervasive yet understudied environmental issue. Recently available satellite imagery of gas flares has increased public awareness and concern over the severity and ubiquity of the problem. In the US, the relatively recent combination of hydraulic fracturing and horizontal drilling sparked the shale boom, leading to hundreds of thousands of wells being drilled within a decade, often in close proximity to residential populations. A major oil state that has emerged from the shale boom is North Dakota. In 2014, state regulators introduced a policy to limit the percentage of produced gas that oil-extracting companies are allowed to flare. Like many other places where flaring takes place, flared volumes are reported by oil companies themselves. What was the effect of North Dakota’s regulation on gas flaring according to self-reported and satellite data? What was the effect of the regulation on self-reporting behavior? In such a tight oil setting, how well does the prevailing satellite product used to monitor gas flares perform? This dissertation uses new data and methodologies from several disciplines to study these important questions around gas flaring. The results find that the predominant satellite product does not perform well in the on-shore oil production context. While regulation has reduced flaring in a major oil state, the reduction is smaller than thought because of underreporting by oil well operators. Further, the underreporting is associated with political economy and corporate culture factors.