Desenvolvimento de um método para diagnose de falhas na operação de navios transportadores de gás natural liquefeito através de redes bayesianas.

O Gás Natural Liquefeito (GNL) tem, aos poucos, se tornado uma importante opção para a diversificação da matriz energética brasileira. Os navios metaneiros são os responsáveis pelo transporte do GNL desde as plantas de liquefação até as de regaseificação. Dada a importância, bem como a periculosidade, das operações de transporte e de carga e descarga de navios metaneiros, torna-se necessário não só um bom plano de manutenção como também um sistema de detecção de falhas que podem ocorrer durante estes processos. Este trabalho apresenta um método de diagnose de falhas para a operação de carga e descarga de navios transportadores de GNL através da utilização de Redes Bayesianas em conjunto com técnicas de análise de confiabilidade, como a Análise de Modos e Efeitos de Falhas (FMEA) e a Análise de Árvores de Falhas (FTA). O método proposto indica, através da leitura de sensores presentes no sistema de carga e descarga, quais os componentes que mais provavelmente estão em falha. O método fornece uma abordagem bem estruturada para a construção das Redes Bayesianas utilizadas na diagnose de falhas do sistema.

Procedimento de avaliação de integridade estrutural de juntas soldadas circunferenciais em tubulações submarinas rígidas submetidas à flexão.

A demanda crescente por energia tem motivado a procura por petróleo e gás natural em ambientes com condições extremas, como operações em águas profundas e o transporte de fluídos corrosivos. Avanços tecnológicos recentes favorecem o uso de tubos de aço contendo uma camada interna resistente a corrosão (comumente chamados de Lined ou Clad Pipes) para o transporte de tais fluidos agressivos. Além disso, as tubulações submarinas são sujeitas a condições de instalação muito severas e, um caso de interesse, é o procedimento de reeling que permite com que a fabricação e inspeção da tubulação seja feita em terra. Apesar de possuir vantagens econômicas, a avaliação da integridade estrutural e especificação dos tamanhos toleráveis de trinca em juntas soldadas, nestas condições, torna-se uma tarefa complexa, devido a natureza dissimilar dos materiais e ao grande nível de deformação plástica no processo. Dessa maneira, este trabalho tem por objetivo o desenvolvimento de um procedimento de avaliação de forças motrizes elasto-plásticas em tubos contendo juntas soldadas circunferenciais sujeitos a flexão, para uma extensa gama de configurações geométricas. Dois métodos distintos foram desenvolvidos e analisados: a metodologia EPRI e o procedimento que utiliza a curva de tensão vs. deformação equivalente. As análises numéricas 3D fornecem os parâmetros de fratura necessários para a resolução do problema e a acurácia dos procedimentos é verificada a partir de estudos de casos e análises paramétricas.

Resistência à fadiga de tubo API 5L X65 cladeado e soldado circunferencialmente com eletrodos de Inconel® 625

As recentes descobertas de petróleo e gás na camada do Pré-sal representam um enorme potencial exploratório no Brasil, entretanto, os desafios tecnológicos para a exploração desses recursos minerais são imensos e, consequentemente, têm motivado o desenvolvimento de estudos voltados a métodos e materiais eficientes para suas produções. Os tubos condutores de petróleo e gás são denominados de elevadores catenários ou do inglês \"risers\", e são elementos que necessariamente são soldados e possuem fundamental importância nessa cadeia produtiva, pois transportam petróleo e gás natural do fundo do mar à plataforma, estando sujeitos a carregamentos dinâmicos (fadiga) durante sua operação. Adicionalmente, um dos problemas centrais à produção de óleo e gás das reservas do Pré-Sal está diretamente associado a meios altamente corrosivos, tais como H2S e CO2. Uma forma mais barata de proteção dos tubos é a aplicação de uma camada de um material metálico resistente à corrosão na parte interna desses tubos (clad). Assim, a união entre esses tubos para formação dos \"risers\" deve ser realizada pelo emprego de soldas circunferenciais de ligas igualmente resistentes à corrosão. Nesse contexto, como os elementos soldados são considerados possuir defeitos do tipo trinca, para a garantia de sua integridade estrutural quando submetidos a carregamentos cíclicos, é necessário o conhecimento das taxas de propagação de trinca por fadiga da solda circunferencial. Assim, neste trabalho, foram realizados ensaios de propagação de trinca por fadiga na região da solda circunferencial de Inconel® 625 realizada em tubo de aço API 5L X65 cladeado, utilizando corpos de prova do tipo SEN(B) (Single Edge Notch Bending) com relações entre espessura e largura (B/W) iguais a 0,5, 1 e 2. O propósito central deste trabalho foi de obter a curva da taxa de propagação de trinca por fadiga (da/dN) versus a variação do fator de intensidade de tensão (ΔK) para o metal de solda por meio de ensaios normatizados, utilizando diferentes técnicas de acompanhamento e medição da trinca. A monitoração de crescimento da trinca foi feita por três técnicas: variação da flexibilidade elástica (VFE), queda de potencial elétrico (QPE) e análise de imagem (Ai). Os resultados mostraram que as diferentes relações B/W utilizadas no estudo não alteraram significantemente as taxas de propagação de trinca por fadiga, respeitado que a propagação aconteceu em condições de escoamento em pequena escala na frente da trinca. Os resultados de propagação de trinca por fadiga permitiram a obtenção das regiões I e II da curva da/dN versus ΔK para o metal de solda. O valor de ΔKlim obtido para o mesmo foi em torno de 11,8 MPa.m1/2 e os valores encontrados das constantes experimentais C e m da equação de Paris-Erdogan foram respectivamente iguais a 1,55 x10-10 [(mm/ciclo)/(MPa.m1/2)m] e 4,15. A propagação de trinca no metal de solda deu-se por deformação plástica, com a formação de estrias de fadiga.

Is Europe vulnerable to Russian gas cuts? CEPS Commentaries, 12 March 2014

The EU relies heavily on imports to meet its demand for natural gas. Nearly 23% of the gas burned by the EU member states is produced in Russian gas fields. Ukraine remains one of the main supply routes for Russian gas flowing into Europe. Consequently, mounting tensions between Russia and Ukraine concerning the Crimean Peninsula brought back memories of past gas supply disruptions, most notably of 2009. The question today is whether the EU in 2014 is equally vulnerable to potential (forced or voluntary) cuts in Russian gas supplies as it was five years ago. In this commentary, Arno Behrens and Julian Wieczorkiewicz look into two different scenarios. First, could Europe sustain longer cuts in gas supplies from Russia? And second, what impact would disruptions of Russian gas deliveries to Ukraine have on the EU? Essentially the authors argue that Russia is highly dependent on gas exports to Europe, while Europe could resort to alternatives to Russian gas. In addition, Europe is much better prepared for potential short-term supply disruptions than it was five years ago.

A Gas Hub for Ukraine. CEPS Commentary, 11 June 2014

For many years, when natural gas was mentioned in conjunction with Ukraine, it meant nothing but trouble. But at the very moment when Ukraine's territorial integrity is at stake, natural gas could become part of the solution. Due to its massive storage potential, namely one-third that of the EU (or seven-times that of the UK), Ukraine is a natural candidate for an eastern European gas hub. Becoming an integrated part of the European gas market has economic and political merits – both for Ukraine and the EU.

The gas target model for the Visegard 4 Region: conceptual analysis. OSW Report, May 2013

The similarity of issues and geographical proximity have led the Visegrad 4 countries (V4) to undertake closer collaboration in natural gas policy, notably by agreeing on a common security of supply strategy, including regional emergency planning, and a common implementation of the Gas Target Model (GTM) that European regulators have proposed for the medium-long term design of the EU gas market, and which has been endorsed by the Madrid Regulatory Forum. As a contribution to this collaboration, the present paper will analyse how the GTM may be implemented in the V4 region, with a view to maximize the benefits that arise from joint implementation. A most relevant conclusion of the GTM is that markets should be large enough to attract market players and investments, so that sufficient diversity of sources may be reached and market power indicators are kept below dangerous levels. In most cases, this requires physical and/or virtual interconnection of present markets, which is also useful to achieve the required security of supply standards, as envisaged in the Regulation 994/2010/EC.

The resource wealth burden - oil and gas sectors in the former USSR. OSW Study 12/2003

The former USSR area plays a great role in the international oil and gas market. Russia is a real gas giant, with the richest deposits of this material in the world. Russia is also the main exporter of natural gas to many European countries. Keeping a strong position in this market remains a priority for the Russian Federation's economic policy. Europe is a very attractive region because its demand for gas is expected to grow steadily, while its own gas production keeps decreasing. In the long term, the Far East will be an important market for Russian exports, too. According to estimates, demand there will grow even faster than in Europe. Caspian gas producers, for the time being, can not really compete with Russia in this field, and this status quo will most probably be preserved in the nearest future.

The eastern ‘partnership’ of gas. Gazprom and CNPC strike a deal on gas supplies to China. OSW COMMENTARY No. 139, 2014-06-16

The CEOs of Gazprom and China’s CNPC signed a contract concerning Russian gas supplies to China on 21 May 2014 in Shanghai. The contract had been under negotiation for many years and was signed in the presence of the two countries’ presidents. Under this 30-year deal, ultimately 38 billion m3 of natural gas will be exported annually from eastern Siberian fields (Chayandinskoye and Kovyktinskoye) via the Power of Siberia pipeline planned for construction in 2015–2019. The lengthy negotiation process (initial talks regarding this issue began back in the 1990s), the circumstances surrounding the signing of the contract (it was signed only on the second day of Vladimir Putin’s visit to Shanghai, and the Russian president’s personal engagement in the final phase of the talks turned out to be a key element) and information concerning the provisions of the contract (the clause determining the contract price has not been revealed) all indicate that the terms of the compromise are more favourable for China than for Russia. This contract is at present important to Russia mainly for political reasons (it will use the future diversification of gas export routes as an instrument in negotiations with the EU). However, the impact of this instrument seems to be limited since supplies cannot be redirected from Europe to Asia. It is unclear whether the contract will bring the anticipated long-term economic benefits to Gazprom. The gas price is likely to remain at a level of between US$350 and US$390 per 1000 m3. Given the high costs of gas field operation and production and transport infrastructure development, this may mean that supplies will be carried out at the margin of profitability. The Shanghai contract does not conclude the negotiation process since a legally binding agreement on gas pipeline construction has not been signed and not all of the financial aspects of the project have been agreed upon as yet (such as the issue of possible Chinese prepayments for gas supplies).

First steps towards into the unknown. The possibilities prospects of unconventional gas extraction in Ukraine. OSW Commentary No. 106, 2013-04-24

Ukraine’s deposits of unconventional gas (shale gas, tight gas trapped in non-porous sandstone formations, and coal bed methane) may form a significant part of Europe’s gas reserves. Initial exploration and test drilling will be carried out in two major deposits: Yuzivska (Kharkiv and Donetsk Oblasts) and Oleska (Lviv and Ivano-Frankivsk Oblasts), to confirm the volume of the reserves. Shell and Chevron, respectively, won the tenders for the development of these fields in mid 2012. Gas extraction on an industrial scale is expected to commence in late 2018/ early 2019 at the earliest. According to estimates presented in the draft Energy Strategy of Ukraine 2030, annual gas production levels may range between 30 billion m3 and 47 billion m3 towards the end of the next decade. According to optimistic forecasts from IHS CERA, total gas production (from both conventional and unconventional reserves) could reach as much as 73 billion m3. However, this will require multi-billion dollar investments, a significant improvement in the investment climate, and political stability. It is clear at the present initial stage of the unconventional gas extraction project that the private interests of the Ukrainian government elite have played a positive role in initiating unconventional gas extraction projects. Ukraine has had to wait nearly four decades for this opportunity to regain its status of a major gas producer. Gas from unconventional sources may lead not only to Ukraine becoming self-sufficient in terms of energy supplies, but may also result in it beginning to export gas. Furthermore, shale gas deposits in Poland and Ukraine, including on the Black Sea shelf (both traditional natural gas and gas hydrates) form a specific ‘European methane belt’, which could bring about a cardinal change in the geopolitics and geo-economics of Eastern and Central Europe over the next thirty years.

Energy Union: Can Europe learn from Japan’s joint gas purchasing? CEPS Commentary, 11 December 2014

Japan’s two major electricity producing companies reached a preliminary agreement recently to establish a joint venture for the procurement of fossil fuel resources, primarily liquefied natural gas (LNG). The authors of this commentary ask whether this commercial initiative could serve as an example to Europe of how to increase the negotiating power of individual EU member states. They conclude that a private joint gas procurement company may indeed offer a solution for EU member states in Central and Eastern Europe, instead of yet another source of confrontation. Given the political volatility in the region, it could well be the key to balancing out the need for security of supply with an offer to guarantee security of demand, thereby creating the climate for stable commercial relations.

German companies strengthen their cooperation with Russian gas suppliers. OSW Commentary No. 64, 2011-10-24

Germany’s decision to give up the use of nuclear energy will force it to find a conventional low-carbon energy source as a replacement; in the short term, in addition to coal, this is likely to be gas. Due to their continued high debt and the losses associated with the end of atomic power, German companies will not be able to spend large funds on investing in conventional energy. First of all, they will aim to raise capital and repay their debts. The money for this will come from selling off their less profitable assets; this will include sales on the gas market. This will create opportunities for natural gas exporters and extraction companies such as Gazprom to buy back some of the German companies’ assets (electricity companies, for example). The German companies will probably continue to seek to recover the costs incurred in the investment projects already underway, such as Nord Stream, the importance of which will grow after Russian gas imports increase. At the same time, because of their debts, the German companies will seek to minimise their investment costs by selling some shares on the conventional energy market, to Russian corporations among others; the latter would thus be able to increase their stake in the gas market in both Western (Germany, Great Britain, the Benelux countries) and Central Europe (Poland, the Czech Republic). It is possible that while establishing the details of cooperation between the Russian and German companies, Russia will try to put pressure on Germany to give up competing projects such as Nabucco. However, a well-diversified German energy market should be able to defend itself against attempts to increase German dependence on Russian gas supplies and the dictates of high prices.

Shale gas in Europe: much ado about little? Egmont Paper No. 64, March 2014

Introduction. Shale gas is an unconventional form of gas1 because its extraction is more difficult or less economical than that of conventional natural gas. It has become an important item of energy policy during the last years since new processes have allowed its extraction. In the medium term, shale gas should foster a reinforcement of the gas part in the world’s energy mix. In 2011, the IEA released an influential report entitled “Are we entering a golden age of gas?” This report suggests that shale gas could help substantially boost global gas use.2 It also warns at the same time that this success could bring into question the international goal of limiting the long-term increase in the global temperature to 2° C above pre-industrial levels. In the world economy, the impact of shale gas is increasing rapidly (especially in the USA, albeit apparently not as significantly as expected3). In the EU, its perspectives remain uncertain, for many reasons. Estimates are not reliable. Shale gas exploitation remains a controversial issue due to geology, lack of infrastructure and also fears for the environment and public health. The EU institutions seem to have a favorable attitude towards shale gas development while the Member States’ attitude seems to vary from enthusiasm to hesitation or opposition. Public opinion on the issue appears quite divided everywhere. This brief paper will examine various estimations of potential resources in the EU (§ 1), the potential costs and benefits (§ 2), the initiatives taken by the EU institutions (§ 3) and the national authorities (§ 4), and finally the emerging EU framework (§ 5). The conclusion is, rather surprisingly, that whatever happens on this front, this will not modify the present structural challenges of the EU in the domains of climate and energy.4

Europe's LNG Strategy in the Wider EU Gas Market. CEPS Policy Brief No. 333, October 2015

In its Communication on an Energy Union published in February 2015, the European Commission committed itself to “explore the full potential of liquefied natural gas (LNG), including as a back-up in crisis situations when insufficient gas is coming into Europe through the existing pipeline system” and to address the potential of gas storage in Europe by developing a comprehensive LNG and storage strategy by the end of 2015 or early in 2016. This is a comprehensible move in the current context. Geopolitical tensions between the EU and Russia explain the EU’s willingness to further diversify its supply sources of natural gas to reinforce its long-term energy security on the one hand, and to strengthen its ability to solve future crises on the other hand. Moreover, the current market dynamics could support diversification towards LNG. Increasing the flexibility of LNG trade, decreasing LNG prices and LNG charter rates and an apparent price convergence between the European and the Asia-Pacific LNG imports would all reinforce the economic viability of such a strategy. This Policy Brief makes three main points: • For the LNG and gas storage strategy to work, it needs to be embedded in the realities of the natural gas market. • The key to a successful LNG strategy is to develop sufficient infrastructure. • The LNG strategy needs an innovation component.

Gas demand for power generation peaked as early as 2010. CEPS Commentary, 12 February 2016

The outlook for natural gas demand is often considered bright, especially for gas used to generate electricity. This is because gas is the cleanest of all fossil fuels. The carbon intensity of modern gas-fired power stations is less than 50% that of modern coal plants. Moreover, gas-fired units are well-suited to follow rapid swings in supply and demand due to their flexibility. In the future, these balancing tasks will become more and more important given the intermittent character of the supply of wind and solar power. Gas seems to hold out the promise of being a key pillar of the energy transition and the perfect partner of renewables. Given the EU’s long-term climate policy goals, however, there is strong evidence that demand for gas for purposes of power generation peaked as early as 2010.