Influence of old rectangular repair patches on the burst pressure of a gas pipeline

Seven full scale hydrostatic burst tests were carried out on pipes extracted from an API 5LX52 gas pipeline that contained rectangular and elliptical fillet welded patches and other repairs of different geometries. All breaks took place after widespread yielding. This analysis shows that the patches that generate greater risks are those that: (1) were attached to the pipeline at very low pressure, (2) were placed to repair large defects, (3) are rectangular, long in the direction of the pipe, and narrow, (4) the quality of the weld is doubtful. Based on data reported by In Line Inspection (ILI), of the four conditions mentioned above, only the third can be assessed in order to quantify risks and to schedule replacements.     

Procedures for the strain based assessment of pipeline dents

A criterion for strain-based assessment of dents in gas pipelines has been recently proposed in the ASME B31.8 code. This work initially presents a critical review of the equations for estimating strains presented in Appendix R of that code. Next, a procedure based on B-spline curves is presented that interpolates dent geometry from data measured by in-line inspection (ILI) tools and evaluates strain components. The paper proceeds with studies to assess the influence of the ILI tool resolution and positioning on the estimation of the circumferential bending strain. Finally, the evaluation of longitudinal membrane strains is assessed by taking two alternative definitions for dent length that enters in the formula proposed in Appendix R of the aforementioned code, and comparing with results provided by Finite Element analyses. The comparison suggests that directions on how to measure the dent length might be incorporated in a revision of the ASME B31.8 Code.     

Investment decisions in electricity transmission in Argentina: The role of earmarked funds and gas pipeline expansions

This paper reexamines the problem of collective decisions of investment in electricity transmission in Argentina in the nineties. We summarize our previous results on the existence of a fundamental flaw in the evaluation of willingness-to-pay and on the need to consider the votes of groups of generators integrated through common ownership rather than individual generators. We discuss the workings of the SALEX account for financing expansions and confirm that the imperfect identification of voters could affect the evaluation of expansion projects. We also study an integrated model that considers two alternatives to electricity transmission: gas transmission and the location of generators; we show that location in the demand node voting against expansions in electricity transmission could be justified to maximize profits.     

Transitioning a bus transit fleet to hydrogen fuel: A case study of Knoxville Area Transit

The current climate crisis and recent world events, including the global economic crisis and growing concerns over the availability and cost of petroleum fuels, has sparked a global interest in developing alternative, sustainable, clean fuel technologies for the transportation sector. While a multitude of alternative fuel and vehicle technologies have been presented, hydrogen is considered by many as an option of choice. However, the mass-adoption of hydrogen presents many challenges, including appropriate refueling infrastructure supply transitions, consumer vehicle purchase behavior, and fuel costs. Early fleet adoption is one proposed strategy to transition hydrogen use in the transportation sector. Bus-transit demonstration projects have proven the technology, yet there has not been large-scale adoption by transit fleets. This paper addresses infrastructure, vehicle, and personnel needs to support the transition of a medium sized transit agency to full conversion to hydrogen fuel, using Knoxville Area Transit (KAT) as a case study. Specifically, requirements for hydrogen bus fleets, production, storage, refueling and maintenance facilities, and personnel are addressed as well as the transition strategy for implementing the technology.     

The role of buying consortia among SMEs in the electricity market in Italy

We model the electricity market in Italy, focusing on the impact of buying consortia among SMEs on the behaviour of the large electricity producers and sellers. We show that consortia may in certain circumstances produce a pro-competitive result, i.e. they may induce a reduction of prices not only for consortia members but also for firms not in the consortia.     

Economic impacts of higher oil and gas prices: The role of international trade for Germany

The analysis concentrates on direct and indirect price increases, induced shifts in international trade and structural changes in the oil importing economies. The paper at hand asks, whether a stabilizing effect via international trade and domestic structural change on the GDP of oil importing countries can be observed, if a permanent oil price increase occurs. At least for Germany, structural change from consumer goods to investment goods industry and an improvement of international competitiveness limit negative impacts of increased energy prices. Analysis is based on the extensive and disaggregated global GINFORS model and the detailed INFORGE model for the German economy.     

Hydrogen permeation and distribution at a high-strength X80 steel weld under stressing conditions and the implication on pipeline failure

Hydrogen permeation and distribution at pipeline welds is critical to integrity maintenance of the pipelines, especially for those made of high-strength steels. The situation becomes even more important under stressing conditions. In this work, metallographic characterization and micro-hardness measurements were conducted at an X80 steel weld. Potentiodynamic polarization and electrochemical hydrogen permeation testing were performance at various zones at the weld, along with numerical modeling of hydrogen distribution at the zones. The X80 steel contains a microstructure of bainite bundles and polygonal ferrite. There are more polygonal ferrite, fewer bainite and some segregated cementite at heat-affected zone (HAZ). The weld metal is featured with acicular ferrite and some grain boundary ferrite. HAZ softening occurs at the weld. The hardness of the weld metal, HAZ and base steel is about 290, 248 and 261 HV_0.2, respectively. There is the greatest corrosion current density, i.e., corrosion rate, at HAZ under both elastic and plastic stresses. An applied stress further increases the corrosion current density. Under the plastic stress of 1.1σ_ys (σ_ys is yield strength), the corrosion current densities of HAZ, base steel and weld metal are 41.04, 17.03 and 25.49 μA/cm², respectively. There are always the greatest hydrogen trapping density and the smallest hydrogen diffusivity at HAZ. Hydrogen, once penetrating the welded steel, tends to accumulate at the HAZ, compared with other two zones. When the welded steel is under stresses, especially a plastic stress (i.e., 1.1σ_ys), the hydrogen diffusivity and permeability decrease, while the subsurface hydrogen concentration and hydrogen trapping density increase remarkably. Plastic deformation favors the hydrogen permeation and trapping at weld, especially the HAZ, to elevate the susceptibility to hydrogen damage. The hydrogen distribution at different welding zones can be evaluated and determined by a developed modeling method.     

Analysis of electrochemical hydrogen permeation through X-65 pipeline steel and its implications on pipeline stress corrosion cracking

Electrochemical hydrogen permeation tests were performed to measure the hydrogen permeation current through the X-65 pipeline steel in the electrolytes simulating the soil conditions to initiate near-neutral pH stress corrosion cracking (SCC) in pipelines. The hydrogen permeation current was analyzed following the constant concentration model. It is shown that, AQDS, simulating the organic compound in the soil, inhibits hydrogen permeation by decreasing the sub-surface hydrogen concentration, while sulfide promotes hydrogen permeation by inhibiting the hydrogen recombination and thus increasing the sub-surface hydrogen concentration. The steel specimen is more susceptible to stress corrosion cracking in the soil solution with a higher sub-surface hydrogen concentration, indicating that hydrogen is involved in near-neutral pH SCC in pipelines. It is suggested that hydrogen promotes the cracking of the steel, accompanying with the anodic dissolution on the crack sides and at the crack tip.     

Transport interests and environmental regimes: The Baltic Sea transit of Russian oil exports

In the environmentally exposed Baltic Sea, a prolonged confrontation has set the transport interests of Russian crude oil against environmental interests, promoted by Russia's neighbours. During the 1990s all the Baltic littoral states – including Russia – collaborated well on marine environmental issues. When Russian oil exports accelerated after 1999, this environmental understanding broke down. Russian interests shifted as its oil income suddenly rose drastically. The confrontation peaked over a proposal to make the entire Baltic Sea into a particularly sensitive sea area (PSSA) under the International Maritime Organization (IMO). The proposal was adopted by the IMO in spite of Russian objections. The article shows how environmental interests trump transport interests in a manner that may not be sustainable. The case illustrates the need for environmental collaboration to be flexible in the face of shifting constellations of competing interests.     

The exploitation of Norwegian oil and gas

In this article Henrik Ager-Hanssen reviews Norway's experience of developing its oil and gas resources in the North Sea. His emphasis is on the way regulatory policies have changed since drilling started in 1966. Trends in exploration activity and investment are outlined and the impact of current production levels on Norway's GDP are examined. The effects of possible future production levels are also considered. Finally, the author discusses infrastructure problems and the prospects for further development.     

Effect of hydrogen addition on the route preference in natural gas flow in regular,horizontal T-junctions

During the transport of natural gas through pipelines small amounts of condensate can be formed due to temperature and pressure changes. If this natural gas/condensate flow arrives at a regular, sharp-edged T-junction in the pipeline system an interesting phenomenon may be observed i.e. unequal phase splitting of gas and condensate. In this paper its has been shown that the addition of hydrogen into a natural gas stream results in a different splitting behaviour in comparison with the natural gas flow without hydrogen addition.     

A review of the oil and gas sector in Kazakhstan

Kazakhstan is endowed with significant oil and gas resources and is expected to become one of the world's top 10 oil producers within the next decade. The high cost of doing business in the country, however, means that Kazakhstan will need to improve its institutional framework to successfully compete for Western investment. A large degree of risk and uncertainty continues to plague the oil and gas sector as the government makes significant changes to the petroleum tax legislation and takes an aggressive approach in “rebalancing” contractual arrangements with industry. High levels of bureaucracy, regulatory burden, and corruption persist, and economic factors appear to be subordinated increasingly to geopolitical objectives aimed to strengthen relationships with China and Russia. The rapid pace of change and the high degree of uncertainty present significant challenges and risk to foreign investment. The purpose of this paper is to review the oil and gas sector in Kazakhstan and highlight recent developments in the petroleum legislation, business climate and government policy.     

燃气轮机压缩机组在西气东输管道上的应用

燃气轮机压缩机组在西气东输管道上获得了成功应用,积累了一定的经验,对大功率轻型燃气轮机驱动压缩机在管道输气上的推广可起到一定的借鉴作用.     

The production of crude oil and natural gas

This paper is directed at examining the impact of changing prices on the level of production of crude oil and natural gas in the United States. By using a cross-correlation test for unidirectional causality it is clearly demonstrated that, for both crude oil and natural gas, domestic production is affected by changing prices. The implications are clear. The decontrol of the price of crude oil and the deregulation of natural gas prices will lead to additional production in the near term.     

The taxation of UK oil and gas production: Why the windfalls got away

Starting with evidence that United Kingdom Continental Shelf oil and gas companies have benefitted very disproportionately from the recent period of extraordinarily high oil prices, this paper traces the history of this weakness in the UK’s petroleum fiscal regime. Evidence is provided that the progressive relaxations in the UK’s petroleum fiscal regime in 1983, 1987–1988 and 1993 were: largely unnecessary to stimulate the development of new, smaller, ‘marginal’ fields; misguided in their assumption that such fields were more costly to develop than earlier counterparts or larger contemporary fields; and impotent compared with the effects of oil price movements. The paper concludes with a conceptualisation which illuminates why these failures of policy were not just random: they emerged from the UK’s ‘non-proprietorial’ stance with respect to the country’s oil and gas resources, a stance which assumes responsibility for oil company profitability and vainly tries to counter market forces at the expense of government revenues.     

The role of non conventional oil in the attenuation of peak oil

In this paper, the possible substitution of conventional with non conventional oil is studied using system dynamics models. The model proposed in this paper is based on geological, economic and technological aspects, and it fits approximately the behaviour observed by Hubbert. A first validation of the model has been made with the USA oil production data. These USA data show that there is a good coincidence between our model and the reality. This model has been expanded in order to include the substitution of the conventional oil with the non conventional one for the World. Two models with different ways to treat the contribution of non conventional oil have been developed and tested: a base model (business as usual), which extrapolates the last two decades’ growth of this type of oil into the future, and a model that explores how much non conventional oil would be needed in order to avoid a peak and decrease in the global non renewable fuel production. The results show that, even under some hypotheses that we consider optimistic, the attenuation of the peak oil decline requires more than 10% of sustained growth of non conventional oil production over at least the next two decades.     

The role of oil prices in the forecasts of South African interest rates: A Bayesian approach

This paper considers whether the use of real oil price data can improve upon the forecasts for the nominal interest rate in South Africa. We employ Bayesian vector autoregressive models that make use of various measures of oil prices and compare the forecasting results of these models with those that do not make use of this data. The real oil price data is also disaggregated into positive and negative components to establish whether this would improve upon the forecasting performance of the model. The full dataset includes quarterly measures of output, consumer prices, exchange rates, interest rates and oil prices, where the initial in-sample period extends from 1979q1 to 1997q4. We then perform recursive estimations and one- to eight-step ahead forecasts over the out-of-sample period 1998q1 to 2014q4. The results suggest that the models that include information relating to oil prices outperform the model that does not include this information, when comparing their out-of-sample properties. In addition, the model with the positive component of oil price tends to perform better than other models over the short to medium horizons. Then lastly, the model that includes both the positive and negative components of the oil price, provides superior forecasts over longer horizons, where the improvement is large enough to ensure that it is the best forecasting model on average. Hence, not only do real oil prices matter when forecasting interest rates, but the use of disaggregate oil price data may facilitate additional improvements.     

The potential impacts of grid-connected distributed generation and how to address them: A review of technical and non-technical factors

Distributed generation is being deployed at increasing levels of penetration on electricity grids worldwide. It can have positive impacts on the network, but also negative impacts if integration is not properly managed. This is especially true of photovoltaics, in part because it's output fluctuates significantly and in part because it is being rapidly deployed in many countries. Potential positive impacts on grid operation can include reduced network flows and hence reduced losses and voltage drops. Potential negative impacts at high penetrations include voltage fluctuations, voltage rise and reverse power flow, power fluctuations, power factor changes, frequency regulation and harmonics, unintentional islanding, fault currents and grounding issues. This paper firstly reviews each of these impacts in detail, along with the current technical approaches available to address them. The second section of this paper discusses key non-technical factors, such as appropriate policies and institutional frameworks, which are essential to effectively coordinate the development and deployment of the different technical solutions most appropriate for particular jurisdictions. These frameworks will be different for different jurisdictions, and so no single approach will be appropriate worldwide.     

热媒炉加热技术在河口采油厂集输首站的应用

通过对热媒炉关键技术的分析和热媒炉应用前后的能耗试验对比 ,对热媒炉的应用效果进行评价     

Study on the stratification of the blended gas in the pipeline with hydrogen into natural gas

When blending hydrogen into existing natural gas pipelines, the non-uniform concentration distribution caused by the density difference between hydrogen and natural gas will result in the fluctuations of local hydrogen partial pressure, which may exceed the set one, leading to pipeline failure, leakage, measurement error, and terminal appliance. To solve the problem, the H₂–CH₄ stratification in the horizontal and undulated pipe was investigated experimentally and with numerical simulations. The results show that in the gas stagnant situation, hydrogen-methane blending process will cause an obvious stratification phenomenon. The relations between the elevation, pressure, hydrogen fraction, etc., and the gas stratification are figured out. Moreover, even when the blended gas flows at a low rate, the hydrogen-caused stratification should also be considered. Thereafter, the blended gas should be controlled into a situation with low pressure and high speed, which could help to set the pressure, speed, the fraction of H₂.