Better reservoir knowledge and increasingly sensitive technologies are making the production of unconventional natural gas economically viable and more efficient. This efficiency is bringing tight gas, coal-bed methane, and shale gas into the reach of more companies around the world. Especially, natural gas production from hydrocarbon rich shale formations, known as “shale gas”, is one of the most rapidly expanding trends in onshore domestic oil and gas exploration and production in the United States today. In some areas, this has included bringing drilling and production to regions that have seen little or no activity in the past. The lower 48 states have a wide distribution of highly organic shale containing vast resources of natural gas. This potential for production in the known onshore shale basins, coupled with other unconventional gas plays, is predicted to contribute significantly to the U.S.'s domestic energy outlook. No commercial shale-gas projects currently exist outside the U.S. and Australia, but work continues to identify both new shale-gas reservoirs and to add incremental shale-gas production in existing reservoirs.
Improvements in horizontal drilling combined with recent advancement in hydraulic fracturing techniques have resulted in the production of natural gas from shale formation, being one of the fastest growing segments in the United States (U.S.) oil and gas industry today. The shale gas production boom is transforming the energy market place, where the U.S. was expecting increased volume of imported Liquefied Natural Gas (LNG) to meet its domestic natural gas demand five to six years ago, is now looking forward to exporting LNG produced from the domestic gas in less than five to six years. In addition, it is also expecting growth in a wide range of chemical manufacturing industries relying on the use of low cost natural gas and its co-products. This paper provides a general description for the shale gas with recent advancement in production techniques. The paper identifies U.S. shale gas resources and the expected increase in gas production which has revolutionized and transformed the U.S. energy picture. The paper also provides recently identified worldwide shale gas resources that can be exploited.
The growth in shale gas production will also spur the growth in the associated infrastructure including gas purification or treatment facilities installation requirement for the removal of contaminants from the gas making it suitable for the end use. The paper provides a description of the available technologies that are generally utilized in gas treatment or purification of shale gas. The paper further describes the extraction of Natural Gas Liquids (NGL), or co-products of natural gas, consisting of ethane, propane, butane and natural gasoline (or light naphtha) that provides a low cost feedstock to downstream chemical production reducing the dependency on the import of foreign oil. The increased production of ethane from the NGL will have a significant positive economic impact and added value as a chemical precursor in transforming ethane to ethylene production at a lower cost. Over the last five years, the advancement in the shale gas production techniques has not only transformed the energy industry in the U.S. but also has a potential to change the global energy picture in the future.
City gas, which is mainly made from natural gas, has been widely recognized as clean fuel, and its demand is getting higher year by year in Japan. The natural gas is imported in the form of LNG from varied countries. The calorific value of the imported natural gas is usually lower than the Japanese city gas, therefore, gas companies adjust the calorific value of send-out city gas to the regulated value by adding LPG to the natural gas during the process of city gas production. We have developed a new, state-of-the-art, calorific value adjusting system, which operates in wide flow-rate range, more than four (4) times wider than a conventional system does. We report the outline of the newly developed system and its performance confirmed through a pilot-scale test, along with a short description of a typical process of city gas production and conventional methods of calorific value adjustment.
In the City of Yokohama, countermeasures against global warming have already been taken in a variety of forms, and technologies have been developed for the effective use of digestion gas which is a valuable energy generated from sewage works. As a result of our research carried out in 2005, digestion gas was refined to a high quality level of methane concentration not less than 95%. Then, in the equipment endurance tests performed as our researches in 2006 and 2007, the stability and infrequent maintainability of the equipment were confirmed as well as the quality of the digestion gas refined in long and continuous refining processes. The refined quality-enhanced digestion gas is expected to be effectively used as a substitute fuel to the city gas, however its substitutability has not been evaluated yet. In this research its combustion performance when mixed with the city gas, the limit values of the mixture ratio, and the property of the exhaust were examined and it was clarified that the digestion gas can serve as an excellent substitute fuel.
The internal combustion engines are required to use various fuels, fuels from biomass, shale gas and etc. to reduce the dependence on petroleum resources and to ensure enough energy. The composition of such fuels varies and its energy density is lower than traditional fuels used in engines. The author has been studying to use such fuels in stable and higher thermal efficiency from the view point of the engine control, advanced combustion technology and multi-fuel combustion with traditional fuels. This paper introduces such activities. The engine control system of a conventional spark ignition engine to use the gas fuels from biomass, its composition vary during engine operating, has been developed. The control system can set an optimum pre-mixture condition and an ignition timing for the fuels, which realizes a stable and high-thermal-efficiency operation automatically. To realize higher thermal efficiency, applicability of such fuels to an HCCI engine, ignition and combustion characteristics were investigated in an HCCI engine. It is clarified that HCCI combustion is available for such fuels and the ratio of H2 to CO2 in the fuels is useful to predict the combustion speed. The gas fuels are also applied to a diesel engine and the effect of H2 of gas fuels on ignition and combustion was investigated. Higher H2 content gas fuels realize higher thermal efficiency and stable combustion even if the amount of injected diesel fuel is small.
Intrinsic features of micro-scale flames are presented by surveying the vast previous and on-going works owing to its flame structure, and potential future and academic impact brought by micro-scale flames are summarized accordingly. The role of (micro) burner is pronounced when the flame size is minimized and variety of unique features, including excess enthalpy combustion, thus appear to improve the stability. Within the miniaturized flame, the major transport process is mainly dominated by diffusion so that the limiting micro-scale flames tend to be “spherical” irrespective of the flame type (both premixed and non-premixed flame). At the small-scale limit, the concept of flame sheet model (i.e., zero-thickness of the flame zone) is no longer valid, rather, the flame thickness becomes the same order to the characteristic length of transport. In this way, the micro-scale flame can be one of fundamental tools to investigate the basic nature of the flame. In order to clarify the unresolved issues related on the micro-scale flames, past works are briefly categorized and future challenges to be done with our best knowledge are also presented. Furthermore, potential of “new” research category driven by micro-scale flame study, named “high-Knudsen number reacting flow”, is additionally introduced. Due to the fact that there is missinglink to diagnose such small-scale flames directly, interdisciplinary cooperation with researchers in other fields (likely, micromachine, nano-scale technology) is highly encouraged.
The ignition timing of homogeneous charge compression ignition (HCCI) combustion engines is the important factor which should be controlled. In this study, the influences of the adding reaction intermediates to auto-ignition delay time were evaluated, by using a constant volume combustion simulation with detailed chemical reaction models of n-heptane and isooctane. The influences were evaluated for the initial temperature 600K-1050K and φ =0.3, 0.5 and 1.0, for n-heptaneair mixture and isooctane-air mixture. For both mixtures, the lower the initial temperature becomes, the larger the effect of additives on the ignition promotion becomes. Especially in the temperature range that is lower enough than negative temperature coefficient region, this effect becomes maximum. In addition, this feature is remarkable in lean mixture. Therefore, it is appropriate to supply additives at the temperature which is dominated by low temperature oxidation reaction, in order to control the auto-ignition timing of HCCI combustion.
In order to ignite fuel spray directly by a laser beam, it is necessary to investigate the characteristics of laserinduced breakdown ignition and generation of plasma as ignition sources in fuel spray. This study conducted experiments of laser-induced breakdown ignition in an ethanol spray and laser-induced breakdown in water mists by using the third harmonic of the Q-switched Nd:YAG laser. Photographs of the flame and the plasma were taken and laser beam energy for laser-induced breakdown was measured. The results of laser-induced breakdown ignition experiments show that the laserinduced breakdown ignition in a fuel spray was possible even at low incident energies that the laser-induced breakdown did not occur in air. The results of laser-induced breakdown experiments show that plasma was generated at the focal point in air, on the other hand, plasma was generated at multi-points in water mist. And the laser-induced breakdown occurred at much lower incident energy than that in air. The probability of breakdown occurrence increased with the incident energy and showed higher value at higher number density of water droplet.
The effect of the sintering characteristics of silica and titania particles on surface modification was investigated experimentally. The turbulent premixed burner, in which hexamethyl disiloxane (HMDS) or titanium tetraisopropoxide (TTIP) diluted with isopropyl alcohol (IPA) was sprayed, were used to feed silica or titania particles on the base material. According to the observation by SEM, the silica particles were agglomerates of small primary particles, whereas the titania particles had spherical shape under the same burner condition. Additionally, the coverage ratio of silica was larger than that of titania. The difference in the shape of those particles was due to the difference in the characteristic sintering time between silica and titania; the characteristic sintering time of titania was smaller than that of silica by 2-4 orders of magnitude. The result of the adhesive strength test showed that the adhesive strength was enhanced by 3-4 times at the maximum with HMDS. However, the excess surface particles after surface was saturated reduced the strength, therefore, there was an optimal condition for the spray time and the spray mass concentration. With TTIP, the adhesive strength was not so enhanced compared with HMDS, which was due to the spherical shape of titania particles that resulted in poor absorption on the base.