Nippon Oil Exploration Ltd. (NOEX), a subsidiary of Nippon Mitsubishi Oil Company, participates up-stream business in 11 countries with 20 oil and gas E & P projects, where NOEX has the role of operator in Malaysia, Vietnam, Australia and the United States. NOEX is involved in several gas projects in South East Asia, Australia and the United States. In general, gas field development could be commercialized on the condition that gas markets are large enough to commit long-term gas supply. Transportation method of produced gas from field sites to markets today is limited only to either pipeline or LNG tankers. These limitations restrict to make a profit in a short time, specially on these gas fields located in remote area from markets, even for bigger size of reserves. Most of NOEX gas development projects are being carried out by conventional methods, with the exception of newly discovered gas field in Australia, where early economical development is sought with the application of new technology. In this paper, five NOEX gas projects are introduced from the viewpoints of three different development types, such as pipeline, LNG and new technology. Yetagun gas field, which was discovered in 1992, offshore Andaman Sea in Myanmar, started gas production in May 2000 to export gas to Thailand through pipeline. Another gas pipeline project has been planned in Papua New Guinea to utilize oil fields' associated gas to Australian market. Gas fields in offshore Sarawak, Malaysia discovered in 1990 through 1994 are under development to feed source gas to MLNG-3 plant, which is also under construction in Bintulu, Sarawak. Planned start-up date of gas production is October 2003. Tangguh LNG project in Indonesia is also in progress, however, difficulties of finding new customers in saturated Asian gas market cause prolongation of project schedule. In May 2000, new gas reserves were discovered by drilling NOEX's exploration well Crux-1 in AC/P23 licensed area in Timor Sea, West Australia. Longer distance to the shore market and middle size of the reserves may prevent the early development of Crux gas field in case conventional approach is implemented. Application of Gas to Liquid (GTL) technology may be the most realistic alternative for Crux development under today's saturated LNG market, small domestic market and global environmental requirement. Under these circumstances, NOEX has started a feasibility study of GTL applicability to Crux gas field to make a profit as early as possible. Once GTL technology becomes viable both technically and economically, NOEX's strategy to gas resources would be changed to more aggressive direction.
GTL technology is one of the most promising technologies which makes it possible to convert natural gas to clean liquid fuels. They can be utilized for gasoline engine, diesel engine or fuel cell. GTL technology is composed of two or three steps: (1) Reforming of natural gas to syngas (CO+H2), (2) Conversion of syngas to liquid hydrocarbons (Fisher-Tropsch (F. T) Synthesis), or (3) Conversion of syngas to methanol and methanol to aromatics plus iso-paraffins (Methanol to Gasoline (MTG) Process). MTG process utilizes a special zeolite catalyst to convert methanol to gasoline at high temperatures, whose research octane number is about 93, and small amount of LPG. The total energy efficiency from natural gas to products is about 55%. This technology has been commercialized since 1986 in New Zealand with the scale of 15, 000 bpd. The F.T synthesis gives mainly straight chain paraffins and olefins with wide distribution of carbon number (C1_??_C100+). Products (C10_??_C20) are quite suitable material as diesel fuel, whichexhibits high cetane number (_??_70), low sulfur content (_??_0), low aromatics content (_??_0), andlow density (780g/1). These characters lead to the low emissions from diesel engine (soot, SOx, NOx and hydrocarbons). Two GTL (F. T) commercial phants have been operated since 1992 and 1993, which are developed by SASOL in South Africa and Shell in Malaysia, respectively. Lighter products (C5_??_C10) can be used as petrochemical feed stock or can be reformed to gasoline. Heavier products can be used as wax (after purification), lubricant (after isomerization) or diesel oil (after hydrocracking). Commercial GTL process has the cost competability when its scale correspond to the annual gas consumption of about 1 million ton. This means that the process can utilize the products from the gas field with rather small scale.
Recently, natural gas has been paid great attention as a major energy source in the next century due to its inherently better characteristics towards global and local environments than other fossil fuels. In order to enhance the use of natural gas, currently, numerous technologies in the area of GTL (Gas-To-Liquids), fuel cell technology and others are being prepared for commercial applications. However, even state-of-the-art technologies have many problems that might be obstacles for future commercial spread of the technology. As a potential candidate such innovative technology that can solve the above problems, ceramic membrane reactors for syngas or hydrogen generation from natural gas had been proposed in US, Europe and Japan. Teikoku Oil Co., Ltd. had investigated the potential and, as a result of the investigation, initiated the R & D program on ceramic membrane reactors in January, 1999. Some of the achievements by the on-going R & D program are presented.
Methane hydrate is attractive as a gas transport medium because it includes much amount of gas at relatively milder condition than conventional media. Four subjects, equilibrium conditions, formation/dissociation speed, gas amount included, and fluidity were investigated. It was indicated that those properties are controllable.
DME (Dimethyl Ether) is a clean and economical alternative fuel which can be produced from various resources as natural gas, coal or biomass through synthesis gas. The properties of DME are similar to those of LPG and it can be used for various fields; power generation fuel, transportation fuel, home fuel, etc. An innovative process of direct synthesis of DME from synthesis gas has been developed. Newly developed catalyst in a slurry phase reactor gave a high conversion and high selectivity of DME. Pilot scale plant (5 tons/day) testing has been successfully carried out since 1999 with the Japanese government support. A feasibility study of DME Fuel System, which includes production of DME from natural gas and its transportation to Japan, indicates that DME is competitive to conventional fuels.
Japan National Oil Corporation (JNOC) is preparing to construct national LPG stockpiling bases (Nanao, Ishikawa prefecture; Fukushima, Nagasaki prefecture; Namikata, Ehime prefecture; Kurashiki, Okayama prefecture) for achievement of a government LPG stockpile of 1.5 million tons by fiscal 2010. JNOC has also conducted a feasibility study at Kamisu site (Ibaraki prefecture). As stockpiling systems, on-ground tanks system and water-sealed underground tanks system will be adopted. Underground tanks system will be adopted at stockpiling bases in Namikata (450 thousand tons) and Kurashiki (400 thousand tons). Underground stockpiling facilities which are build by creating caverns and then sealing normal temperature LPG inside by means of groundwater pressure. This methods is used at many different bases in overseas because of it has a high level of safety, and is economical to construction and maintain. In this paper, outline of each project, principle and characteristic of underground cavern stockpiling method, and design of water sealing system are described.
The purpose of this report is to have a general view of the present status on research, development and demonstration of fuel cells in addition to their principle and characteristics. Among a few kinds of fuel cells, PAFC has almost reached at the semi-commercial stage, and large efforts have now been given for realizing the PAFC as cogeneration plant using the biogas from garbage and beer brewery process. MCFC is on the way of the demonstration stage with a large scale system under the ledership of NEDO and MITI in Japan. With respect to SOFC several organizations have been taking part in its research and development projects for the purpose of developing super-high efficient power system. PEFC is becoming more and more attractive in expectation of being especially realized as fuel cell propulsion system for electric vehicles and also as residential co-generation devices. A large number of companies have recently entered into the fields related to PEFC system development including fuel delivery infrastructure.
Technological innovation for the natural gas utilization and the increasing concern for the environment, especially the global warming, are major driving forces of the current increases in world-wide natural gas demand. In the first half of the 21st century, the role of natural gas will be more important than is now in the world energy market. Some Asian developing countries such as China and India, are now planning to import liquefied natural gas (LNG) or pipeline natural gas (PNG) into their domestic markets, and to promote their LNG/PNG usage. This paper addresses the key issues surrounding the potential expansion of the natural gas usage in Japan.
Minami-Kanto gas field yields natural gas dissolved in water from the formations consisting of alternating thin beds of sandstone and mudstone. As its remarkable feature, there are regions which show so-called Mobara type gas production behavior characterized by both increase of gas water ratio and rapid depletion of reservoir pressure. A series of laboratory experiments was carried out using X-ray CT scanner in order to investigate the fluid behavior in mudstone because most of the produced gas is considered to be supplied from very low permeable mudstones in this region. In each experiment, gas flow rate was measured with incremental drop of pore pressure, while the effective confining pressure was maintained so as to prevent the core from compaction. Our experiments showed that the existence of free gas in mudstone greatly contributed to the Mobara type gas production behavior, and that the mudstone beds might act as reservoirs for gas fields showing the Mobara type gas production behavior.
Appropriate modeling of naturally fractured reservoirs is one of the most important and challenging issues in reservoir characterization. In simulation, a dual porosity or dual permeability model is applied when fractures are well developed to form a fracture network. On the other hand, the single-continuum approach, where the fracture system is represented by effective permeability, is commonly used if fractures are discrete or disconnected. Focusing on the latter case, this paper proposes a semi-analytical technique to evaluate effective permeability for periodically or randomly fractured media including infinitely thin, infinite-conductivity fractures. The complex variable boundary element method is used to compute potential fields and streamlines in the two-dimensional space for discretely distributed fracture systems under the periodic boundary conditions. Effective permeability is evaluated first for discrete fracture systems of regular patterns to demonstrate the validity of the method and to examine the sensitivity of the effective permeability to the variations in the basic fracture parameters. With a constant total length of fractures, systems of varied fracture lengths show higher effective permeability than systems of uniform fracture length. 500 distributions of stochastic fractures are next generated to establish correlation between effective permeability and the fracture parameters, total length L, mean length m, and standard deviation of fracture length ?D. Sensitivity to the parameters shows that non-zero a increases effective permeability, that the incremental gain of effective permeability is proportional to L, and that the larger m, the larger effective permeability. The effective permeability tensors are also determined for oriented fractures. Analyses by non-parametric regression show that the diagonal elements, kxx and kyy, are highly affected by the angle between the oriented fractures and the pressure gradient, while the off-diagonal elements, kxy and kyx, are strongly affected by both the total length and the angle.