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67 巻 , 4 号
選択された号の論文の5件中1~5を表示しています
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  • 大沢 千比呂
    67 巻 (2002) 4 号 p. 343-351
    公開日: 2008/03/27
    ジャーナル フリー
    The city gas companies in Japan sell 25, 400 million-cubic meter gas per year to 26million consumers. The amount of sale has increased favorably into 46% in the last ten years.Although there are more than 230 city gas companies in Japan, four companies with more than 1 million consumers occupy 80% of the amount of sale, and 70% of the consumers.
    The share of high calory gas has become 87% of the whole, and concentration to the highcalory gas is progressing. Local gas companies are tackling natural gas conversion and high caloryquantification which are big subjects with might and main.
    Nine gas companies in Akita supply city gas to 120, 000 consumers by using natural gasproduced in the prefecture. The gas business in the prefecture has reached a plateau in the numberof consumers and the amount of sale, because of reduction in population, deterioration of economicconditions, and intensified competition with other fuel.
    This time, I will talk about the outline of the city gas business in Japan, and the problemwhich the local city gas companies are facing. Then, I will mention the change of the environmentsurrounding local city gas companies, and the correspondence to such change.
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  • 岩間 剛一
    67 巻 (2002) 4 号 p. 352-358
    公開日: 2008/03/27
    ジャーナル フリー
    Now, Japanese oil exploration companies face an unprecedented crisis. To begin with the abolishment of Japan National Oil Corporation (JNOC) which played the most important role in the oil exploration activities in foreign countries, there are many problems such as the lost of oil development interest in Saudi Arabia and the accumulated loss of some Japanese oil companies. On the other hand, the dependence on Middle East in the field of oil import of Japan is approaching the critical level i.e. more than 85%. The act of abolishment of Japan National Oil Corporation could be regarded as the model case of the reformation of a public corporation in Japan.
    The main functions of JNOC include (1) to provide oil exploration activities with risk money, (2) research and development in the field of oil exploration, (3) to manage the national petroleum reserve. And, these important functions will be succeed to a newly established independent administrative entity, which means the Government recognizes the importance of national aid in oil exploration.
    Of course, there are some problems to be solved in the past JNOC's activities. Since the establishment of JNOC 34 years ago, it has lent and invested about 2 trillion Japanese Yen and has had the accumulated loss of 0.9 trillion Yen. This is mainly why the Japanese oil exploration policy was unsuccessful in strengthening the Japanese oil companies and unexpected changes of international economy such as the rapid appreciation of Japanese Yen occurred.
    In the 21st century, in order to compete equally with Western Super Oil Majors which have the advantage of capital and technology, it is to some extent essential for the Government to assist the Japanese oil companies. Japan, as the second largest oil consuming country, is responsible for the development of upstream business which gives us a large amount of benefit. In addition, it is necessary for us to establish a core oil exploration company including electric companies, gas companies and sogoshousha together with the Governmental aid, because big projects such as the developments of oil and gas fields amount to 1 trillion yen.
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  • 柳沢 幸夫, 須藤 斎
    67 巻 (2002) 4 号 p. 359-368
    公開日: 2008/03/27
    ジャーナル フリー
    Marine diatom biostratigraphy is established for the upper Miocene to upper Pliocene sequence (the Shigekurayama, Taira and Minagawa Formations) in the Shitada area, Niigata Prefecture, central Japan. The Shigekurayama Formation is composed of dacite lava and pyroclastic rocks with large mudstone blocks which contain diatom assemblages correlative with the diatom zones NPD 5C to NPD 6B. The age of Shigekurayama Formation is inferred to be 8.0-8.4Ma on the basis of diatom ages of the underlying Minamiimogawa and overlying Taira Formations. The Taira Formation is divided into the lower and upper parts by a late Miocene unconformity ranging from 7.2Ma to 5.4Ma in age. The lower Taira Formation is correlated to the diatom zones NPD 6B to NPD 7A, whereas the upper Taira Formation contains diatoms correlative with the zone NPD 7Bb. The Minagawa Formation yields no age-diagnostic diatoms, but may be late Pliocene in age based on tephrochronology.
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  • 巴 保義, 清水 誠, 金田 英伯
    67 巻 (2002) 4 号 p. 369-378
    公開日: 2008/03/27
    ジャーナル フリー
    CO2を吸収したアルカノールアミン溶液中の炭素鋼試験片の腐食速度を,重量減法と分極抵抗法により測定した。10-2Mより低濃度のアミン溶液中でし高温-CO2環境と同様に,保護性のFeCO3スケールの生成により炭素鋼の腐食は抑制された。試験に供したアミン類は10-2~2Mの濃度範囲でCO2による腐食を抑制した。3Mより高濃度において,第一アルカノールアミン類と第三アルカノールアミン類は炭素鋼の腐食に対して顕著に異なる影響を与えた。炭素鋼の腐食速度は第一アミン濃度の増加とともに上昇した。これに対し,第三アミン溶液の場合には,保護性のFeCO3スケールの生成により,6Mという高濃度においても低い腐食速度であった。
    第三アミン類は水の存在下でCO2をHCO3-と。て吸収する。いっぽう,第一アミン類は2通りの方法でCO2を吸収する。1つは第三アミン類と同様にHCO3-としての吸収であり,もういっぽうは,水の存在無しに直接的にCO2を吸収しアミン-カーバメイトを生成する方法である。
    アミン類がCO2を吸収することにより生成する化学種が,炭素鋼の腐食速度だけでしなく,腐食生成物の形態と保護性にも大きな影響を与える。
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  • 吉岡 克平
    67 巻 (2002) 4 号 p. 394-399
    公開日: 2008/03/27
    ジャーナル フリー
    The word kriging, which is a basic concept of geostatistics, was named from D. G. Krige, a South African mining engineer, who developed a new estimation method in the early 1950s. Georges Matheron, who was a French engineer and currently known as a creator of geostatistics, formalized Krige's innovative concepts in the early 1960s. It was the mid-to late 1980s that geostatistical techniques started to be used in the petroleum industry. The reasons why geostatistics has been spread so much in the petroleum industry are the three major features as follows, 1) Geostatistical techniques are mapping (or modeling) tools utilizing the spatial continuity of existing data. 2) They can estimate uncertainty from variance distribution. 3) They can integrate geology, geophysics, and engineering data.
    For example, kriging not only provides a spatial distribution but also estimate error-variance at any unknown data point. Kriged results are depended on a variogram model, which has been build from known data (e. g. well-log measurement). Cokriging, expanded from kriging, uses different kind of data. When porosity value should be estimated, the related acoustic data, such as seismic data, are combined. Sequential simulation (or cosimulation) techniques, based on kriging (or cokriging), can provide the equi-probable images more heterogeneous than kriged (or cokriged) results. They are now indispensable tools of reservoir characterization.
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