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70 巻 , 4 号
選択された号の論文の8件中1~8を表示しています
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平成17年度春季講演会特別講演
講演
  • 田中 浩一郎
    70 巻 (2005) 4 号 p. 287-293
    公開日: 2007/06/01
    ジャーナル フリー
    The events and developments in the Middle East over the past 30 years could be classified into three categories: a) events that are more or less of a domestic nature and confined to a single state in the region, b) developments that are mostly influenced by and imported from the surrounding environment to a certain country, and c) incidents that emanate from a regional state with a magnitude that would alter the then existing framework and norms of the international community.
    Although it is unlikely that it would bring about changes that could jolter the world, the Middle East in year 2005 is expecting quite a few number of elections and reforms: ranging from Iraq's interim assembly election and ending, probably, with another election in December that would elect a new and full-fledged Iraqi government.
    Even with the strong support and commitment by the developed countries to promote democracy in this region under the banner of the so-called Greater Middle East and North Africa Initiative, each and every election would naturally face their own problems, either politically or procedurally. Yet, the insistence and substantial involvement of the US as the only super power would be vital to the entire process.
    For those in the region who have hoped for democratic reforms to prevail, the perception of the mass vis-à-vis the US is a critical factor for their success. As long as the US is perceived as, by one reason or another, biased, ill minded, and acting on unilateralism and double standards, the advocators for democracy in the region would be in jeopardy.
    Revisiting the initial point, hypothetically when the US would move in to launch a ‘surgical’ strike against Iran, based on their assumption that the latter is covertly developing nuclear weapons, with the kind of material support that they have in hand today, the door would be left open to another interpretation of preemptive measures.
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  • 鎌倉 上
    70 巻 (2005) 4 号 p. 294-304
    公開日: 2007/06/01
    ジャーナル フリー
    Petroleum prices led by Crude oil prices have risen dramatically since the end of 2003 and have maintained a higher price range than what had previously been considered normal. The reason for current high prices cannot be explained by simple short-term fundamentals such as supply and demand balance, and inventory levels. However, they can be explained by the perception of future fundamentals instead. The market believes that world oil demand will be increasing steadily, notably from China and USA, while the supply side appears constrained. There is no additional production capacity left in OPEC and refineries are running at their full capacity to satisfy current oil demand. The Market is not looking at present fundamentals but future fundamentals, and this has lifted oil prices to an unexpectedly high level. Clear evidence of this perception is the rising forward curve. Previously, it was believed that long-term Crude oil price would remain at a level of 20's per barrel, and looking at the forward curve in the past, the forward price always converged to a level of around 20 per barrel. However, the current forward price converges to a level above $50 per barrel, which implies people consider the oil market price structure has greatly shifted upward. As long as the current market presupposes a continued firm demand increase versus a fragile supply situation, it is highly likely that oil prices will be staying at the high level as we are seeing now.
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  • 平 朝彦
    70 巻 (2005) 4 号 p. 305-314
    公開日: 2007/06/01
    ジャーナル フリー
    The plan for building a new scientific deep-sea drilling vessel in Japan started more than 10 years ago. JAMSTEC (Japan Agency for Marine-Earth Science and Technology) took leadership for this project and after numerous domestic and international meetings and workshops, the construction started April, 2001 and the launching ceremony was conducted January, 2002 at Tamano Shipyard of Mitsui Shipbuilding Co.. Then the ship moved to Nagasaki for further outfitting and is under the final phase of commissioning for its various equipments.
    Chikyu was designed to drill deep, deeper than anybody has done before in the deep sea floor. The initial target was set to drill 7,000m from 2,500m-deep seafloor and in the second phase it tried to drill 7,000m from 4,000m-deep seafloor. In order to ensure borehole stability and cleaning of rock cuttings, heavy mud circulation has to be maintained from the ship to the front end of drilling bit. Deployment of riser pipes that enable the confined circulation of heavy mud is the key technology of Chikyu. The ship is required to stay stationary for a long time at sea against wind, wave and current. This stability is achieved by installation of computer-controlled powerful six thrusters with unique ability of 360 degrees screw-axis rotation. Robotic and automated drill pipe handling system ensures safe working environment.
    Chikyu houses wonderful scientific research facilities. Four-storied laboratory space with array of advanced equipments welcomes 50 scientists and technical support staff. With synergy of state-of-the-art technology and enthusiasm of researchers and engineers, Chikyu challenges to the depth where deep unexplored biosphere exists, the mantle rocks gradually move, strain energy for mega-earthquake responsible for huge tsunami is accumulated and hidden records of the past history of the Earth are archived.
    After the delivery in July this year, the Center for Deep Earth Exploration of JAMSTEC will be responsible for the operation of the ship. Current plan is after two years of the test and training phase mostly at the offshore of Northeastern Japan, Chikyu will be introduced to IODP (Integrated Ocean Drilling Program) in late 2007. The voyage of Chikyu, seeking for a new frontier of science, technology and international collaboration is about to begin.
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論文
  • 菅井 裕一, 木下 睦, 湯本 徹也, 榎本 兵治, 洪 承燮, 藤原 和弘, 大野 健二
    70 巻 (2005) 4 号 p. 315-327
    公開日: 2007/06/01
    ジャーナル フリー
    Microbial EOR (MEOR) field test1∼4) was carried out in Fuyu oilfield, China. In this field test, Enterobacter sp. CJF-0027) which produced insoluble polymer was injected with nutrient, and oil production increased more than twice in volume because the high permeable zones were plugged with the polymer, and the water channeling was reduced8,9). Our research group carried out experimental studies to analyze the mechanisms of profile modification by the polymer produced by CJF-002.
    Firstly, 10m one-dimensional reservoir model was used for analyzing the polymer production behavior of CJF-002. CJF-002 was injected with nutrient and incubated. After the incubation, water was injected to observe the pressure of every 1m-point. As a result, high differential pressure was observed at the section of 0-1m and 3-4m. That is, CJF-002 produced the polymer at these section more actively. Moreover, it was suggested that a mixture of culture solution and brine improved pH of culture solution, and this improvement reactivated the polymer production of CJF-002 at the middle section (3-4m) and lower section.
    Secondly, network model was used for analyzing the effect of the polymer on profile modification. This model consisted of three 4m-low permeable sand-packs and one 4m-high permeable sand-pack. These sand-packs were reticulately jointed together at every 1m-point. CJF-002 was injected with nutrient from the central inlet and synthetic brine was injected from the other two inlets. Absolute permeability and flow rate of each section were calculated from the pressure observed at every jointing point. As a result, CJF-002 produced a significant amount of polymer in all the high permeable hose and the permeability of high permeable hoses decreased to approximately 1/2 of original permeability. Consequently, the flow rate of high permeable hoses decreased and that of low permeable hoses increased. It showed that the polymer produced by CJF-002 was effective on the profile modification.
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  • 巴 保義, 清水 誠
    70 巻 (2005) 4 号 p. 328-332
    公開日: 2007/06/01
    ジャーナル フリー
    Localized corrosion was found on inner surfaces of 13 %Cr steel tubing at shallow depths in deep, hot corrosive Minami-Nagaoka gas wells. Judging from the high penetration rates of corrosion pits, factors other than high temperature and carbon dioxide (CO2) are expected to exist. The chemical analyses on produced fluids revealed that acetic acid of 250∼300 ppm existed in the produced condensed water. Laboratory corrosion test results showed that acetic acid in the condensed water saturated with CO2 markedly affected the passivity of 13 %Cr steel due to low pH. The existence of acetic acid can be a cause of the localized corrosion of 13 %Cr steel tubing in Minami-Nagaoka wells.
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  • 長縄 成実
    70 巻 (2005) 4 号 p. 333-346
    公開日: 2007/06/01
    ジャーナル フリー
    It has been reported in previous studies that dominant peaks of a power spectrum for roller cone bit axial vibration moved to higher frequencies as the bit tooth wear progressed. This experimental result implies that monitoring and analyzing roller cone bit vibration could be a new real-time diagnosis method of downhole bit wear conditions.
    In this paper, dynamics of roller cone bit axial vibration was modeled to make a quantitative evaluation of bit vibration characteristics. The model includes kinematics of roller cone bit motion, and a model for bit-tooth/rock interaction in consideration of worn tooth geometry and inclination of tooth penetration. Sequentially solving the equation of motion with increments of cone rotation angles under some constraints on cone rotations, time history of axial bit vibration was simulated.
    The developed model was validated by comparing the power spectral densities for simulated time histories of bit displacement and weight on bit with experimental results in full-scale drilling tests. Simulation study revealed that the characteristics of roller cone bit axial vibration was very sensitive to a small variation of cone rotation speed, and that bit tooth tracking on bottomhole craters could constrain the cone rotation speeds depending on the situation.
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報告
  • 大澤 正博, Lukas U. Wihardjo, 三石 裕之, 村本 宏司, 石山 義明
    70 巻 (2005) 4 号 p. 347-357
    公開日: 2007/06/01
    ジャーナル フリー
    METI Sado Nansei Oki Wells, drilled in the deep water Toyama Trough in the Sea of Japan offshore Niigata Prefecture, Japan, encountered the Pliocene Shiiya Formation that contains 15 meters of oil column. Sandstones of the Shiiya Formation are turbidite origin and with varieties of lithology. Fine grained and poorly sorted lithic arenite is dominated in the upper part, and fine grained and poorly sorted lithic wacke is dominated in the lower part of the formation. Due to fine grained and poorly sorted nature, and tuffaceous or muddy matrix, pore size in the wacke varies substantially.
    Combinable Nuclear Magnetic Resonance (CMR) logging, which measures three different sizes of porosities, namely clay bound water porosity (pore occupied by clay-bound water), capillary bound fluid porosity (pore occupied by capillary-bound fluid) and free fluid porosity (pore in the center of medium to large size pores where fluid can flow), is very useful to characterize the sandstone in the Shiiya Formation.
    Complicated lithology of the Shiiya sandstone renders the formation evaluation a challenging task at METI Sodo Nansei Oki S Well. The resistivity of the oil reservoir wacke interval is very low, which is almost same with the arenite interval with no oil shows at all.
    Formation evaluation using CMR (CMR ELAN) revealed that the oil reservoir wacke contains up to 15% of capillary bound fluid porosity while free fluid porosity is 8∼14% at best. Although oil saturation is not high enough for the total porosity, the effective oil saturation is quite high if all oil is assumed to be confined in the free fluid pore. High oil saturation within free fluid pore with a large amount of clay bound water and capillary bound fluid is a reasonable explanation for the oil bearing but very low resistive wacke interval.
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用語解説
  • 伊藤 慎
    70 巻 (2005) 4 号 p. 358-369
    公開日: 2007/06/01
    ジャーナル フリー
    In this commentary article, architecture, component lithofacies, and bounding surface features of forced-regressive deposits are discussed in terms of a four-fold classification scheme of sequence stratigraphy in siliciclastic successions. Forced-regressive deposits are interpreted to represent a falling-stage systems tract, which develops mainly in a shallow marine environment, and to be equivalent chronostratigraphically to basin-floor-fan and slope-fan deposits in a deep-water environment. The standard sequence-stratigraphic model classifies shelf-margin deltas as a component of the lowstand wedge, which is interpreted to develop over the basin-floor-fan and slope-fan deposits. However, shelf-margin deltas, in general, consist of downstepping forced-regressive and overlying progradational and aggradational deposits, which can be assigned, respectively, to falling-stage and lowstand systems tracts of the four-fold classification scheme. Recognition of forced-regressive deposits depends on appropriate definition of datum for the correlation of stratigraphic successions and on detailed process-oriented lithofacies analysis that is crucial for the identification of depositional events responding to a relative sea-level fall. Thus, practical approaches of facies analysis and sequence-stratigrapy should constantly be upgraded for the better understand of formative processes, 3D geometry, distribution patterns, and heterogeneity of forced-regressive deposits.
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