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55 巻, 3 号
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その2: 形成過程から見た比較鍋谷 淳, 宮田 雄一郎, 岩田 尊夫, 山村 恒夫1990 年 55 巻 3 号 p. 177-185
発行日: 1990年
公開日: 2008/03/27
ジャーナル フリーThe sediment load brought by rivers to lakes and seas is controlled by the climate, geology, and geography of the drainage basins. In most fine-grained deltas the density relationship between discharged river water and the recipient water body dictates that homopycnal-type inflows occur commonly in lacustrine deltas, and hypopycnal-type (buoyant) inflows in marine deltas. Since sea water has a higher cation content than lake water, the suspended load in marine rivermouths is rapidly flocculated and settled as delta sediments. This flocculation explains why large-scale deltas consisting of fine-grained sediments occur more commonly in marine rivermouths than in lacustrine rivermouths.
Lacustrine deltas are less subjected to tidal influences than are marine deltas. Therefore, estuarine morphologies which may occur in marine deltas are unlikely to be found in lacustrine deltas. Water-level changes are mainly controlled by tectonics of the receiving delta basins in lakes, and by eustatic sea-level changes in seas. Recent marine deltas, therefore, have highly uniform bottom ages corresponding to the climax age of the Holocene Jomon transgression or Frandrian transgression. In contrast, recent lacustrine deltas have various bottom ages. Gentle basin slopes may result in shallower water depths at the rivermouths, especially in larger-scale delta bodies. With increasing basin slope, wave and tide energies are increassed, resulting in small-scale delta bodies and in the characteristic continuity of sand bodies. Gentle basin slopes occur in epeirogenetic lake basins and on marine continental shelves. The other marine processes have basically the same effect on delta formation as processes in lakes.
Morphologies of delta bodies are determined not only by fluvial and marine (or lacustrine) processes, but also by the tectonics and geometry of the receiving delta basins.抄録全体を表示PDF形式でダウンロード (687K) -
秋林 智, 福田 道博, 山本 厳1990 年 55 巻 3 号 p. 186-197
発行日: 1990年
公開日: 2008/03/27
ジャーナル フリーA vertical two-dimensional model of mixed (free and forced) convection is developed for a geothermal system in which permeability varies continuously.
A formula for two-dimensional flow is derived for computing interblock permeabilities which varies more or less linearly between centers of finite difference blocks.
Using the above formula in the vertical two-dimensional model of mixed convection, the temperature and pressure distributions are estimated for cases where the variation in permeability is linear between centers of finite difference blocks.
Eventually, this model is applied to the Okuaizu geothermal field in Fukushima prefecture. Then, flow and temperature fields in the entire system consisting of fractured zones and impermeable zones are obtained.抄録全体を表示PDF形式でダウンロード (628K) -
中島 敬史, 大野木 龍之介1990 年 55 巻 3 号 p. 198-207
発行日: 1990年
公開日: 2008/03/27
ジャーナル フリーMost conventional soil-gas methods use instantaneous samples, in which the sample collected represents the soil-gas composition at the moment of collection. Short-term meteorological influences may yield noisy data. The K-V Fingerprint Technique couples time-integrated soil-gas collection with mass-spectrometric analysis and pattern recognition, and thus overcomes the problems inherent in most other gas geochemical methods.
Three surveys using the K-V Fingerprint Technique have been conducted in the Minami-Aga Oil Field Case Study (Niigata Prefecture, Japan) in 1986, 1987, and 1988. The results of the three surveys show an apical geochemical anomaly over the same area of the Minami-Aga Oil Field every year. The factor spectrum derived from factor analysis of the mass spectra shows that light aromatic hydrocarbons are responsible for the geochemical anomalies.
Furthermore, a few samples collected over the known producing area and samples of vapor-phase compounds present in equilibrium with some crude-oil samples were analyzed by GC-MS to verify the compositional relationship between surface soil gases and the oil in the reservoir.
Based on those analyzed data, it was concluded that hydrocarbon gases from the reservoir at 2, 300 meters reach the surface in less than 20 years.抄録全体を表示PDF形式でダウンロード (667K) -
山田 眞, 町原 勉1990 年 55 巻 3 号 p. 208-214
発行日: 1990年
公開日: 2008/03/27
ジャーナル フリーA rapid method for determination of organic carbon in carbonate rocks has been developed to replace the normal procedure in which carbonate samples are pretreated with hydrochloric acid to decompose carbonate minerals. The method involves dry combustion of organic material in an oxygen stream and subsequent measuring of carbon dioxide (CO2) generated.
Experimental data were obtained by changing combustion temperatures (450-900°C) and combustion time (5-15 minutes) using YANACO CHN-corder (model MT-5). Based on the difference of the decomposition rates between organic matter (coal and shale) and inorganic carbonates (calcium carbonate and dolomite), we have concluded that combustion conditions of 550°C for 15 minutes are appropriate for organic-carbon analysis of carbonate rocks. Amounts of sample needed for experiments are 10-100mg. More than 90% of the organic carbon can be detected directly under these conditions without any pretreatment of the sample, and the influence of inorganic carbon is less than 0.03% of the sample weight. This simplified method is also applicable for organic-carbon analysis of non-calcareous samples such as shales.抄録全体を表示PDF形式でダウンロード (478K) -
その1. ポリマー溶液の多孔質媒体内流動モデル増田 昌敬, 唐 克勤, 宮沢 政, 田中 彰一1990 年 55 巻 3 号 p. 215-225
発行日: 1990年
公開日: 2008/03/27
ジャーナル フリーAs polymer solution behaves as a shear-thinning viscoelastic fluid, its viscoelastic effects need to be considered in the analysis of polymer-flood performance. A new model including the viscoelastic effects was developed for predicting flow behaviors of polymer solution through porous media.
In model formulation, total pressure drop is assumed to be the sum of viscous and elastic terms for the flow of polymer solution in porous media. Non-Newtonian viscosity of the solution is modeled as the Ellis fluid. The Kozeny-Carman model is used as a physical model of porous media. A new equation is proposed to predict the elastic pressure drop induced by polymer elasticity. This equation correlates the ratio of elastic pressure drop and viscous one with the Deborah number by introducing geometric parameters of porous media (C, mc). The Darcy's equation is modified to predict the viscoelastic flow behavior, where Darcy viscosity is expressed to be the sum of viscous viscosity and elastic one.
Flow experiments of 200ppm polyacrylamide solution were done with glass-bead-packed cores. Calculated flow behaviors of polymer solution, based on the proposed model, were compared with the experimental data and found to be in good agreement.抄録全体を表示PDF形式でダウンロード (670K)
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