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63 巻 , 3 号
選択された号の論文の7件中1~7を表示しています
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  • 大久保 進
    63 巻 (1998) 3 号 p. 205-215
    公開日: 2008/03/27
    ジャーナル フリー
    Occurrences and microthermometric characteristics of hydrocarbon inclusions found in the MITI-Mishima well in Niigata Prefecture, Japan, have been studied and their implications are discussed. They occur locally in the lower part of the well, from the Miocene Lower Teradomari Formation through to the upper part of the Nanatani Formation, in which the main source rocks consist in the Niigata oil and gas fields.
    Occurrences and crystal shapes of quartz with hydrocarbon inclusions suggest that fractures were the main migration pathways of the hydrocarbons. Quartz crystals with hydrocarbon inclusions were found on extensional open fracture surfaces in cores. They also occur as euhedral or subhedral crystals in cuttings. Intergranular pore spaces in sandstone are rarely observed in this horizon. The occurences and crystal shapes of quartz indicate that they had precipitated in open spaces, and so the pathways of hydrocarbons mainly lie in the open-fractures of the source rock.
    The microthermometric characteristics of the inclusions suggest that the migrations of hydrocarbons occurred at least twice. The hydrocarbons in the inclusions from the MITI-Mishima well, commonly composed of vapor, liquid and bituminous solid, are classified into the vapor-homogenized type and the liquid-homogenized type. This is based on their behaviour when heated on the stage of the microscope. These two types of inclusions do not exist in the same grain, although they occur in the same range of depth in this well.
    The experiments on the estimation of the degree of thermal change of the hydrocarbon inclusions in a closed system, show that the homogenization temperature, which is initially 66.9°C, decreases to 45.9°C. This is after the inclusions have been heated to 370°C for 192 hours. Thus, the hydrocarbons in the inclusions are revealed to have cracked at this temperature.
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  • 三木 孝
    63 巻 (1998) 3 号 p. 216-220
    公開日: 2008/03/27
    ジャーナル フリー
    Cretaceous and Paleogene formations consisting of various kinds of sedimentary rocks are exposed in northern Kyushu, Japan. Their geological examination is doubtlessly necessary for future oil exploration activities in the region.
    From viewpoints of total organic carbon contents and types of organic matter in mudstones, the formations cannot be recommended generally as suitable source rocks for oil. Maturation studies of sediments suggest that the Cretaceous rocks are mostly post-matured and mudstone-rich parts of the Paleogene successions in some basins are matured. The present study shows that the more detailed research data should be accumulated not only from the land areas but also from the sea region off Kyushu for future oil generation studies.
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  • 土田 邦博, 牛 犇, 吉村 尚久, 大久保 進, 深澤 光
    63 巻 (1998) 3 号 p. 221-228
    公開日: 2008/03/27
    ジャーナル フリー
    The MITI exploratory test well “Tomikura” was drilled 6, 000m in depth by Japan National Oil Corporation. The geology of this well is mainly composed of the middle Miocene sedimentary rocks. These rocks are very hard, and have undergone high grade diagenesis. Illite/smectite interstratified minerals (I/S) are well known indicators of diagenetic and/or burial metamorphic grade. Increase of illite layers depends on burial depth.
    The experimental results show that the illite layers in I/S increase with increasing burial depth. The changes of I/S are divided into five steps as follows:
    I) slow conversion to illite layer with 20-30% I,
    II) rapid conversion from 20-30% I to 70% I,
    III) slow conversion with 70% I,
    IV) rapid conversion from 70% I to 80% I,
    V) slow conversion with 80% I.
    The rapid conversion zones (II and IV) are important in the structural changes of I/S interstratification. In “Transition zone 1” (1, 700-3, 000m in depth), randomly interstratified structure (R0) has converted to the regular structure with R1 by transition, containing 30-70% I. Conversion of R1 to R3 interstratification occured in “Transition zone 2” (3, 400-4, 000m in depth), containing 70-80% I.
    As a result of conversion of smectite to illite, the released water from the interlayers has had an influence on the interparticle condition. Log interpretations suggest that the water dehydrated from the interlayer of smectite has had an effect on the interparticle pore. Especially, dehydrated water in “Transition zone 1” is associated with the formation of the abnormal pressure zone.
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  • 楊 延国, 新堀 雄一, 千田 佶
    63 巻 (1998) 3 号 p. 229-238
    公開日: 2008/03/27
    ジャーナル フリー
    This study focuses on the efficient spread of nutrients for microbial enhanced oil recovery (MEOR), which in turn controls the growth rates of bacteria. By using a two-dimensional packed-bed with glass-beads, flooding and huff&puff experiments with and without a shut-in process were carried out in order to examine distribution of nutrients. KCl solution was applied to replicate nutrients. The experimental results by the solution injections into the horizontal bed or the vertical one, showed good agreements with the calculations of the two-dimensional mathematical model considering the convection, the mixing diffusion and the buoyancy force due to differences of the solution concentration. Effects of the shut-in period on distribution of nutrients were also investigated by using the mathematical model. The results displayed that the transport of the nutrient and its distribution depended clearly on the starting time of shut-in and the injection concentration of the nutrient.
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  • 山本 正伸, バッテルデン デレギン, オルツィヒシ プレイン, 渡部 芳夫, 武田 信從, 梶原 義照, 中嶋 輝允
    63 巻 (1998) 3 号 p. 239-250
    公開日: 2008/03/27
    ジャーナル フリー
    Elemental analyses, Fischer assay pyrolysis, Rock-Eval pyrolysis and biomarker analyses were conducted for twenty-six lacustrine oil shales from the Lower Cretaceous Dsunbayan Group, Mongolia.
    The Dsunbayan oil shales show large variations of organic carbon content (1.7-21.3wt%) and oil yield (0.3-11.8 wt%). A Rock-Eval pyrolysis shows that immature Type I kerogen dominates in these samples. Biomarker compositions show that major source organisms of the Dsunbayan oil shale were an autotrophic prokaryote such as a cyanobacterium, nonmarine algae, terrestrial higher plants, heterotrophic bacteria and bacterivorous ciliates.
    Good correlations exist among organic carbon content, oil yield, bitumen content and n-heptadecane anomaly {2×n-C17/(n-C16+n-C18)n-alkane ratio}. The samples with high n-heptadecane anomaly are rich in β-carotane, which suggests that the degree of bottom water anoxia controlled organic carbon content and oil yield, and was related to the contribution of an autotrophic prokaryote which sourced dominant n-heptadecane.
    High C/S ratio and little sulfur compound in the Dsunbayan oil shales indicate that they were deposited in a freshwater environment. The tropical-subtropical climate promoted thermal stratification and bottom water anoxia in the freshwater lakes. The degree of development of bottom-water anoxia was likely controlled by nutrient supply from the surrounding area.
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  • 洪 承燮, 木下 睦, 渡部 孝行, 榎本 兵治
    63 巻 (1998) 3 号 p. 251-257
    公開日: 2008/03/27
    ジャーナル フリー
    Our combustion tube experiments for in-situ combustion with many crude oils of various densities showed that oil produced was emulsified in many cases, but not in some cases. In field operations, emulsification may cause serious problems. Then, at the present study, it was aimed to clarify the mechanism of emulsification and to construct a new physical model for in-situ combustion. Combustion tube experiments were carried out with Yabase crude oil which was easily emulsified. Results may be summarized as follows.
    1) In cases that oil produced was emulsified, w/o emulsion was formed and loose oil was not produced, but a little loose water was produced.
    2) Emulsification is independent of kinds of rock of oil bed, but strongly dependent on the nature of oil.
    3) The water content of emulsion has the upper limit and 75% was the maximum for Yabase crude oil.
    4) In case of Yabase crude oil, emulsion was so strong that it was still stable after several months. The diameter of suspended water was 3-5μm.
    5) Some components in asphaltene of Yabase crude oil may work as emulsifier. It was still effective even when the asphaltene content was reduced from 6.44% as original to 0.5%.
    6) Emulsion in the in-situ combustion may be formed by the condensation of water in the codensation zone. Water condensed is caught in the oil phase as emulsion until the water content reaches the maximum, so that the water in emulsion flows as the oil phase though the loose water flows as the water phase.
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  • 平松 力
    63 巻 (1998) 3 号 p. 258-265
    公開日: 2008/03/27
    ジャーナル フリー
    Calcareous nannofossil as a powerful tool for petroleum exploration was discussed from the aspects of biostratigraphy, sequence stratigraphy and paleoceanography.
    This minute fossil is a biostratigraphically useful indicator, especially for the Plio-Pleistocene and the lower to middle Miocene marine sediments distributed along the coast of the Sea of Japan in the northeast of Japan. It is utilized for the recognition and distinction of the three foraminiferal markers, Globorotalia inflata beds, otherwise frequently confused each other.
    Calcareous nannofossil is used for sequence stratigraphic analysis as well, in petroleum exploration. The peaks of calcareous nannofossil abundance are assigned to the condensed sections in the Gulf of Mexico. They are widely traceable in the region, and they are also useful for the identification of sequences and systems tracts. The change of calcareous nannofossil assemblages caused by sea level changes was apparently recognized in the Quaternary section of boreholes drilled on the edge of the shelf.
    Finally, calcareous nannofossil is applied to the reconstruction of paleoceanographic changes in the pelagic environment. The TN value based on the composition of the Recent calcareous nannoplankton shows a good correspondence with the δ18O curve in three cores collected from the Tasman Sea. The TN curves are obviously related to glacial/interglacial cycles. Therefore, it indicates that the change of sea surface temperature was recorded as the change of nannofloral assemblage.
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