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Volume 53 (1988)
- Issue 6 Pages 463-
- Issue 5 Pages 337-
- Issue 4 Pages 251-
- Issue 3 Pages 199-
- Issue 2 Pages 119-
- Issue 1 Pages 1-
Volume 53, Issue 3
Displaying 1-5 of 5 articles from this issue
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Part 3: Akita Area and Oga PeninsulaTokiyuki SATO, Toshiaki TAKAYAMA, Michio KATO, Tetsuro KUDO1988 Volume 53 Issue 3 Pages 199-212
Published: 1988
Released on J-STAGE: March 27, 2008
JOURNAL FREE ACCESSThe calcareous nannofossil and the foraminiferal assemblages of the uppermost Cenozoic formations distributed in the Oga Peninsula and the Akita area are described. Among twelve calcareous nannofossil biohorizons recognized in the Quarternary sequences in the North Atlantic Ocean during DSDP-IPOD Leg 94 (TAKAYAMA and SATO, 1987), seven calcareous nannofossil biohorizons are detected in this area. In the Oga Peninsula, the upper Funakawa and the lowest Kitaura formations are late Pliocene, and the middle to upper Kitaura and the Wakimoto formations are Pleistocene in age based on the results of DSDP-IPOD Leg 94. The Tentokuji and the Sasaoka formations, the uppermost marine sediments in the Akita area are late Pliocene in age. Consequently, the Tentokuji and the Sasaoka formations in the Akita area are correlative with the upper Funakawa to the lowest Kitaura formations in the Oga Peninsula.View full abstractDownload PDF (822K) -
Amane WASEDA, Mamoru OMOKAWA1988 Volume 53 Issue 3 Pages 213-222
Published: 1988
Released on J-STAGE: March 27, 2008
JOURNAL FREE ACCESSChemical and isotopic compositions were analyzed to characterize the genetic origin of natural gases from various occurrences (production gases, water-dissolved gases, coal gases, surface gas seeps) in Japanese oil and gas fields.
Bacterial gases and thermogenic gases are characterized in two diagrams using the relationships of hydrocarbon compositions and methane 13C, and of methane 13C and ethane 13C, respectively. A significant proportion of production gases assosiated with oils is mixtures of bacterial gases and thermogenic gases. These diagrams can also reveal the influence of secondary processes such as migration and oxidation of hydrocarbons. Surface gas seeps are usually affected by such secondary processes.
Origin and migration of gases in the northern part of Niigata oil and gas fields might be different from those in the southern part of the area. Production gases in the south (Nagaoka-Kasiwazaki area) consist of only thermogenic gases and have no relation to their reservoir depth or age. On the other hand, gases in the north (Niigata-Kitakanbara area) mainly consist of mixed gases; the younger reservoirs contain a large quantity of bacterial gases, while the older reservoirs mainly consist of thermogenic gases. This areal distribution might be controlled by the geological factors which are discussed in this paper.View full abstractDownload PDF (627K) -
Part 2: Maturity Indicator of KerogenTsutomu MACHIHARA1988 Volume 53 Issue 3 Pages 223-229
Published: 1988
Released on J-STAGE: March 27, 2008
JOURNAL FREE ACCESSEighteen kerogen samples isolated from the Noshiro GS-1 cores (589-3, 510m) were examined by pyrolysis gas chromatography. Pristene (prist-1-ene) compound was detected in the pyrolyzates of all the kerogens, and the ratio of the pristene to C17 alkane (Pr=/C17) in the pyrogram decreased with increasing burial depth of the samples. The ratio correlated well with vitrinite reflectance (Ro) data. A difference of the particle size of kerogen (>25μm and <25μm) did not affect the Pr=/C17 ratio. Although the number of the samples in this experiment was small and only one well was investigated, it has been suggested that the Pr=/C17 ratio can be used as a useful maturity indicator of kerogen (Ro<0.6%). It would be especially usefull to estimate the maturation level of kerogens containing no vitrinite maceral.View full abstractDownload PDF (422K) -
On the Behavior of Displacement and Flow of OilHeiji ENOMOTO, Cheng-Xie HONG, Shozo TANAKA, Tadashi CHIDA1988 Volume 53 Issue 3 Pages 230-235
Published: 1988
Released on J-STAGE: March 27, 2008
JOURNAL FREE ACCESSSimulation study was carried out to investigate the behavior of fireflooding in reservoirs and to obtain basic informations for designing and/or screening fireflood projects, through a sensitivity study. The simulator used has been reported elsewhere (JJAPT 52, 5, 1987). Parameters selected were (1) initial water saturation (or initial oil saturation), (2) absolute permeability, (3) porosity, (4) thickness of reservoir (as a parameter representing heat loss to the upper and lower strata), (5) residual oil saturation, (6) density of oil, and (7) air injection rate. As a part of the study, general phenomena of fireflooding is described in the present report.
It should be noted that the whole process of fireflooding can be understood to consist of four processes; that is (1) the initial air injection process, where the air injection rate required is achieved, (2) the initiation of in-situ combustion and subsequent oil accumulation to form oil bank, (3) main production process following the oil bank formation process, and (4) process of little oil production after the production of oil in oil bank. It was also shown that the duration of the production period as the third process described above depended on the initial oil saturation, but the production rate was independent of the initial oil saturation.View full abstractDownload PDF (362K) -
Satoshi AKIBAYASHI, Ping ZHOU, Kozo YUHARA1988 Volume 53 Issue 3 Pages 236-242
Published: 1988
Released on J-STAGE: March 27, 2008
JOURNAL FREE ACCESSThis paper describes a simplified three-dimensional numerical model for production behavior of the Mobara-type water-dissolved natural gas reservoir composed of alternating beds of sandstones and mudstones. It is assumed that water and gas flow horizontally through the sand-stones and vertically (in one dimension only) through the mudstones. Finite difference approximation method is used to solve the differential flow equations.
Application of the model to a practical Mobara-type field in Chiba Prefecture shows very good coincidence between the calculated and the measured values for the average gas-water-ratio of all the production wells.
Calculation results show that the production behavior remains ordinary-type if gas does not migrate from the mudstones to the sandtones even though pressure is maintained at a constant and a large amount of free gas is supplied at the boundaries, provided that the reservoir be isotropic and homogeneous.View full abstractDownload PDF (399K)
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