[in Japanese]

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Elemental analysis, X-ray diffraction, infrared absorption and electron spin resonance have been used to characterize the kerogens from the Miocene muddy rocks between 500 and 4500m in depth obtained from the MITI Hamayuchi Borehole in the northern part of Hokkaido. The progressive maturation of the kerogen properties observed were discussed, compared with the data of the extractable organic matter in the same samples which had been already reported by ATAKE (1973) and ASAKAWA (1975).
The results are as follows:
1) The kerogens are clearly classified into two definite groups in C-H-O composition, one being more than 79% in carbon content from the samples deeper than 3200m in depth and the other less than 75% from those shallower than 2100m.
2) X-ray diffraction spectra of all of these kerogens correspond to "graphite-d₃" of LANDIS' classification (1971).
3) Infrared absorption analyses suggest that the ratios of absorption intensity of C=O at 1700cm^-1 to aromatic C=C at 1600cm^-1 could be a useful parameter to identify the kerogen maturation.
4) ESR measurements could be also a useful tool for estimating kerogen maturity only for the deeply buried kerogens.
5) Maturity of kerogens increases progressively with an increase of the concentration and maturity of the extractable organic matter included at the depth of 2000-3400m from the surface. This evidence suggests the extractable organic matter in the muddy rocks originates from the breakdown of hydrocarbon side chains of kerogens by natural pyrolysis during diagenesis.

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It has been studied to develop a apparatus for analysis of core, in which permeability, porosity, and other physical properties could be measured under high confining pressure simulated deep reservoir condition.
In this apparatus, the confining pressure was applied to a maximum value of 500kg/cm² and internal fluid pressure could be kept in constant to common used value of 350kg/cm² by two pressure regulators. The pressure difference of both sides of core was measured by electrical transmitters of Rosemount Eng. Co. The flow rates of gas were measured by soap film meter.
In the results of these experiments the following relation was observed between permeability and effective stress of each core. When confining pressure was much higher than fluid pressure, the permeability reductions were propotional to the confining pressure. On the other hand, after the fluid pressures reached to a value of about 200kg/cm² in effective stress, the permeability increased and its value might be twice compared with original one.
These results have implied that permeability was not only a function of effective strese but also depended on fluid pressure in core.

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Vapor pressure of condensate is very high, so that a large amount of vapor loss occurrs when pumping operation is taking place and when temperature change in vapor space is occurring. This vapor loss was classified into ten factors, and these factors were calculated individually and were analized quantitatively. Since the data were collected during severe wintertime, breathing loss was very little. Filling loss took the main and indicated 0.28% of total quantity of operating oil. The dispersion of data showed error in reading the liquid level meter of tank. Since the total quantity of operating oil is a little, vapor recovery system is not suitable. Breathing loss during summertime must be studied as the following theme.

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