The middle to upper Eocene Poronai and overlying Oligocene Momijiyama formations in Hokkaido are the major Paleogene strata studied by many workers in Japan. Recent progress in biostratigraphy and foraminiferal paleoecology requires a thorough revision of the regional geohistory interpretations.
Depositional environments of the Poronai and Momijiyama formations are discussed based of the re-interpretation of the published foraminiferal data sets. Transgression, which is recognized in the lower sequences of the Poronai Formation in the Yubari, Ashibetsu and Ikushunbetsu areas, reached a maximum water depth in the upper bathyal facies. In addition, a temporal regression, which occurs in the middle part of the Poronai Formation in the Yubari area, is related to the eustatic sea level drop in the beginning of Late Eocene. Conversely, shallower water depths are inferred in the Yufutsu-Umaoi and Hobetsu districts. Based on these paleobathymetric interpretations and the distributions of the mega-fossil zones, the marine transgression during the deposition of the Poronai Formation was from northeast to southwest.
Stratigraphic relationship between the Poronai Formation and the underlying Ishikari Group, which has been controversial, is demonstrated to be unconformable mainly due to the existence of transgressive phase at the basal part of the Poronai Formation.

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Microbial EQR (MEOR) field test was carried out in Fuyu oilfield, China during 1996-2001. In Fuyu oilfield, patterned waterflooding has been applied for over 20 years and the current averaged water cut in test area has reached at approximately 90% due to the existence of high permeable layer.
In this field test, a microbe named CJF-002 was applied. CJF-002 has a feature of producing insoluble polymer by feeding molasses as a nutrient. This MEOR test has focused on profile modification process by produced insoluble polymer in the reservoir to reduce water channeling. Prior to the field test, a tracer test was carried out to measure the baseline of reservoir characteristics. CJF-002 and molasses were injected from two water injectors. Increases of oil production and reduction of water cut were observed soon after CJF-002 and molasses injection started. After two-month microbial treatment, total oil rate in the test area increased approximately three times larger than before. The chemical and biological monitoring during the field test proved that CJF-002 survived and produced some amount of insoluble polymer in the reservoir. Result of tracer tests also indicated that microbial injection could improve the sweep pattern of injection water.
Moreover, according to the simulation study of MEOR field test, the production performance of MEOR field test has successfully simulated by assuming the insoluble polymer had reduced the permeability of high permeable zone to 1/10 of its original value.
This paper presents the successful results of MEOR field test and discussion on the effects of microbial profile modification process.

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In order to model the in-situ superwet combustion method for enhanced oil recovery, key phenomena of the superwet combustion reaction and the reaction rate were investigated. Firstly, a batch type reactor was used to investigate phenomena related to the wet oxidation reaction in case of a limited oxygen supply. It was found that (1) a notable change of oil in quality did not occur, (2) acetic acid was the major intermediate product with minor products of acetones and ketones as well as other carboxylic acids, (3) water-soluble intermediate products did not significantly lower the interfacial tension with oil, and (4) 40 percent of oxygen supply was consumed to produce carbon oxides.
Secondly, a continuous flow reactor was used to obtain reaction rate equations for wet oxidation. Experiments were carried out with a sand pack as a reactor, using injection gases of different oxygen concentrations, at temperatures ranging from 200 to 275°C. It was found that the reaction order for oxygen concentration was unity, and the activation energy was 85.6 kJ/mol. Furthermore, the rate equations for the oil consumption and the heat of combustion were derived on the basis of the rate equation for oxygen consumption.

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We describe procedures for estimation of the petrophysical properties of fault rocks and the stress regime in normal faults as incorporated in the PC software (FAULTAP) developed at the Technology Research Center of Japan National Oil Corporation (JNOC/TRC). A quantitative appraisal of the petrophysical properties of fault rocks provides key information for fault sealing assessment and reservoir management. Empirical evidence shows that the permeability of fault rocks appears to be approximately two orders of magnitude lower than that of the host reservoir rocks. Among the deformation processes in clastic rocks, shale smear by faulting seems to be a most efficient mechanism of permeability reduction in fault rocks. The permeability of fault rocks has an inverse relationship with the clay content incorporated from the host rock as well as with the depth of fault rock and fault displacement. The relationship between clay content and pore throat radius in fault rock forms a basis for calculation of the capillary pressure of fault rock and the hydrocarbon column height that a fault can laterally support. The integrity or the failure of fault seals is crucially dependent upon how various portions of the fault surface are subjected to stress accumulation in the recent geological time. Simple methods for calculation of in-situ stresses on normal faults are presented for evaluation of fault failure by slip tendency or dilation tendency. An integration of fault failure and shale smear parameters provides a better assessment of fault sealing or potential leakage in response to the recent stress regime or changes in the pressure regime during field production.

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