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.
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.
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.
本報告でに,砕屑岩の正断層における断層岩の浸透率,シール能力,および断層の応力状態を評価する方法について,石油公団石油開発技術センターが開発した断層シール能力評価ソフトウェアFAULTAPを用いて報告する。Sorkhabi et al (2002)で報告した断層面の幾何学解析,シェールスミア解析の結果を用いて,これら石油のトラップに関連する断層岩物性の評価を行っている。 断層岩の浸透率や毛細管圧力などの物性について定量的に評価することは,断層シール能力評価や隼産層の管理のたあに重要である。経験的に,断層岩の浸透率は貯留岩の浸透率と比べて二桁ほど小さいことが知られている。砕屑岩の変形過程で断層に発達するシェールスミアは,断層岩の浸透率減少の最も効率的なメカニズムであろう。FAULTAPでは,断層岩の浸透率が,泥岩含有量,埋没深度,断層変位などと逆の相関にあること利用して断層岩の浸透率評価を行っている。また泥岩含有量と孔隙径の関係を利用して,断層岩の毛細管圧力や断層が保持できる炭化水素高を計算している。 断層シールの成否は,断層面での応力が大きく影響するため,正断層における最も簡単な原位置応力の推定方法として断層面でのスリップテンデンシーやダイレーションテンデンシーを求め評価している。シェールスミア解析や断層物性評価と統合することによって,断層シール能力や生産段階における断層による圧力バリアーなどの評価をより正確に行うことができる。