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Suzuki, Masami (Department of Mechanical Engineering, Graduate School of Engineering, The University of Tokyo) | Arakawa, Chuichi (Interfaculty Initiative in Information Studies Graduate School of The University of Tokyo) | Takahashi, Shigeo (Port and Airport Research Institute)
ABSTRACT The wave power generating system using the Wells turbine is installed in the breakwater in Sakata port, Japan, and consists of the air chamber, turbine, generator and safety devices. The purposes of this paper are to reveal the characteristics of each component in this system with the experimental data in the real sea, and to evaluate the accuracy of numerical models used in the simulation. The performance of Wells turbine is examined in detail for the unsteady and full-scale condition, comparing the data of the 1/4 scale model with the steady full-scale one. As for the motion of water in the air chamber, the eigenfunction expansion method is introduced, and the wave height measured 275m away from the chamber is employed for the input of the simulation. It is found that the performance of the system for the wave can be evaluated accurately with the steady-characteristics of the turbine, in the condition that the stall does not happen on the rotor. The angle of attack for the stall depends on the wave characteristics such as the magnitude of unsteadiness, requiring many trials to get the stall angle used by the calculations. The error of the simulation for the total system is finally predicted to be less than 20% when the wave comes within the region of about 20 degree deviation angle. INTRODUCTION A wave power generating system was installed by the First District Port Construction Bureau and Costal Development Institute of Technology in Japan, in a breakwater at Sakata port in front of the Sea of Japan, Yamagata prefecture in Japan from 1989 to 1995 (Goda et al., 1990; Nakada et al., 1992; Oikawa et al., 1994). The system is composed into an air-chamber, a turbine-generator, and a safety system.
Matsunaga, I. (National Institute for Resources and Environment, Tsukuba) | Tenma, N. (National Institute for Resources and Environment, Tsukuba) | Miyazaki, A. (National Institute for Resources and Environment, Tsukuba) | Kuriyagawa, M. (National Institute for Resources and Environment, Tsukuba)
Abstract: The forced flow regime of a hot dry rock geothermal reservoir is characterized using the results of a circulation test of three months duration. During the test, water was injected into granitic basement rock at a depth of 1800 m that had an undisturbed formation temperature of 250°C. Hot water, heated in the reservoir, was recovered from three production wells. Pressure, Temperature, and Spinner (PTS) logging was periodically carried out in the production wells to characterize the fluid flow in the fractured rock. Six tracer experiments were performed during the course of the test. Fluid geochemistry was also monitored to evaluate the mixing process of the injected water with the reservoir fluid, as well as fluid-rock interaction within the fractured reservoir. Several connections between the boreholes were identified, and temperature and flow rate changes at each outlet were measured by PTS logging. A finite element model was used to determine the heat exchange area and the aperture of producing fractures. RESUME: Les circulations artificielles dans un resevoir geothemique Hot Dry Rock ont ete caracterisees durant un test de circulation de 3 mois. L'injection d'eau a ete faite au sein dun massif granitique à une profondeur de 1800 m et à une temperature de 250°C. Les fluides rechauffes durant leur transfert au sein du reservoir artificiel ont ete recuperes dans trois puits de production. Des diagraphies pressiontemperature- debit (PTS) y ont ete realises periodiquement pour mettre en evidence les zones fracturees productrices. Six tests de traçage et un suivi de la composition geochimique des fluides produits ont egalement ete realises pour caracteriser les processus de melange entre I cau injectee et les fluides de formation ainsi que les interactions fluide/roche dans le reservoir fracture artificiel. Plusieurs connections entre le puits injecteur et les trois puits producteurs ont ete reconnues, et variations de temperature et de debit dans chaque zone productrice ont ete mesurees grace aux diagraphies PTS. ZUSAMMENFASSUNG: Das Verhalten eines Hot Dry Rock geothermischen Reservoirs bei erzwungener Durchströmung in einem drei Monate andauernden Zirkulationstest wird dargestellt. Bei diesem Versuch wurde in 1800 m Teufe bei einer ungestörten Gebirgstemperatur von 250°C Wasser in granitisches Grundgebirge injiziert. Das im Reservoir erhitzte Wasser wurde in drei Extraktionsbohrlöchern gefördert- In diesen wurden in regelmaβigen Abstanden Temperatur, Druck und Flieβgeschwindigkeit (PTS - Logging) gemessen, um die Flieβwege im gekluefteten Gebirge zu charakterisieren. Sechs Tracerversuche wurden im Verlauf des Tests durchgefuehrt. Die chemische Zusammensetzung der geförderten Wasser wurde ueberwacht, um den Mischungsprozess des injizierten Wassers mit den Lagerstattenfluiden sowie die gegenseitige Beeinflussung Gebirge/Fluid zu untersuchen. Mehrere Verbindungen zwischen den Bohrlöchern wurden festgestellt, und an den Austrittsstellen wurden Temperatur- und Flieβratenanderungen mit PTS - Logging gemessen. 1 INTRODUCTION In a hot dry rock geothermal energy system, fluid injected from the surface flows through fractures and extracts heat from high temperature rock mass. Hence, the characterization of fluid flow in the fractured reservoir is of significant importance to manage the system. Although the HDR reservoir is located at great depth and has a high temperature, several methods have been applied to characterize fracture system and also the fluid flow regime of artificially created reservoirs. For example, oriented coring, high temperature borehole televiewer (BHTV) logging and formation microscanner have been applied to obtain fracture orientation (Tenzer et al., 1991). Alteration zones and major fractures have also been detected by sonic, electric, and -ray logging in openhole sections (Genter & Traineau, 1992). Injection and interference tests have been conducted to obtain hydraulic parameters of the reservoir rock mass. Microseismicity has also been monitored in boreholes and on the surface to detect fracture extension and changes of reservoir conditions (House et al., 1985; Fehler, 1989).
Abstract Various uses including energy transportation can be considered for the flexible marine riser system. We had an opportunity of studying on a new marine riser system for electric power transmission cable, participating in the power generating system experiment program of Japan Marine Science & Technology Center. The experiment was conducted on a double-catenary riser system which was provided with substand-buoys to cope with the movement of the floating power generating system. This paper discusses the results of system behavior analysis and model experiment and the in service performance of the full-size system. Introduction Japan which is surrounded by the sea on all four sides is in an advantageous position to utilize ocean energy, and as a matter of fact its utilization is one of the important current subjects of inquiry. Wave force which has higher energy density than other forms of natural energy such as wind andsunlight is considered a very promising energy source to be tapped. Japan Marine Science & Technology Center has been working on the floating wave power generating system since 1977, carrying out sea trial of power generation and transmission. To obtain the highest efficiency possible of power generation the power generating system, which will subsequently be also referred to as a wave-power plant, is moored in an area of violent wave motion so that the ocean power transmission cables, especially the riser cable hung under water, are susceptible of deformation under the stress of repeated wave motion. Further, the wave-power plant is moored by slack chains to allow it make wild movements at the mercy of rough waves, storms, currents and other elements. It is therefore necessary to adopt a suitable method of cable installation that will enable the cable to withstand such severe environmental conditions. We developed a riser cable system that meets those conditions and assessed its in-service performance. Mooring System for the Wave-power Plant The wave-power plant "Kaimei" is a ship-shaped buoy which is 80 m in length and 12 m in breadth and has.a total weight of about 800 tons. This system is deslgned to carryon board 13 air-turbine generating units. The current prototype is equipped with 5 power generating units whose combined output is 560 kW. The power generating system is moored about 3.5 km off Yura, Yamagata Prefecture, and the power generated is transmitted to land via a submarine cable system consisting of a marine riser cable and a field splice as shown in Fig. 1 and Fig. 2. The configuration of the wave-power plant is indicated in Fig. 3. This wave-power plant is tethered fore with four chains hung in different directions. This mooring system is designed so that the floating plant can freely move in all directions in a relatively wide area, but the turning of the floating plant is restricted within limits of ±50 degrees by auxiliary chains at the stern. The mooring site is located in one of limited sea areas of Japan where billows reach a wave height of 6 to 10 min the winter season.
GEO CHEMICAL RELATIONSHIPS BETWEEN JAPANESE TERT JARY OILS AND THEIR SOURCE ROCKS AGE In order to identify the source rocks for the Japanese Tertiary oils, about 250 shale and mudstone samples were selected from oil fields in the Akita and Yamagata Prefectures, in which the eight Miocene and Pliocene stratigraphic units, shown in Fig. 1, have been established. In addition, 19 crude oil samples were collected from a number of different fields and producing horizons for oil to rock correlation studies. Scope of the study for the source rock identification has covered essentially the examinations from the following points :comparison of the analytical results with accepted "source rock criteria" suggested AKITA TERRACE OEPOSITS jg KATANISHI F. WAKIMOTO F. 0 KITAURA F. FUNAKAWA F u O NISHIOGA G. LITHOLOGY SAND SILTSTONE SILTSTONE SANDSTONE GRAV MUDSTONE BLACK MUDSTONE HARD BANDED SHALE SANDSTONE SILTSTONE I d CONGLOMERATE 8 F> WODUCI NG ZONES t i Fig. 1-Tertiary stratigraphic units and oil-producing horizons in Akita Basin, Japan.CARBON PREFERENCE INDEX (CPI) The mature n-alkanes extracted from shales of the Onnagawa formation are characterised by petroleumlike CPI values which range from 0.9 to 1.5. By contrast, the CPI values of extracts from formations younger than the Onnagawa formation are almost all greater than 1.5, indicating that their contained hydrocarbons are less mature than crude oils. POLYCYCLIC AROMATICS WITH FIVE-RING PERYLENE STRUCTURE Six types of polycyclic aromatics among those from the samples studied have been distinguished, based on their spectral characteristics. The samples from the Onnagawa formation showed markedly fewer positive indications and significantly lower concentrations of those polycyclic aromatics (except the samples from the marginal parts of the sedimentary basin), than the samples from formations younger than the Onnagawa. Samples from the younger formations showed positive indications of polycyclic aromatics ranging from 0.001 to 13-218 ppm. On the contrary, no polycyclic aromatics have been detected in 19 crude oils collected from different oil fields and producing horizons. Ni/V PORPHYRIN RATIO by prior studies, (2) consideration of the influence of The ratio of nickel to vanadyl porphyrins in 19 postdepositional history on source bed development samples of Japanese crude oil ranges from 0.21 to 6.85. and (3) organic geochemical correlations between the About 60 % of the 250 rock samples studied had Ni/V produced crude oils and their presumed source rocks. porphyrin ratios within this range and all those came Here, however, only some properties found to link the from Miocene formations. All porphyrin ratios from crude oils and their presumed source rocks are samples in the Wakimoto formation and younger presented, as shown in Fig. 2. Pliocene formations fell outside the crude oil range. The percentages of rock sample