Journal of the Geothermal Research Society of Japan
Online ISSN : 1883-5775
Print ISSN : 0388-6735
ISSN-L : 0388-6735
Volume 20, Issue 4
Displaying 1-4 of 4 articles from this issue
  • Investigation about Friction Factor
    Masahiro TAKAHASHI, Ken-ichi KIKUCHI, Satoshi AKIBAYASHI
    1998 Volume 20 Issue 4 Pages 243-261
    Published: October 25, 1998
    Released on J-STAGE: February 05, 2010
    JOURNAL FREE ACCESS
    A wellbore flow simulator (WELCARD-II) for liquid-single and two-phase flows in geothermal wells has been developed, which is applicable to the flow regimes up to annular-mist flow. The applicability of many constitutive equations for friction factor to actual geothermal wells and the availability of the wellbore simulator have been investigated by the comparison of computational results with measured values of borehole temperature and pressure in the Kakkonda geothermal field in Japan. The results are as follows.
    1) In the domain of liquid-single flow, the calculation by the wellbore simulator with Blasius's equation for friction factor (λ=0.3164 Re-0.25) at Re≤3.0×106 and Weisbach's equation for friction factor (λ=0.0144+0.0095/j1/2) at Re>3.0×106 was very satisfactory.
    2) In the domain of two-phase flow, the calculation by the wellbore simulator with the equation for friction factor (λ=0.032) at Rem≤2.6×107 and the equation for friction factor (λ=0.046Rem-0.2) at Rem>2.6×107 was also very satisfactory.
    3) WELCARD-II is applicable to the two-phase flow in the wellbore up to annular-mist flow regime and has the advantage of overcoming the problems in calculations such as non-continuity of temperature/pressure profiles at flow regime boundaries.
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  • Daisuke HAGA, Yuichi NIIBORI, Tadashi CHIDA
    1998 Volume 20 Issue 4 Pages 263-274
    Published: October 25, 1998
    Released on J-STAGE: February 05, 2010
    JOURNAL FREE ACCESS
    This study focused on the response analysis of liquid tracer in gas-liquid, two-phase steady flow in porous media. The tracer tests were conducted in a column filled with glass beads and uniformly saturated with water and gas. First, it is shown that the conventional advection-dispersion equation (ADE) can not explain the breakthrough curves of tracer tests under two-phase flow conditions. The experimental breakthrough curves have an earlier peak and a longer tailing compared with the breakthrough curves described by ADE. The water saturation is not always uniform in the particle region. The mathematical model consisted of a high water saturation layer and low one, between which mass transfer was assumed. Mass balance equations were derived on these assumptions of the two-phase flow in a porous medium. The model calculations well agreed with the experimental data. When fundamental equations are solved by the finite-difference method, it is well known that the standard numerical techniques lead to numerical oscillation in the advection term in the equations. The third-order upstream method applied in this study could reduce the oscillation. Also, this study examined parameter estimation technique by use of optimization programs. Unknown parameters in this model were successfully estimated by the SIMPLEX method.
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  • Shinji YAMAGUCHI, Satoshi AKIBAYASHI, Yuzuru EGUCHI, Kouichi KITANO
    1998 Volume 20 Issue 4 Pages 275-288
    Published: October 25, 1998
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
    The Ogachi hot dry rock test site in Akita Prefecture is one of three active hot dry rock test sites in the world; the other two sites are the European hot dry rock test site at Soultz in France and the Hijiori hot dry rock test site in Yamagata Prefecture. In 1997, a 48 days circulation test was conducted at the Ogachi hot dry rock test site. In the experiment, 20°C water was injected at the flow rate between 200l/min and 700l/min and 120°C hot water was recovered from a production well. In this paper, this experiment was modeled by TOUGH2 applying a fractured model to an artificially fractured zone and a porous model to a non-fractured zone. The simulation results showed a relatively good match between calculated and measured production flow rates when the skin factor of the production well was -0.5. With this model, some production performances of supposed new production wells were predicted . From the results, it was suggested that a new production well would be better to be drilled apart from the existing injection well to a certain extent and the recovery rate was estimated to be about 20% per new production well.
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  • Shinji OHSAWA, Yuki YUSA, Kazutoshi OUE
    1998 Volume 20 Issue 4 Pages 289-292
    Published: October 25, 1998
    Released on J-STAGE: August 07, 2009
    JOURNAL FREE ACCESS
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