In 1988 we carried out a case study survey at Minamikayabe in the southern part of Hokkaido, Japan. This area is particularly interesting because of its geothermal potential. Seven control wells had been drilled prior to our operation, and also some other information has been available from other survey methods such as gravity, geology, geochemistry, DC resistivity and heat flow. Hence the area is an ideal site for a study of effectiveness of the MT method.The study area is close to the sea and a special care for the coast effect was necessary in our interpretation. The resistivity structure which we derived was found to agree with the well logging data. In this area, the geothermal reservoir is related to a series of fracture existing in an intrusive rock body in the southeast flank of Mt. Nakitsura. The relatively conducting area in our model can be interpreted as corresponding to a fractured zone in the intrusive rock body.Analyses of the data derived from network MT measurements, which we undertook in the present case study, clearly show that dense network measurements could resolve a spatially fine resistivity structure. In order to attain a high spatial resolution of subsurface resistivity structure in a geothermal or a volcanic area, where the subsurface structure is extremely complicated, we show that a dense network MT measurement is indispensable.
A new two-dimensional (2D) magnetotelluric (MT) inversion scheme is proposed in this paper. This scheme is based on a locally two-dimensional analysis in order to minimize computational time and computer memory. The MT governing equation is linearized in terms of the magnetic field and electrical conductivity for the perturbation analysis. The perturbed equation is then multiplied by a test function and integrated over the cross section. Integrating by parts and then substituting this test function with local magnetic fields, a new equation is obtained that is a 2-D variational integral for the electrical conductivity. The new equation is general in the sense that it can explicitly include the horizontal derivative of the magnetic field. If the horizontal derivative term is eliminated, the new equation becomes identical to the Rapid Relaxation Inversion (RRI) scheme proposed by Smith and Booker (1991).
As a part of the "Technology for Increasing Geothermal Energy Recovery" project being undertaken by the New Energy and Industrial Technology Development, Organization. (NEDO), a hydraulic fracturing test was carried out at the TG-2 well in Yunomori area, Iwate prefecture, in November 1992.
Journal Article Assessment of Biological Age by Multiple Regression Analysis Get access Toshiyuki Furukawa, MD, PhD, Toshiyuki Furukawa, MD, PhD Search for other works by this author on: Oxford Academic PubMed Google Scholar Michitoshi Inoue, MD, PhD, Michitoshi Inoue, MD, PhD Search for other works by this author on: Oxford Academic PubMed Google Scholar Fumihiko Kajiya, MD, Fumihiko Kajiya, MD Search for other works by this author on: Oxford Academic PubMed Google Scholar Hiroshi Inada, MD, PhD, Hiroshi Inada, MD, PhD Search for other works by this author on: Oxford Academic PubMed Google Scholar Seiichi Takasugi, MD, Seiichi Takasugi, MD Search for other works by this author on: Oxford Academic PubMed Google Scholar Sugao Fukui, MD, Sugao Fukui, MD Search for other works by this author on: Oxford Academic PubMed Google Scholar Hiroshi Takeda, MD, Hiroshi Takeda, MD Search for other works by this author on: Oxford Academic PubMed Google Scholar Hiroshi Abe, MD, PhD Hiroshi Abe, MD, PhD 1First Dept. of Medicine, Osaka Univ. Medical SchoolOsaka, Japan. Search for other works by this author on: Oxford Academic PubMed Google Scholar Journal of Gerontology, Volume 30, Issue 4, July 1975, Pages 422–434, https://doi.org/10.1093/geronj/30.4.422 Published: 01 July 1975
To handle the real geological environment, 3-D MT inversion studies has been developed by many researchers (Madden et al, 1989; Mackie et al, 1993). The method to calculate 3-D Frechte derivative takes enormous computational time and computer memory, while the RRI method (Smith and Booker, 1991), the approximate one, provides reasonable solution with less computing resource. But it may be liable to the static shift. The method discussed here is expanding the RRI method into the local 3-D area. We have developed a generalized method based on a locally three dimensional analysis to improve the computational efficiency and stability of inversion. The developed algorithm has been realized in the GRRI3D code, which has been tested on synthetic 3-D MT data. The case study includes interpretation of 3-D MT su1'vey conducted in the Minami-kayabe area located in the southern part of Hokkaido, Japan.
MWD (Measurement while drilling) system for geothermal wells has been developed by NEDO (the New Energy and Industrial Technology Development Organization) since 1991. As a part of this system, the drilling support system has been also developed. The well trajectory prediction system is one of this drilling support system including the well trajectory planning system, the well trajectory visualization system, the temperature analysis system and so on, and this system will be used for prediction of well trajectory while drilling and for design of BHA (bottom hole assembly) before drilling. We discussed about the theory of the well trajectory prediction system and its case studies in this paper.
Determination of true formation temperature from measured bottom hole temperature is important for geothermal reservoir evaluation after completion of well drilling. For estimation of equilibrium formation temperature, we studied non-linear least squares fitting method adapting the Middleton Model (Chiba et al., 1988). It was pointed out that this method was applicable as simple and relatively reliable method for estimation of the equilibrium formation temperature after drilling. As a next step, we are studying the estimation of equilibrium formation temperature from bottom hole temperature data measured by MWD (measurement while drilling system). In this study, we have evaluated availability of nonlinear least squares fitting method adapting curve fitting method and the numerical simulator (GEOTEMP2) for estimation of the equilibrium formation temperature while drilling.
