Development of a downhole seismic source with controlled waveform; Hakei seigyogata kochu shingen no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Kuroda, T; Ikawa, T [Japex Jeoscience Institute, Tokyo (Japan); Sato, T [Meiho Engineering Co. Ltd., Tokyo (Japan); Kakuma, H [Akashi Corp., Tokyo (Japan); Onuma, H [Engineering Advancement Association of Japan, Tokyo (Japan)

1997-05-27

A downhole seismic source which can output continuous waves having arbitrary waveforms was developed. The development was targeted to make tomographic exploration purposed to evaluate geological properties of a ground bed before and after constructing a building in a ground several hundred meters deep from the ground surface. The source is considered to be used in an environment consisting of soft rocks or more robust rocks and having no casing. It can be used in a well hole having a diameter of 100 mm, is capable of measuring P and S waves in a distance between well holes of up to 100 m, can be used at a depth of up to 500 m, and can output waveforms having seismic source spectra of up to 1000 Hz. An oscillation actuator using laminated piezo-electric elements was used for the oscillation element. The seismic source consists of a hydraulic device to clamp the equipment onto hole walls, piezo-electric elements as the oscillation element, and an inertia weight for applying vibration from above and below. To make an oscillation, the main body is first clamped on the hole wall. For horizontal oscillation, the piezo-electric elements contained in a clamping device provide the horizontal oscillation. For vertical oscillation, the piezo-electric elements placed below the main body oscillates the inertia weight. The initially targeted specifications have been achieved. 3 refs., 4 figs., 1 tab.

Active SWD using monochromatic source wavelet; Tan`itsu shuhasu no shingen hakei wo mochiita active SWD

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Tsuru, T; Kozawa, T [Japan National Oil Corp., Tokyo (Japan); Taniguchi, R [Mitsubishi Electric Corp., Tokyo (Japan); Nishikawa, N [Fuji Research Institute Corp., Tokyo (Japan); Matsuhashi, K

1997-05-27

As part of developing efforts for physical exploration technologies for oil reservoirs, this paper describes development of an active seismic while drilling (SWD). The SWD is a seismic exploration method to acquire records equivalent to VSP using seismic waves generated from a bit executing excavation, and is capable of detection and control on a real time basis during the excavation. However, the drawback is that it is subjected to a limitation in the bit. To eliminate this limitation, an artificial seismic source method was devised. In other words, this is an SWD utilizing an artificial seismic source. The contrivance is such that a shot sub containing a magnetic distortion oscillator is attached directly above a bit to generate vibration artificially, and try to utilize larger seismic energy by combining this vibration with that generated from the excavating bit. Frequency band in the seismic source is as narrow as nearly a single frequency waveform. Preparing a time-depth curve from the data and identifying position of a bit making excavation requires reading the initial travel time. A waveform recognition technology was applied, which utilizes a matching evaluation function used in pattern recognition. This made waveform recognition possible at high accuracy. 2 figs., 1 tab.

Sensing of subsurface faults based on an imaging technique for teleseismic waveform data. 2. Feasibility study for application to oblique incidence, multi-event and noise data; Enchi jishin hakei data wo mochiita chika kozo imaging ni yoru chichu danso kenshutsu no kokoromi. 2. Naname nyusha, multi event, noise wo fukumu hakei eno tekiyo

Energy Technology Data Exchange (ETDEWEB)

Murakoshi, T; Takenaka, H; Saita, T [Kyushu University, Fukuoka (Japan). Faculty of Science; Suetsugu, D [Building Research Institute, Tokyo (Japan); Furumura, T [Hokkaido University of Education, Sapporo (Japan)

1996-05-01

An examination was made on the method in which imaging of subsurface was carried out with teleseismic waveform data for sensing of faults. In the examination, an experiment was done on the sensing of faults with higher precision, by applying oblique incidence as well as perpendicular upward incidence of SH plane waves, and thereby stacking the imaging in plural events. In numerical experiments, 28 observation points were arranged at 500m spaces apart on the surface, and the incident waves were made the SH plane waves having a bell-shaped time function, with incidence made at an angle varied as 0{degree}, +15{degree} and -15{degree} from the lowest layer of a model. In the calculation of the wave motion field, a difference calculus with secondary accuracy was used for both time and space. In addition, data was prepared with a random noise added to a synthesized waveform to be used as observation data. The calculated waveform data were likened to the observation waveform, to which the method for imaging faults was applied. Consequently, it was noted that satisfactory results were obtained compared with the case where faults were sensed by one event alone. 5 refs., 4 figs.

Study of complex resistivity measurement using current and potential waveform data; Denryu to den`i hakei data wo riyoshita fukusohi teiko sokutei no kento

Energy Technology Data Exchange (ETDEWEB)

Shima, H; Sakurai, K; Yamashita, Y [OYO Corp., Tokyo (Japan)

1997-10-22

This paper proposes a measurement method for complex resistivity using both current and potential waveforms. This method was applied to actual data. Especially, chargeability was discussed among complex resistivities. A method was proposed for determining the complex resistivity. At first, digital measurements of both current and potential waveforms were conducted. For the potential waveform, zero-order self-potential was canceled. Then, the FFT technique was applied to both current and potential waveforms, to determine both current and potential in the frequency domain. Hereafter, complex resistivity was determined through simple division. Since the inductive coupling was observed at higher frequencies, it was difficult to apply Cole-Cole model, simply. However, the inductive coupling could be removed using proper sampling frequency. Thus, a proper Cole-Cole dispersion curve could be obtained. Using this Cole-Cole dispersion curve, new chargeability could be defined. A linear relation between this chargeability and the ordinary time domain chargeability was made clear. 4 refs., 10 figs.

Optimization of the ship type using waveform by means of Rankine source method; Rankine source ho ni yoru hakei wo mochiita funagata saitekika ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Hirayama, A; Eguchi, T [Mitsui Engineering and Shipbuilding Co. Ltd., Tokyo (Japan)

1996-04-10

Among the numerical calculation methods for steady-state wave-making problems, the panel shift Rankine source (PSRS) method has the advantages of rather precise determination of wave pattern of practical ship types, and short calculation period. The wave pattern around the hull was calculated by means of the PSRS method. The waveform analysis was carried out for the wave, to obtain an amplitude function of the original ship type. Based on the amplitude function, a ship type improvement method aiming at the optimization of ship type was provided using a conditional calculus of variation. A Series 60 (Cb=0.6) ship type was selected for the ship type improvement, to apply this technique. It was suggested that optimum design can be made for reducing the wave making resistance by means of this method. For the improvement of Series 60 ship type using this method, a great degree of reduction in the wave making resistance was recognized from the results of numerical waveform analysis. It was suggested that the ship type improvement aiming at the reduction of wave-making resistance can be made in shorter period and by smaller labor compared with the method using a waveform analysis of cistern tests. 5 refs., 9 figs.

PWM control of current source type six-phase inverter with improved waveforms by coupling reactor; Ketsugo reactor ni yori hakei kaizen sareta denryugata rokuso inverter no PWM seigyo

Energy Technology Data Exchange (ETDEWEB)

Inami, K.; Danjo, M.; Kondo, Y.; Yamada, M. [Niihama Technical College, Ehime (Japan); Toki, K. [Shikoku Electric Power Co., Inc., Kagawa (Japan); Heike, J. [Shikoku Instrumentation Co. Ltd., Kagawa (Japan)

1998-10-01

A PWM method has been applied to a high capacity six phase current source inverter system in order to obtain sinusoidal output voltage and current. In this system, the three-phase coupling reactor is connected between the inverter output and an induction motor used as a load. Then the reactor eliminates harmonic components included in the inverter output current except 12k {+-} 1 (k=1,2,3)th order. As a result, the distortion factor of the inverter output current decreases. But the resonant circuit is composed of the capacitance of filter capacitor and the induction motor leakage inductance. Then the resonance current is superimposed on the induction motor phase currents. To solve this problem, the optimal PWM pattern is derived, so that the resonant current becomes very small. The order of the resonant frequency component of the induction motor phase current depend on the inverter frequency. Then total inverter frequency range is divided into several areas. The optimal PWM pattern is derived in each areas. As a result, the use of each optimal PWM pattern allows us to drive the induction motor, over a wide range of speed, under the condition of small distortion factor of phase currents. 5 refs., 10 figs., 1 tab.

Aliasing characteristics of tau-P transform and is application to signal and noise separation; Tau-P henkan no aliasing tokusei to hakei iji wo koryoshita S/N bunri

Energy Technology Data Exchange (ETDEWEB)

Kawabuchi, H; Rokugawa, S; Matsushima, J; Ichie, Y [The University of Tokyo, Tokyo (Japan); Minegishi, M; Tsuburaya, Y [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

1997-05-27

With respect to the tau-P transform method as a signal and noise (S/N) separation technology used in seismic exploration using the reflection method, a discussion has been given on conditions for the post S/N separation by the tau-P transform to function more effectively. Averaging the energy in performing the tau-P transform makes the wave energy scatter to a certain range. As a result, an aliasing phenomenon appears, in which noise is superimposed on the post-processing record. As a result of the discussion, it was verified that satisfying the two equations of G. Turner is effective in order to reduce the aliasing and maintain the relative amplitude. However, in actual calculation accuracy, waveform change was recognized to some extent, particularly amplification of events in low frequencies, and low restorability in higher frequencies. It was also observed that a method to give the tau-P region a two-dimensional Fourier transform and perform the same processing as an f-k filter can remove aliasing more simply and effectively than the HVF, and improve the S/N ratio maintaining the amplitude at the current level. 5 refs., 13 figs.

Study on the cutting quality by rectangular pulse wave of the CO sub 2 laser. CO sub 2 laser no kukei pulse hakei ni yoru setsudan hinshitsu no kenkyu

Energy Technology Data Exchange (ETDEWEB)

Kanaoka, M. (Mitsubishi Electric Corporation, Tokyo (Japan))

1992-05-20

The paper studies effects of laser power parameters on processing quality in cutting metal by the use of rectangular pulse waveform formed by the triaxial cross flow resonator. As a result, the heat affected zone appearing around the kerf expands from the upper part to the lower part, and by increasing pulse peak power the width of the heat affected zone from the central part of board thickness to the lower part lessens. Further, by lowering pulse frequency, the width of the heat affected zone appearing around the kerf from the central part of board thickness to the lower part lessens. Also, by lowering frequency, an energy absortion rate of the workpiece to be processed decreases. Cutting surface roughness is affected by pulse peak power, and the high the peak value is, the better the surface roughness is improved. In addition, the surface roughmess is affected by pulse frequency, and the higher the frequency is, the better the surface roughness is improved. 6 refs., 15 figs.