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ABSTRACT No preview is available for this paper.
Measured gravity anomalies typically contain both regional and Figure 2 shows a local negative anomaly in the basin residual components, the separation of which is often the fist superimposed on a broad regional anomaly, both as measured step in interpretation. In most exploration work, the regional is on the topographic surface and as if reduced to the datum.
The P/S separation method is based on the twodimensional convolution filters for separation of P-and S-linear relation between the vertical waves will be presented.
To conclude, apparent slowness and polarization angle. Modelling the limitations of the method and future applications will be dis-the data as the sum of a small number of plane waves, rather cussed.
The location of gravity measurements is one such application. Much has been SATELLITE GEOMETRY written about the centimeter surveying precision of GPS, as well as the meter level accuracies obtainable in the Because the satellite geometry, and the change in the navigation mode. However, little or nothing has been stated geometry, are prime factors in determining the success or about decimeter surveying accuracy. This paper presents failure of an observation, it is very important that we look at results in the investigation of decimeter accuracy surveys.
The concern has obviously been how well the two PHASE ENCODING TECHNIQUES (or potentially more) source signals could For more complete separation of two be separated.
MEASUREMENTS Validation of the stnxmer position as derived from the The technique of multipath acoustic ranging can be used compass data has always proved difficult. Attempts have been whenever two or mote streamers are deployed. The method made to ovetcome some of these difficulties by using other consists of mounting transducers at intervals along each streamer techniques to position the two ends of the streamer.
When both primary P and converted S waves are used, non-uniqueness assoriat,ed with the estimation of the physical properties can be effectively removed. Where differen1 events such as primary P and converted S waves overlap within a short time window, polarization and apparent siowness ran not be determined independentl!.
It is of course effective to While the tube wave is generated even in the open hole, improve the hardware of the system and data processing the velocity of the tube wave in the cased hole tends to be technique for the improvement of the signal to noise ratio. For approximated to the velocity of water as its upper limit, example, the expansion of the intervals between the source and Therefore, different from the open hole in which the separation the geophones with more powerful source is advantageous to of the S wave from the tube wave is rather easy because of detect the low frequency S wave. As for the signal processing the arrival of the former at the geophones being considerably technique, low pass filter, stacking, cross correlation and earlier than the arrival of the latter al the identical points, the statistical analysis for the waveform are probably effective, The cased hole often entails the difficulty with the separation, technique using the fractal-based theory seems to be effective to determine the S wave arrival time The result from the cased 3) Influence on the frequency characteristic of hole coincides with the one from the open hole. This comparison the S wave leads to the conclusion that the possibility to realize the S wave The existence of the casing acts as low pass filter on the log in a cased hole seems high, though the problem is left S wave, in which the lower the S wave velocity is. the lower pending while relying on the future study to attain the the cutoff frequency is (Kitsunezaki, 1981.
Seismic Cross-borehole Imaging of the Near Surface Using Tomography And Prestack Migration In Elastic Physical Models
Balch, A.H. (Colorado School of Mines) | Chang, Hyunsam (Colorado School of Mines) | Hofland, Gregg (Unocal) | Ranzinger, Kurt (Green Mountain Geophysical) | Schneider, W.A. (ExxonProduction Research)
The problem of using seismic cross-borehole measurements to image the subsurface is an important PRESTACK MIGRATION one. There are applications to the analysis of abandoned mine workings, mapping of petroleum reservoirs and The principles of prestack migration apply to crossborehole other valuable mineral deposits, delineation of fracture data as well as they do to VSP's and surface zones relevant to hazardous waste disposal, and military data. These principles have been described by applications related to the detection of hostile tunnels. Claerbout,l971, and Whitmore and Lines, 1986, amongst Raw cross-borehole data are complex.
- Energy > Oil & Gas > Upstream (1.00)
- Government > Regional Government > North America Government > United States Government (0.48)