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Engineering geomorphology: a UK perspective
360A 916231 Engineering geomorphoiogy: a UK perspective Griffiths, J S, Hearn, G J Int Assoc Engng Geol Bull V42, Oct 1990, P39-44
916235 Measurement of borehole seismic noise with hydrophones Chouzenoux, C Geophysics V56. N3, March 1991, P397-401
Despite the potential benefits of their use, engineering geomorphological studies are not widely applied in the UK, Limited applications have been made to landslide assessment and planning of ground investigations. The civil engineer's lack of familiarity with the technique and the geomorphologist's limited understanding of civil engineering design criteria are the two main reasons for the non-optimal application of engineering geomorphology.
Crosshole logging is a promising technique for reservoir characterisation. Pressure noise measurements were made in a field in the Paris Basin at sites ranging from quiet to extremely noisy, with producing wells within 500m of the well containing the hydrophone. The most favourable frequency range to take advantage of low seismic noise levels wave was determined. Part of the borehole seismic noise propagates as tube waves, and noise reduction by array filtering techniques may be expected.
Geophysical techniques See also." 916086, 916128, 916205, 916513 916232 Geothermal exploration using electrical methods Thanassoulas, C Geoexploration V27, N3/4, March 1991, P321-350 As electrical conductivity of ionic conductors responds significantly to temperature change, electrical methods are widely applied in study of geothermal sources. They can be used to examine shallow or deep sites. The geothermal field as a geoelectrical target is discussed, and the variety of methods for its investigation is reviewed. The case of the Milos high enthalpy geothermal field in Greece is presented. The geological setting and exploration program are described, and maps of thermal gradient, resistivity, and self potential illustrated. 916233 Geoelectric profiling Apparao, A Geoexploration V27, N3/4, March 1991, P351-389 Topics investigated by the N G R I over the past 20 years are outlined. The different electrode configurations used are first illustrated. Eight particular problems are examined: surface lateroiog for deep investigation and development of unfocused two electrode systems for surface resistivity profiling, depth of investigation of DC methods, modified pseudo-depth sections, depth of determination against depth of investigation for resistivity and IP methods, resolution of resistivity anomalies over buried conducting dykes, downward continuation of the IP method using point electrodes, effects of surface polarisation in resistivity modelling, and discrimination between minerals using IP. 916234 Quantitative interpretation of three-dimensional mise-a-lamasse data. A case history from Gairloch, northwest Scotland Bowker, A Geoexpioration 1/28, NI, April 1991, PI-22 The mise-a-la-masse method is used where there is a high resistivity contrast between the orebody and the surrounding rock mass. Surface and downhole data are presented from around a massive sulphide orebody in Scotland. Quantitative analysis techniques are presented which include the use of simple interpretational schemes and 3D modelling using the integral equation method. Detailed interpretation of the area is possible,including estimation of the lateral extent of the mineralized blocks, in addition to the location of subsurface faults dividing the mineralization.
916236 Compressional and shear-wave logging in open and cased holes using a multipole tool Chen, S T; Eriksen, E A Geophysics 1/56, N4, April 1991, P550-557 Acoustic logging is generally carried out in open boreholes as it is more efficient to transmit acoustic energy into the formation without casing and cement. Spurious signals including waves travelling along the steel pipe and cement are minimised. Field observations, however, indicate cased hole logging is effective using the multipole tool. The monopole (P wave) and quadrupole (S wave) source-receiver systems operate at frequencies 7-10kHz and 3-7kHz respectively, much lower than the conventional sonic logging tool. The casing can be efficiently penetrated,and formation waves are generally stronger than the unwanted waves.
916237 Application of forward modeling resistivity profiles Radstake, F; Geirnaert, W; Kleinendorst, T W; Terheit, J C Ground Water V29, N1, Jan-Feb 1991, P13-17 A computer program has been developed to generate synthetic response of Wenner or Schlumberger profiles and soundings to 2D subsurface structures. As resistivity response can be calculated in advance, electrode configurations and spacings can be optimised, and a better insight gained into effects of geological structures on size and shape of anomalies in resistivity profiles. The model is demonstrated applied to effects of weathered layer thickness in a granitic environment on sensitivity of electrode arrays and to geological interpretation of a profile from a schistose zone.
916238 Electromagnetic method EM34-3 for subsurface exploration (In French) Borne, V Int Assoc Engng Geol Bull N42, Oct 1990, Pll-20 The EM34-3 conductivity meter measures the apparent resistivity of the earth. The principles are outlined and its operation described. Depth of exploration is dependent on intercoil spacing. Measurements are taken at points along survey lines or on a regular grid pattern. Applications to archeological studies, geophysical prospecting, and geological mapping are illustrated.
© 1991 Pergamon Press plc. Reproduction not permitted
916235 Measurement of borehole seismic noise with hydrophones Chouzenoux, C Geophysics V56. N3, March 1991, P397-401
Despite the potential benefits of their use, engineering geomorphological studies are not widely applied in the UK, Limited applications have been made to landslide assessment and planning of ground investigations. The civil engineer's lack of familiarity with the technique and the geomorphologist's limited understanding of civil engineering design criteria are the two main reasons for the non-optimal application of engineering geomorphology.
Crosshole logging is a promising technique for reservoir characterisation. Pressure noise measurements were made in a field in the Paris Basin at sites ranging from quiet to extremely noisy, with producing wells within 500m of the well containing the hydrophone. The most favourable frequency range to take advantage of low seismic noise levels wave was determined. Part of the borehole seismic noise propagates as tube waves, and noise reduction by array filtering techniques may be expected.
Geophysical techniques See also." 916086, 916128, 916205, 916513 916232 Geothermal exploration using electrical methods Thanassoulas, C Geoexploration V27, N3/4, March 1991, P321-350 As electrical conductivity of ionic conductors responds significantly to temperature change, electrical methods are widely applied in study of geothermal sources. They can be used to examine shallow or deep sites. The geothermal field as a geoelectrical target is discussed, and the variety of methods for its investigation is reviewed. The case of the Milos high enthalpy geothermal field in Greece is presented. The geological setting and exploration program are described, and maps of thermal gradient, resistivity, and self potential illustrated. 916233 Geoelectric profiling Apparao, A Geoexploration V27, N3/4, March 1991, P351-389 Topics investigated by the N G R I over the past 20 years are outlined. The different electrode configurations used are first illustrated. Eight particular problems are examined: surface lateroiog for deep investigation and development of unfocused two electrode systems for surface resistivity profiling, depth of investigation of DC methods, modified pseudo-depth sections, depth of determination against depth of investigation for resistivity and IP methods, resolution of resistivity anomalies over buried conducting dykes, downward continuation of the IP method using point electrodes, effects of surface polarisation in resistivity modelling, and discrimination between minerals using IP. 916234 Quantitative interpretation of three-dimensional mise-a-lamasse data. A case history from Gairloch, northwest Scotland Bowker, A Geoexpioration 1/28, NI, April 1991, PI-22 The mise-a-la-masse method is used where there is a high resistivity contrast between the orebody and the surrounding rock mass. Surface and downhole data are presented from around a massive sulphide orebody in Scotland. Quantitative analysis techniques are presented which include the use of simple interpretational schemes and 3D modelling using the integral equation method. Detailed interpretation of the area is possible,including estimation of the lateral extent of the mineralized blocks, in addition to the location of subsurface faults dividing the mineralization.
916236 Compressional and shear-wave logging in open and cased holes using a multipole tool Chen, S T; Eriksen, E A Geophysics 1/56, N4, April 1991, P550-557 Acoustic logging is generally carried out in open boreholes as it is more efficient to transmit acoustic energy into the formation without casing and cement. Spurious signals including waves travelling along the steel pipe and cement are minimised. Field observations, however, indicate cased hole logging is effective using the multipole tool. The monopole (P wave) and quadrupole (S wave) source-receiver systems operate at frequencies 7-10kHz and 3-7kHz respectively, much lower than the conventional sonic logging tool. The casing can be efficiently penetrated,and formation waves are generally stronger than the unwanted waves.
916237 Application of forward modeling resistivity profiles Radstake, F; Geirnaert, W; Kleinendorst, T W; Terheit, J C Ground Water V29, N1, Jan-Feb 1991, P13-17 A computer program has been developed to generate synthetic response of Wenner or Schlumberger profiles and soundings to 2D subsurface structures. As resistivity response can be calculated in advance, electrode configurations and spacings can be optimised, and a better insight gained into effects of geological structures on size and shape of anomalies in resistivity profiles. The model is demonstrated applied to effects of weathered layer thickness in a granitic environment on sensitivity of electrode arrays and to geological interpretation of a profile from a schistose zone.
916238 Electromagnetic method EM34-3 for subsurface exploration (In French) Borne, V Int Assoc Engng Geol Bull N42, Oct 1990, Pll-20 The EM34-3 conductivity meter measures the apparent resistivity of the earth. The principles are outlined and its operation described. Depth of exploration is dependent on intercoil spacing. Measurements are taken at points along survey lines or on a regular grid pattern. Applications to archeological studies, geophysical prospecting, and geological mapping are illustrated.
© 1991 Pergamon Press plc. Reproduction not permitted