- Email: [email protected]
Engineering geomorphological mapping for cliff stability
29A
Proc International Chalk Symposium, Brighton, 4-7
921222 Mapping of seawater intrusion into the coastal aquifer of Israel by the time domain electromagnetic method Goldman, M; Gilad, D; Ronen, A; Melloui, A
September 1989 P545-549. Publ London: Thomas Telford,
Geoexploratlon V28, N2, July 1991. P153-174
921218 Engineering geomorphological mapping for cliff stability Birch, G P
1990 In order to assist the Channel Tunnel builders in the planning of permanent works on the lower Shakespeare reclamation site, a photogeomorphological mapping study of the cliff was conducted. The study was aimed at analysing the cliff processes and the present stability. The cliff processes, which include weathering, toppling failures, wedge and plane failures, and shearing and mass slides, lead to slope retreat. Details of the study and location of the events and predictions of future behaviour are presented.
An extensive survey for quantitative examination of the capability of the TDEM to map saltwater intrusion into a coastal aquifer was carried out in summer 1989. To acquire a statistically significant data set, over 100 TDEM stations were established. The method, survey stages, and output are described. Of 31 TDEM measurements indicating intrusion, 21 showed good agreement with borehole data, 5 showed fair agreement.
921223 Seismic analysis of Black Creek and Wabumun salt collapse features, western Canadian sedimentary basin Andersen, N L; Brown, R J
Geophysics V56, N5, May 1991, P618-627
Geophysical techniques 921219 Computer simulation of crosswell seismic propagation and determination of elastic parameters. Note Singh, R P; Chandra, S; Jha, A K; Singh, Y P
Can Geotech J V28. N2, April 1991, P309-315 Computer simulations to examine the potential of the combined borehole to borehole and borehole to surface configuration for mapping the subsurface are described. The synthetic data were inverted using the ray projection technique RAYPT. Size, shape, and orientation of anomalies can be delineated rapidly and economically.
Both the Devonian salts considered are interbedded with predominantly carbonate sequences, and both have been extensively leached. Discontinuous salt remnants of variable thickness and areal extent are found. These remnants and their collapse features are often associated with structural or stratigraphic traps, which in turn are often associated with hydrocarbon deposits. Seismic methods have been used to map the Black Creek and Wabumun salts. Prospective areas for hydrocarbon exploration are delineated, and the likelihood of remnant salt being interpreted as reef or fault structures is minimised. 921224 Use of drill-bit energy as a downhole seismic source Rector, J W; Marion, B P
Geophysics V56, N5, May 1991, P628-634 921220 Detecting voids in a 0.6m coal seam, 7m deep, using seismic reflection Miller, R D; Steeples, D W
Geoexploration V28, N2, July 1991, PI09-119 High resolution P wave reflection seismics was used to evaluate the risk of formation of an active sinkhole in an area underlain by abandoned coal workings. Water filled cavities which lead to sinkholes are found in the 7m deep, 0.6m thick coal seam. The remnants of room and pillar mining could be clearly interpreted on stack seismic sections. The apparently active sinkhole is thought to result from erosion rather than reactivated subsidence.
921221 Delineation of a resistive drainage channel by EM conductivity survey Ogilvy, R D; Cuadra, A; Jackson, P D; Cuellar, V
Geoexploration V28. N2, July 1991, P139-152 EM conductivity surveys were carried out over an air-filled drainage gallery set at the interface between lower hard clay and upper gravel, boulder beds, and sandy clay. No measurable response was found from the gallery, but the desaturated drainage channel above the gallery was delineated. One dimensional modelling confirms that a resistive layer in a conductive host is harder to detect than a target of moderately higher conductivity, using the given survey method. Full resolution capability can only be examined by more complex modelling.
A new wellbore seismic technique is described where the drill bit acts as a seismic source and the receiver is on the surface, the reverse of conventional VSP layout. No downhole instrumentation is necessary, and drilling can continue without interference whilst data is continuously processed. Interchange of source and receiver positions improves the efficiency of recording multioffset surveys for imaging a 3D data volume around the borehole. Data processing is discussed. Test results indicate the processed drill bit data are comparable to conventional VSP data.
921225 Thin-layer fracture density Spencer, T W; Chi, H C
Geophysics V56, N6. June 1991, P833-843 Anisotropy determination by traveltime analysis in thinly layered sequences is made difficult by interference between reflections from the layers. An alternative method for determining anisotropy based on hodogram analysis is presented. If the layer is a reservoir and the anisotropy is due to a single oriented set of fractures, the method provides sufficient information to determine lateral changes in fracture density in the reservoir.
921226 Application of ground-penetrating-radar methods in hydrogeologic studies Beres, M; Haeni, F P
Ground Water V29, N3, May-June 1991, P375-386 GPR was applied to study stratified drift deposits in Connecticut. Traverses across a well field, a sand and gravel pit, farm land overlying a potential aquifer, a river, and a lake are described. Penetration depth varied from about 6m in fine
© 1992 Pergamon Press pie. Reproduction not permitted
Proc International Chalk Symposium, Brighton, 4-7
921222 Mapping of seawater intrusion into the coastal aquifer of Israel by the time domain electromagnetic method Goldman, M; Gilad, D; Ronen, A; Melloui, A
September 1989 P545-549. Publ London: Thomas Telford,
Geoexploratlon V28, N2, July 1991. P153-174
921218 Engineering geomorphological mapping for cliff stability Birch, G P
1990 In order to assist the Channel Tunnel builders in the planning of permanent works on the lower Shakespeare reclamation site, a photogeomorphological mapping study of the cliff was conducted. The study was aimed at analysing the cliff processes and the present stability. The cliff processes, which include weathering, toppling failures, wedge and plane failures, and shearing and mass slides, lead to slope retreat. Details of the study and location of the events and predictions of future behaviour are presented.
An extensive survey for quantitative examination of the capability of the TDEM to map saltwater intrusion into a coastal aquifer was carried out in summer 1989. To acquire a statistically significant data set, over 100 TDEM stations were established. The method, survey stages, and output are described. Of 31 TDEM measurements indicating intrusion, 21 showed good agreement with borehole data, 5 showed fair agreement.
921223 Seismic analysis of Black Creek and Wabumun salt collapse features, western Canadian sedimentary basin Andersen, N L; Brown, R J
Geophysics V56, N5, May 1991, P618-627
Geophysical techniques 921219 Computer simulation of crosswell seismic propagation and determination of elastic parameters. Note Singh, R P; Chandra, S; Jha, A K; Singh, Y P
Can Geotech J V28. N2, April 1991, P309-315 Computer simulations to examine the potential of the combined borehole to borehole and borehole to surface configuration for mapping the subsurface are described. The synthetic data were inverted using the ray projection technique RAYPT. Size, shape, and orientation of anomalies can be delineated rapidly and economically.
Both the Devonian salts considered are interbedded with predominantly carbonate sequences, and both have been extensively leached. Discontinuous salt remnants of variable thickness and areal extent are found. These remnants and their collapse features are often associated with structural or stratigraphic traps, which in turn are often associated with hydrocarbon deposits. Seismic methods have been used to map the Black Creek and Wabumun salts. Prospective areas for hydrocarbon exploration are delineated, and the likelihood of remnant salt being interpreted as reef or fault structures is minimised. 921224 Use of drill-bit energy as a downhole seismic source Rector, J W; Marion, B P
Geophysics V56, N5, May 1991, P628-634 921220 Detecting voids in a 0.6m coal seam, 7m deep, using seismic reflection Miller, R D; Steeples, D W
Geoexploration V28, N2, July 1991, PI09-119 High resolution P wave reflection seismics was used to evaluate the risk of formation of an active sinkhole in an area underlain by abandoned coal workings. Water filled cavities which lead to sinkholes are found in the 7m deep, 0.6m thick coal seam. The remnants of room and pillar mining could be clearly interpreted on stack seismic sections. The apparently active sinkhole is thought to result from erosion rather than reactivated subsidence.
921221 Delineation of a resistive drainage channel by EM conductivity survey Ogilvy, R D; Cuadra, A; Jackson, P D; Cuellar, V
Geoexploration V28. N2, July 1991, P139-152 EM conductivity surveys were carried out over an air-filled drainage gallery set at the interface between lower hard clay and upper gravel, boulder beds, and sandy clay. No measurable response was found from the gallery, but the desaturated drainage channel above the gallery was delineated. One dimensional modelling confirms that a resistive layer in a conductive host is harder to detect than a target of moderately higher conductivity, using the given survey method. Full resolution capability can only be examined by more complex modelling.
A new wellbore seismic technique is described where the drill bit acts as a seismic source and the receiver is on the surface, the reverse of conventional VSP layout. No downhole instrumentation is necessary, and drilling can continue without interference whilst data is continuously processed. Interchange of source and receiver positions improves the efficiency of recording multioffset surveys for imaging a 3D data volume around the borehole. Data processing is discussed. Test results indicate the processed drill bit data are comparable to conventional VSP data.
921225 Thin-layer fracture density Spencer, T W; Chi, H C
Geophysics V56, N6. June 1991, P833-843 Anisotropy determination by traveltime analysis in thinly layered sequences is made difficult by interference between reflections from the layers. An alternative method for determining anisotropy based on hodogram analysis is presented. If the layer is a reservoir and the anisotropy is due to a single oriented set of fractures, the method provides sufficient information to determine lateral changes in fracture density in the reservoir.
921226 Application of ground-penetrating-radar methods in hydrogeologic studies Beres, M; Haeni, F P
Ground Water V29, N3, May-June 1991, P375-386 GPR was applied to study stratified drift deposits in Connecticut. Traverses across a well field, a sand and gravel pit, farm land overlying a potential aquifer, a river, and a lake are described. Penetration depth varied from about 6m in fine
© 1992 Pergamon Press pie. Reproduction not permitted