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Comparison between natural fractures and fracture parameters derived from VSP
235A 924233 Vertical gradient of horizontal geomagnetic variations -first results with the Gotlingen burebule magnetometer in the KTBOberpfulz VB Steveling, E; Spitzer, K; Leven, M Sci Drilling V2, N4. 1991, P180-187
Borehole and core logging
A ttiaxial borehole magnetometer has been developed and tested in the KTB-VB pilot borehole. Theory and design are outlined. The main aim was to investigate the skin effect of horizontal magnetic variations through examination of their vertical gradient. Logs were run for up to 14 days at depths 1590-3000m, temperatures to 190 deg C. Depth dependent (well log) and time dependent (fixed depth) logs were run. Using the latter and simultaneous monitoring from the surface, significant results for the skin effect were obtained, although this effect is small, due to the low conductivity of the rocks encountered.
924237 Temperature measurements in geotechnicul studies using lownoise, high-resolution digital techniques Woodbury, A D; Narod, B; Chandra, B; lknnest, J R Can Geotech J V28, NS. Oct 1991, P639-649
924234 Development of a new acoustic borehole imaging tool Schepers, R Sci Drilling V2, N4, 1991, P203-214 The FACSIMILE acoustic borehole scanning tool (Televiewer) was designed for use at high temperatures and pressures. It uses a focused beam in scanning the borehole wall for increased resolution~ improved efficiency and dynamic range, and better performance in irregular holes. Design, data transmission, and data processing are described. It has been tested in the laboratory to 300 deg C and in the field to 230 dog C. Images of fractures and structural features of crystalline and sedimentary rocks and of a perforated casing are illustrated. 924235 Geophysical characterization of soil deformation associated with earth fissures near San Marcial and Deming, New Mexico Haneberg, W C; Reynolds, C B; Reynolds, I B
Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P271-280. Publ [AHS Press: Wallingford. 1991 Shallow seismic reflection over two earth fissures indicates surficiai strata draped over a buried normal fault scarp in one case and over a buried channel (related to groundwater overdraft) in the other. P wave velocity contour plots and gravity profiles indicate anomalies but do not provide much detail. A simple mechanical model for flexure of a compressible elastic layer over steps indicates tensile stress develops along the upper free surface if the steps are wide and along the base of the layer if steps are narrow. It is concluded that geometry of the buried irregularities controls whether fissures propagate upward from depth or downward from the surface. 924236 Sinkhole evolution in alluvial deposits within the central Ebro basin, northeast Spain Benito, G; Perez del Campo, P
Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P323-331. Publ IAHS Press: Wallingford, 1991 A survey was carried out along a 20kin transect in a region with alluvial deposits over Tertiary gypsum. Locations of dolines and depressions indicated in aerial photographs were examined using gravity and GPR methods. Negative gravity anomalies reflect subsurface caves filled with alluvial material. GPR anomalies may indicate caves in the alluvial material which can later form sinkholes by collapse or compaction.
See also: 924116
A digital logging system for use in well logging and hydrogeological investigations is illustrated. Design and theory are presented. Its abilities are demonstrated using the example of the site investigation at the Manitoba Hydro project on the Nelson River. The thermal regime is complex, from permafrost to transient-advective environments. Temperature logging of boreholes was seen to provide information on groundwater flow patterns which ordinary hydrological investigations would have missed.
924238 Inexpensive sampler for obtaining bulk sediment cores Cooper, C M; Schiebe, F R; Ritchie, .I C Environ Geol Water Sci VI8, N2, Sept-Oct 1991o P115-117
A large volume sampler for taking cores up to 100mm diameter and l.Sm long is illustrated. It consists of up to 2m of PVC pipe mounted below an air exhaust-intake valve assembly which automatically closes as the sampler is retrieved. Sample removal is by air pressure. Extension handles can be added such that the instrument can be used in deep water.
924239 Comparison between natural fractures and fracture parameters derived from VSP Kuwahara, Y; lto, H; Kiguchi, T
Geopbys J V107, N3, Dec 1991, P475-483 A comparison is presented between a fracture system resolved by vertical seismic profile (VSP) survey and that seen in a test horehole using an ultrasonic borehole televiewer (BHTV). The borehole examined is 800m deep in welded Tamagawa tuff. BHTV logs of open sections (305-800m) showed two distinct zones with different fracture densities. Anisotropy measured on core samples was too small to be detected by VSP, but the fracture-rich and fracture-poor zones were detected from different Vp/Vs ratios. VSP results are consistent with expected velocity changes due to an isotropic distribution of cracks. A biplanar crack model cannot satisfy VSP results although two sets of parallel fractures are indicated by BHTV.
924240 Multicyfinder control units for prebored hydraulic pre~uremeters. Technical note Smith, T D; Denham, M
Geotecb Test J VI4, N2. June 1991, P212-216 A control unit for pressuremeters is described which can function with a single cylinder for small, low capacity probes or with additional cylinders to increase system capacity for large diameter probes. Comparative results between this device, the Portland State University Pressuremeter control (PUP) unit, and a commercially available (TEXAM) unit using both 32mm and 62mm diameter probes are presented.
© 1992 Pergamon Press Ltd. Reproduction not permitted
Borehole and core logging
A ttiaxial borehole magnetometer has been developed and tested in the KTB-VB pilot borehole. Theory and design are outlined. The main aim was to investigate the skin effect of horizontal magnetic variations through examination of their vertical gradient. Logs were run for up to 14 days at depths 1590-3000m, temperatures to 190 deg C. Depth dependent (well log) and time dependent (fixed depth) logs were run. Using the latter and simultaneous monitoring from the surface, significant results for the skin effect were obtained, although this effect is small, due to the low conductivity of the rocks encountered.
924237 Temperature measurements in geotechnicul studies using lownoise, high-resolution digital techniques Woodbury, A D; Narod, B; Chandra, B; lknnest, J R Can Geotech J V28, NS. Oct 1991, P639-649
924234 Development of a new acoustic borehole imaging tool Schepers, R Sci Drilling V2, N4, 1991, P203-214 The FACSIMILE acoustic borehole scanning tool (Televiewer) was designed for use at high temperatures and pressures. It uses a focused beam in scanning the borehole wall for increased resolution~ improved efficiency and dynamic range, and better performance in irregular holes. Design, data transmission, and data processing are described. It has been tested in the laboratory to 300 deg C and in the field to 230 dog C. Images of fractures and structural features of crystalline and sedimentary rocks and of a perforated casing are illustrated. 924235 Geophysical characterization of soil deformation associated with earth fissures near San Marcial and Deming, New Mexico Haneberg, W C; Reynolds, C B; Reynolds, I B
Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P271-280. Publ [AHS Press: Wallingford. 1991 Shallow seismic reflection over two earth fissures indicates surficiai strata draped over a buried normal fault scarp in one case and over a buried channel (related to groundwater overdraft) in the other. P wave velocity contour plots and gravity profiles indicate anomalies but do not provide much detail. A simple mechanical model for flexure of a compressible elastic layer over steps indicates tensile stress develops along the upper free surface if the steps are wide and along the base of the layer if steps are narrow. It is concluded that geometry of the buried irregularities controls whether fissures propagate upward from depth or downward from the surface. 924236 Sinkhole evolution in alluvial deposits within the central Ebro basin, northeast Spain Benito, G; Perez del Campo, P
Proc 4th International Conference on Land Subsidence, Houston, 12-17 May 1991 P323-331. Publ IAHS Press: Wallingford, 1991 A survey was carried out along a 20kin transect in a region with alluvial deposits over Tertiary gypsum. Locations of dolines and depressions indicated in aerial photographs were examined using gravity and GPR methods. Negative gravity anomalies reflect subsurface caves filled with alluvial material. GPR anomalies may indicate caves in the alluvial material which can later form sinkholes by collapse or compaction.
See also: 924116
A digital logging system for use in well logging and hydrogeological investigations is illustrated. Design and theory are presented. Its abilities are demonstrated using the example of the site investigation at the Manitoba Hydro project on the Nelson River. The thermal regime is complex, from permafrost to transient-advective environments. Temperature logging of boreholes was seen to provide information on groundwater flow patterns which ordinary hydrological investigations would have missed.
924238 Inexpensive sampler for obtaining bulk sediment cores Cooper, C M; Schiebe, F R; Ritchie, .I C Environ Geol Water Sci VI8, N2, Sept-Oct 1991o P115-117
A large volume sampler for taking cores up to 100mm diameter and l.Sm long is illustrated. It consists of up to 2m of PVC pipe mounted below an air exhaust-intake valve assembly which automatically closes as the sampler is retrieved. Sample removal is by air pressure. Extension handles can be added such that the instrument can be used in deep water.
924239 Comparison between natural fractures and fracture parameters derived from VSP Kuwahara, Y; lto, H; Kiguchi, T
Geopbys J V107, N3, Dec 1991, P475-483 A comparison is presented between a fracture system resolved by vertical seismic profile (VSP) survey and that seen in a test horehole using an ultrasonic borehole televiewer (BHTV). The borehole examined is 800m deep in welded Tamagawa tuff. BHTV logs of open sections (305-800m) showed two distinct zones with different fracture densities. Anisotropy measured on core samples was too small to be detected by VSP, but the fracture-rich and fracture-poor zones were detected from different Vp/Vs ratios. VSP results are consistent with expected velocity changes due to an isotropic distribution of cracks. A biplanar crack model cannot satisfy VSP results although two sets of parallel fractures are indicated by BHTV.
924240 Multicyfinder control units for prebored hydraulic pre~uremeters. Technical note Smith, T D; Denham, M
Geotecb Test J VI4, N2. June 1991, P212-216 A control unit for pressuremeters is described which can function with a single cylinder for small, low capacity probes or with additional cylinders to increase system capacity for large diameter probes. Comparative results between this device, the Portland State University Pressuremeter control (PUP) unit, and a commercially available (TEXAM) unit using both 32mm and 62mm diameter probes are presented.
© 1992 Pergamon Press Ltd. Reproduction not permitted