tensor csamt studies at the buchans mine in central newfoundland : boerner, de; ]wright, ja;...

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295A 935209 Borebole geophysics in environmental applications Mwenifumbo, C J CIM Bull 1/86, N966, Jan 1993, P43-49 Prevention of pollution of groundwater as a result of contami- nation from waste disposal requires careful siting of hazardous waste dumps. Information on subsurface hydrogeology can be obtained using borehole geophysical techniques to map lithol- ogy, porosity, and fractures. The extent and changes in site pollution can be measured using a variety of borehole, crosshole, and surface-to-borehole methods. The range of field techniques available and areas where they are most suitably applied are outlined. 935210 Environmental applications of surface and airborne geophysics in mining King, A; Pesowski, M CIM Bull V86, N966, Jan 1993, P58-67 The physical properties of the subsurface may be altered by pollution or contamination, and this should be investigated before drilling and sampling. Ground conductivity measure- ments can be used to monitor chemical pollution, magnetic surveys can detect buried metallic objects, and radiometric techniques can be used to map radioactive mine waste. Geo- physical techniques can characterise site geology and assist in mine planning and development. Examples of use of these methods are presented, with particular interest in acid mine drainage. 935211 Shallow seismic reflection in a mine gallery Frappa, M; Molinier, C Engng Geol 1/33, N3, Feb 1993, P201-208 In-mine seismic reflection surveying has been used to investi- gate sulphide mineral deposits beneath the main access gallery of a copper mine in France. The technique has been adapted to cope with the thin mineral-bearing layers, varying thickness of overlying strata, and inaccessible rock faces. Four-fold mul- tiple coverage was used. A model was developed, using syn- thetic data, to allow evaluation of optimal offset. Deconvolution and application of complex traces analysis allows degree of continuity of the mineral horizon to be assessed. 935212 Induced gravity anomalies and rock-burst risk in coal mines: a case history Casten, U; Fajklewicz, Z Geophys Prospect V41, N1, Jan 1993, P1-13 The dilatancy phenomenon in brittle rocks forms the basis of the method of predicting rockbursts using microgravity mea- surement. Induced gravity anomalies on the level of the Dick- ebank seam and in the Sonnenschein seam of the Rabod coal mine, Germany, are described. In the first, the effect of two approaching longwalls on a previously mined seam and in the measurement gallery are illustrated. In the second case, the presence of a remnant pillar caused the largest gravity gradi- ents. Gravity anomalies are seen to group together at known hazard zones, indicating the gravity surveying method may have applications in rockburst prediction. 935213 Viscoelastic seismic responses of 2D reservoir models Kang, I B; McMechan, G A Geophys Prospect V41, N2, Feb 1993, P149-163 Viscoelastic effects can be accurately simulated in time domain numerical computation of seismic response of reservoirs through the use of relaxation mechanisms. Synthetic seismo- grams can be produced for models with arbitrary spatial varia- tions in P and S wave velocity and quality factor and in density. Examples applicable to reservoir exploration, evalua- tion, and monitoring are presented. Inaccuracies arising from assumption of only elastic behaviour are illustrated. 935214 Borehole Stoneley wave propagation across permeable structures Tang, X M; Cheng, C H Geophys Prospect V41, N2, Feb 1993, P165-187 The Stoneley (tube) wave is of low velocity and large ampli- tude and is sensitive to variations in density, moduli, and (in particular) permeability of the formation. A theory for Stoneley wave interaction with the borehole structure is devel- oped and used to analyse propagation across a single fracture, a permeable porous layer, and a permeable fracture zone. Attenuation is observed across high permeability zones. On the basis of this work, a method to characterize the fluid trans- port properties of a permeable fracture zone is developed. 935215 Examples of resolution improvement in geoelectrical soundings applied to groundwater investigations Sandberg, S K Gcophys Prospect V41, N2, Feb 1993, P207-227 Geoelectrical methods (resistivity, IP, TEM) are commonly used in groundwater investigations. Three typical objectives are mapping units with low resistivity contrast, mapping depth to interfaces between conductive and resistive layers, and resolving thickness of thin, relatively conductive layers. Using data from two field cases and one simulation, it is shown simultaneous inversion of simple IP data with conventional resistivity and resistivity-TEM data sets results in greatly improved parameter resolution. 935216 Tensor CSAMT studies at the Buchans Mine in central Newfoundland Boerner, D E; Wright, J A; Thurlow, J G; Reed, L E Geophysics I"58, NI, Jan 1993, P12-19 Novel application of the tensor controlled audio-magnetotel- luric method to study an existing mine is described. Because of strong scattering of electric fields, it was necessary to use the length of the major axes of electrical and magnetic field polari- zation ellipses and the vertical magnetic field as data. Inver- sion of these data suggests an essentially two layered earth with an increase in resistivity between depths 1000-1400m, interpreted as coincident with the Powerline Fault, a floor thrust of a duplex structure. 935217 Comparison of high-resolution wax-embedded and pneumatically coupled borehole seismic detectors Owen, T E; Parra, J O Geophysics 1/58, N1, Jan 1993, P141-153 Borehole seismic detectors have been developed using the design philosophy in which optimum coupling is achieved when the probe takes the conformal shape of the borehole, has © 1993 Pergamon Press Ltd. Reproduction not permitted

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Page 1: Tensor CSAMT studies at the Buchans mine in central Newfoundland : Boerner, DE; ]Wright, JA; Thurlow, JG; Reed, LE GeophysicsV58, N1, Jan 1993, P12–19

295A

935209 Borebole geophysics in environmental applications Mwenifumbo, C J CIM Bull 1/86, N966, Jan 1993, P43-49

Prevention of pollution of groundwater as a result of contami- nation from waste disposal requires careful siting of hazardous waste dumps. Information on subsurface hydrogeology can be obtained using borehole geophysical techniques to map lithol- ogy, porosity, and fractures. The extent and changes in site pollution can be measured using a variety of borehole, crosshole, and surface-to-borehole methods. The range of field techniques available and areas where they are most suitably applied are outlined.

935210 Environmental applications of surface and airborne geophysics in mining King, A; Pesowski, M CIM Bull V86, N966, Jan 1993, P58-67

The physical properties of the subsurface may be altered by pollution or contamination, and this should be investigated before drilling and sampling. Ground conductivity measure- ments can be used to monitor chemical pollution, magnetic surveys can detect buried metallic objects, and radiometric techniques can be used to map radioactive mine waste. Geo- physical techniques can characterise site geology and assist in mine planning and development. Examples of use of these methods are presented, with particular interest in acid mine drainage.

935211 Shallow seismic reflection in a mine gallery Frappa, M; Molinier, C Engng Geol 1/33, N3, Feb 1993, P201-208

In-mine seismic reflection surveying has been used to investi- gate sulphide mineral deposits beneath the main access gallery of a copper mine in France. The technique has been adapted to cope with the thin mineral-bearing layers, varying thickness of overlying strata, and inaccessible rock faces. Four-fold mul- tiple coverage was used. A model was developed, using syn- thetic data, to allow evaluation of optimal offset. Deconvolution and application of complex traces analysis allows degree of continuity of the mineral horizon to be assessed.

935212 Induced gravity anomalies and rock-burst risk in coal mines: a case history Casten, U; Fajklewicz, Z Geophys Prospect V41, N1, Jan 1993, P1-13

The dilatancy phenomenon in brittle rocks forms the basis of the method of predicting rockbursts using microgravity mea- surement. Induced gravity anomalies on the level of the Dick- ebank seam and in the Sonnenschein seam of the Rabod coal mine, Germany, are described. In the first, the effect of two approaching longwalls on a previously mined seam and in the measurement gallery are illustrated. In the second case, the presence of a remnant pillar caused the largest gravity gradi- ents. Gravity anomalies are seen to group together at known hazard zones, indicating the gravity surveying method may have applications in rockburst prediction.

935213 Viscoelastic seismic responses of 2D reservoir models Kang, I B; McMechan, G A Geophys Prospect V41, N2, Feb 1993, P149-163

Viscoelastic effects can be accurately simulated in time domain numerical computation of seismic response of reservoirs through the use of relaxation mechanisms. Synthetic seismo- grams can be produced for models with arbitrary spatial varia- tions in P and S wave velocity and quality factor and in density. Examples applicable to reservoir exploration, evalua- tion, and monitoring are presented. Inaccuracies arising from assumption of only elastic behaviour are illustrated.

935214 Borehole Stoneley wave propagation across permeable structures Tang, X M; Cheng, C H Geophys Prospect V41, N2, Feb 1993, P165-187

The Stoneley (tube) wave is of low velocity and large ampli- tude and is sensitive to variations in density, moduli, and (in particular) permeability of the formation. A theory for Stoneley wave interaction with the borehole structure is devel- oped and used to analyse propagation across a single fracture, a permeable porous layer, and a permeable fracture zone. Attenuation is observed across high permeability zones. On the basis of this work, a method to characterize the fluid trans- port properties of a permeable fracture zone is developed.

935215 Examples of resolution improvement in geoelectrical soundings applied to groundwater investigations Sandberg, S K Gcophys Prospect V41, N2, Feb 1993, P207-227

Geoelectrical methods (resistivity, IP, TEM) are commonly used in groundwater investigations. Three typical objectives are mapping units with low resistivity contrast, mapping depth to interfaces between conductive and resistive layers, and resolving thickness of thin, relatively conductive layers. Using data from two field cases and one simulation, it is shown simultaneous inversion of simple IP data with conventional resistivity and resistivity-TEM data sets results in greatly improved parameter resolution.

935216 Tensor CSAMT studies at the Buchans Mine in central Newfoundland Boerner, D E; Wright, J A; Thurlow, J G; Reed, L E Geophysics I"58, NI, Jan 1993, P12-19

Novel application of the tensor controlled audio-magnetotel- luric method to study an existing mine is described. Because of strong scattering of electric fields, it was necessary to use the length of the major axes of electrical and magnetic field polari- zation ellipses and the vertical magnetic field as data. Inver- sion of these data suggests an essentially two layered earth with an increase in resistivity between depths 1000-1400m, interpreted as coincident with the Powerline Fault, a floor thrust of a duplex structure.

935217 Comparison of high-resolution wax-embedded and pneumatically coupled borehole seismic detectors Owen, T E; Parra, J O Geophysics 1/58, N1, Jan 1993, P141-153

Borehole seismic detectors have been developed using the design philosophy in which optimum coupling is achieved when the probe takes the conformal shape of the borehole, has

© 1993 Pergamon Press Ltd. Reproduction not permitted

Page 2: Tensor CSAMT studies at the Buchans mine in central Newfoundland : Boerner, DE; ]Wright, JA; Thurlow, JG; Reed, LE GeophysicsV58, N1, Jan 1993, P12–19

296A

mass density close to that of the formation, and is rigid. Ide- ally-coupled wax-embedded detectors have been successfully tested in the laboratory and the field. The pneumatically cou- pled detector has been evaluated in more practical field condi- tions in a shallow reverse VSP experiment. The high quality responses of both detectors and their differences are discussed.

The mutual position of boreholes is represented in the map- ping plane as a network of triangles determined by the lengths 1. It is suitable for layout of grouting, ground freezing or blast- ing drillholes. Field data are illustrated which compare results from this method with data from an angle recording instrument.

935218 Vibroseis reflection seismic survey at the Buehans Mine in central Newfoundland Spencer, C; Thuriow, G; Wright, J; White, D; Carroll, P; Mikereit, B; Reed, L Geophysics I"58, NI, Jan 1993, P154-166

The first major seismic reflection survey at a mine in North America is reported, Conventional high-stack fold reflection seismic techniques imaged the fault structures associated with the volcanogenic massive sulphide orebodies, despite these being locally of steep dip and giving records with low signal- to-noise ratios. Experimental configurations and details are given. Comparisons are made between the new sections and those from conventional borehole and seismic techniques. Suf- ficient new information on the nature of thrust faulting at the mine was obtained to influence exploration plans.

935219 Testing Fonrnier's method of finding water table from self potential Birch, F S Ground Water V31, N1, Jan-Feb 1993. P50-56

Field testing of the method of estimating the SP anomalies thought to be caused by the water table configuration is described. The SP method is briefly reviewed and details of the calculation given. Satisfactory results, confirmed by indepen- dent contemporaneous measurements, were obtained at 5 of the 6 New Hampshire sites. Apparent coupling coefficients were 0.95-4mV/m for till sites and -16 and -17mV/m for sand and gravel respectively. It is not possible to determine water table elevations from SP surveys alone, because of non-uni- queness, but the technique may be useful in location of regions of geologic heterogeneity.

935220 Reservoir characterisation applying high-resolution seismic profiling, Rabis Creek, Denmark Olsen, H; Ploug, C; Nielsen, U; Sorensen, K Ground Water V31, N1, Jan-Feb 1993, P84-90

Onshore reflection seismics was used to study a presumed homogeneous outwash sand plain. A 1350m long seismic sec- tion was produced, with high resolution data to 160m depth along most of the length. Local reflections from depths as great as 400m were recorded. The seismic data were correlated with electrical resistivity logs. Three distinguishable seismic sequences of unconsolidated sediments were indicated, con- trary to expectations. Combined with seismic facies and sequence analysis, seismic profiling provides a useful supple- ment to traditional boring and logging methods.

935221 Magnetic induction applied to borehole deviation problems Sedlak, V Int J Geotech Geol Engng Vll, N1, March 1993, P25-35

An approach to mapping the mutual positions of boreholes using magnetic methods is presented. It is based on measure- ment of the component of magnetic induction (B) of a gener- ated magnetic field. Using the measured value of the field of a rod magnet it is possible to determine the distance (1) between the source of this field and the sensor of the magnetometer.

935222 Tomographic imaging of P and S wave velocity structure beneath northeastern Japan Zhao, D; Hasegawa, A; Horiuchi, S J Geophys Res V97, NBI3, Dec' 1992, P19909-19928

Seismic body wave tomography has now been developed such that 3D images of the earth's interior can be obtained by processing P and S wave data from earthquakes. The mathe- matical techniques used to image the structure beneath Japan from waves generated by 470 shallow to intermediate depth earthquakes and the results obtained are described. Imaging depths of 200km are possible. Correlations between the tomographic images and observed seismicity are discussed.

935223 Fault proximity surveys in coal using guided seismic waves - numerical modelling Greenhalgh, S A; Cao, S; Mason, I M; Pant, D R Pure Appi Geophys V139, N2, 1992, P215-239

A variation of the in-seam seismic techniques used to image faults in coal seams is presented, a hybrid surface-under- ground procedure. The Walkaway VSP Waveguide Technique uses a surface source array and in-seam and borehole detec- tors. Finite difference and physical modelling results show small faults generate recognisable diffraction patterns by con- verting incident waves to in-seam channel waves. The method may be developed into a relatively inexpensive approach to fault mapping for coal mines.

935224 Characteristic periods of the induction arrows for a conductive-resistive vertical interface - a numerical model study Agarwal, A K; Dosso, H W Phys Earth Planet Inter V76, NIl2, Feb 1993, P67-74

Electromagnetic induction profiles over conductive plates of semi-infinite and finite widths in uniform and layered resistive hosts have been studied numerically. The spatial dependence of the characteristic periods of the induction arrows along the profile has been investigated. It is demonstrated that these characteristic periods can, in principle, be used to delineate the location of the conductive-resistive interface and to provide information on dimensions, depth, and conductivity of the conductive body, if conductivity of the host and substratum are known.

935225 Estimation of mechanical rock properties using wireline geophysical measurements Wade, L; Wang, R; Horton, M A Trans lnst Min Metall (Sect A Min lnd) V102, Jan-April 1993, PA31-A36

Geophysical techniques can provide geomechanical data with- out the need for expensive sampling, which may also cause damage or disturbance. 151 samples were obtained from a borehole at a Staffordshire colliery which has been compre- hensively geophysically logged. UCS can be reasonably pre- dicted from field sonic travel time measurements, Young's modulus with a lower degree of certainty. Using multivariate regression analysis of downhole travel time, UCS, depth, and

© 1993 Pergamon Press Ltd. Reproduction not permitted