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Experimental study of the propagation of flexural waves in an anisotropic borehole model (in Chinese)
SITE INVESTIGATIONS:BOREHOLES characterization of underground waste deposits. This testing procedure uses infrared thcrmography as a primary testing method and ground penetrating radar as a secondary investigation technique. Both technologies have been proven effective in numerous nondestructive testing applications for many years. This method of data fusion has proven to be accurate and cost-effective for gaining detailed information pertaining to subsurface conditions of both large and small sites. (from Authors)
957218 Radiometric, magnetic susceptibility and mineralogical studies in some beach placers of Andhra Prndesh, east coast of India B. N. Rao, Journal - Geological Society of lndia, 43(6), 1994, pp 669-675. Radiometric, magnetic susceptibility and mineralogical studies were carried out on the beach placer deposits in three different coastal regions of Andhra Pradesh. Mona~tc is the only source of radioactivity in the three regions. Iimenite is predominant in Region IH and magnetite in Region I. The Eastern Ghats provenance is the major source of ilmenite and monazite. It is suggested that prospecting for monazite and ilmenite in East Coast of India beaches is best done by a combination of radiometric and magnetic susceptibility techniques. (Author)
Borehole and core logging 957219 Borehole seismic-source radiation pattern in transversely i$otropic media Wenjie Dong & M. N. Toksoz, Geophysics, 60(1), 1995, pp 29-42. Previous discussions on crossweil tomography in anisotropic formations are extended by deriving the radiation patterns of three typical downhole seismic sources (impulsive air gun or dynamite, wall-clamped vertical vibrators, and cylindrical bender) inside a fluid-idled borehole embedded in a transversely isotropic formation. Tests with the radiation patterns show that while the effect of anisotropy on P-waves is moderate, its effect on the S_ wave pattern is significant even for slightly anisotropic formations. One can predict the Swave pattern from the sign of the Thomsen's measure. (from Authors)
333A
relationship between porosity and P-wave transit time. Because clays are composed of fine sheet-like particles, they normally form pores with much smaller aspect ratios than those associated with sand grains. A velocity model for claysand mixtures has been developed in terms of the Kuster and Toksoz effective medium and Gassmann theories. In this model, the total pore space is assumed to consist of two parts: 1) pores associated with sand grains and 2) pores associated with clays (including bound water). The essential feature of the model is the assumption that the geometry of pores associated with sand grains is significantly different from that associated with clays. Because of this, porosity in shales affects elastic compliance differently from porosity in sandstones. (from Authors)
957222 Diffusion theory and the bed boundary response of thermal neutron logging tools G. L. Mathis, Nuclear Geophysics, 8(6), 1994, pp 507-519. Previously, diffusion theory has been applied to a cylindrical borehole geometry to gain insight into the response of thermal neutron logging tools in single porosity formations. However, diffusion theory can also be used to investigate what happens as a tool moves past an interface from one porosity to another. Diffusion theory enables the calculation of fast, epithermal and thermal fluxes as the distance from the detector point to the porosity interface changes. These studies reveal that the transient response of the thermal flux is dependent upon the values and relative positions of the two porosities at the interface. The result is that, in principle, it is not possible to improve the vertical resolution of neutron logs by standard deconvolution techniques. (from Author)
957223 New logging tool identifies permeability in shaley sands J. Lomax & A. Howard, Oil & Gas Journal, 92(51), 1994, pp 104-108. Describes the application of magnetic resonance imaging logging (MRIL) for identifying permeable zones in interbedded shales and sandy shales in the Monument Butte field in Utah, USA. The technique uses the phenomenon of nuclear magnetic resonance to accurately measure free fluid, irreducible water, and effective porosity. Permeability measurement is derived from these. Two zones of interest were investigated with the tool. Based on the MRIL interpretation, effective hydraulic fracturing of these zones was carried out. (LM.McLaughlin)
957220 Experimental study of the propagation of flexural waves in an anisotropic berehole model (in Chinese) Zhu Zhen-Ya, Cheng Chuan-Han & M. N. Toksoz, Acta Geophysical Sinica, 37(6), 1994, pp 811-818.
957224 Fractional Levy motion as a model for spatial variability in sedimentary rock S. Painter & L. Paterson, Geophysical Research Letters, 21(25), 1994, pp 2857-2860.
The basic principles and main properties of flexnral waves propagating in a borehole are introduced. In order to simulate the hard and soft formation boreholes, measurements are performed with mono/dipole transducers in borehole models made of aluminum and lucite, respectively. Experimental results are compared with the theoretical dispersion characterstics. The experimental results show that dipole acoustic well logging could be an effective means for surveying a formation's anisotropy. (English summary)
A new approach to the modefing of spatial variability in sedimentary formations is introduced. This approach avoids the assumption of Gaussian behavior, Specifically, borehole measurements of physical properties of sedimentary rock from contrasting geological settings axe shown to have a statistical character consistent with fractional Levy motion. Successive increments in the measurement sequences are accurately modeled as having Levy-stable distributions. In addition to reproducing the statistical properties of well logs, the new model also mimics the most striking visual features of sedimentary formations. (from Authors)
957221 A new velocity model for clay-sand mixtures Shiyu Xu & R. E. White, Geophysical Prospecting, 43(1), 1995, pp 91-118. None of the standard porosity-velocity models is saUsfactory for interpreting well-logging data over a broad depth range. Clays in the section are the usual source of the difficulty through the bias and scatter that they introduce into the
957225 Geology along the Trans-Missouri River Tunnel, Kansas City, Missouri g. J. Gentile, R. L. Moberly & S. K. Barnes, Bulletin Association of Engineering Geologists, 31(4), 1994, pp 483504.
957218 Radiometric, magnetic susceptibility and mineralogical studies in some beach placers of Andhra Prndesh, east coast of India B. N. Rao, Journal - Geological Society of lndia, 43(6), 1994, pp 669-675. Radiometric, magnetic susceptibility and mineralogical studies were carried out on the beach placer deposits in three different coastal regions of Andhra Pradesh. Mona~tc is the only source of radioactivity in the three regions. Iimenite is predominant in Region IH and magnetite in Region I. The Eastern Ghats provenance is the major source of ilmenite and monazite. It is suggested that prospecting for monazite and ilmenite in East Coast of India beaches is best done by a combination of radiometric and magnetic susceptibility techniques. (Author)
Borehole and core logging 957219 Borehole seismic-source radiation pattern in transversely i$otropic media Wenjie Dong & M. N. Toksoz, Geophysics, 60(1), 1995, pp 29-42. Previous discussions on crossweil tomography in anisotropic formations are extended by deriving the radiation patterns of three typical downhole seismic sources (impulsive air gun or dynamite, wall-clamped vertical vibrators, and cylindrical bender) inside a fluid-idled borehole embedded in a transversely isotropic formation. Tests with the radiation patterns show that while the effect of anisotropy on P-waves is moderate, its effect on the S_ wave pattern is significant even for slightly anisotropic formations. One can predict the Swave pattern from the sign of the Thomsen's measure. (from Authors)
333A
relationship between porosity and P-wave transit time. Because clays are composed of fine sheet-like particles, they normally form pores with much smaller aspect ratios than those associated with sand grains. A velocity model for claysand mixtures has been developed in terms of the Kuster and Toksoz effective medium and Gassmann theories. In this model, the total pore space is assumed to consist of two parts: 1) pores associated with sand grains and 2) pores associated with clays (including bound water). The essential feature of the model is the assumption that the geometry of pores associated with sand grains is significantly different from that associated with clays. Because of this, porosity in shales affects elastic compliance differently from porosity in sandstones. (from Authors)
957222 Diffusion theory and the bed boundary response of thermal neutron logging tools G. L. Mathis, Nuclear Geophysics, 8(6), 1994, pp 507-519. Previously, diffusion theory has been applied to a cylindrical borehole geometry to gain insight into the response of thermal neutron logging tools in single porosity formations. However, diffusion theory can also be used to investigate what happens as a tool moves past an interface from one porosity to another. Diffusion theory enables the calculation of fast, epithermal and thermal fluxes as the distance from the detector point to the porosity interface changes. These studies reveal that the transient response of the thermal flux is dependent upon the values and relative positions of the two porosities at the interface. The result is that, in principle, it is not possible to improve the vertical resolution of neutron logs by standard deconvolution techniques. (from Author)
957223 New logging tool identifies permeability in shaley sands J. Lomax & A. Howard, Oil & Gas Journal, 92(51), 1994, pp 104-108. Describes the application of magnetic resonance imaging logging (MRIL) for identifying permeable zones in interbedded shales and sandy shales in the Monument Butte field in Utah, USA. The technique uses the phenomenon of nuclear magnetic resonance to accurately measure free fluid, irreducible water, and effective porosity. Permeability measurement is derived from these. Two zones of interest were investigated with the tool. Based on the MRIL interpretation, effective hydraulic fracturing of these zones was carried out. (LM.McLaughlin)
957220 Experimental study of the propagation of flexural waves in an anisotropic berehole model (in Chinese) Zhu Zhen-Ya, Cheng Chuan-Han & M. N. Toksoz, Acta Geophysical Sinica, 37(6), 1994, pp 811-818.
957224 Fractional Levy motion as a model for spatial variability in sedimentary rock S. Painter & L. Paterson, Geophysical Research Letters, 21(25), 1994, pp 2857-2860.
The basic principles and main properties of flexnral waves propagating in a borehole are introduced. In order to simulate the hard and soft formation boreholes, measurements are performed with mono/dipole transducers in borehole models made of aluminum and lucite, respectively. Experimental results are compared with the theoretical dispersion characterstics. The experimental results show that dipole acoustic well logging could be an effective means for surveying a formation's anisotropy. (English summary)
A new approach to the modefing of spatial variability in sedimentary formations is introduced. This approach avoids the assumption of Gaussian behavior, Specifically, borehole measurements of physical properties of sedimentary rock from contrasting geological settings axe shown to have a statistical character consistent with fractional Levy motion. Successive increments in the measurement sequences are accurately modeled as having Levy-stable distributions. In addition to reproducing the statistical properties of well logs, the new model also mimics the most striking visual features of sedimentary formations. (from Authors)
957221 A new velocity model for clay-sand mixtures Shiyu Xu & R. E. White, Geophysical Prospecting, 43(1), 1995, pp 91-118. None of the standard porosity-velocity models is saUsfactory for interpreting well-logging data over a broad depth range. Clays in the section are the usual source of the difficulty through the bias and scatter that they introduce into the
957225 Geology along the Trans-Missouri River Tunnel, Kansas City, Missouri g. J. Gentile, R. L. Moberly & S. K. Barnes, Bulletin Association of Engineering Geologists, 31(4), 1994, pp 483504.