Some Effects of Formation Anisotropy on Resistivity Measurements in Boreholes

Kunz, Karl S.; Moran, J. H.

doi:10.1190/1.1438527

Cited by 75 publications

(19 citation statements)

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“…4 is found with the help of a scale transformation of the co-ordinate system, e.g. KuNz and MORAN (1958) and Rush (1967). The co-ordinate system is transformed to a primed system such that x' is defined by x'= x x/~-y tr~ (9) tr y' and z' being defined correspondingly.…”

Section: The Scale Transformationmentioning

confidence: 99%

On the magnetic field and the electrical potential generated by bioelectric sources in an anisotropic volume conductor

Peters

Eliáš

1988

Med. Biol. Eng. Comput.

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Section: The Scale Transformationmentioning

confidence: 99%

On the magnetic field and the electrical potential generated by bioelectric sources in an anisotropic volume conductor

Peters

Eliáš

1988

Med. Biol. Eng. Comput.

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“…The case of an electrode device centered in a borehole perpendicular to the bedding planes of an anisotropic bed also was treated by Kunz and Moran (1958). If the electrode device is eccentered, solutions can be constructed by a simple extension of the methods of Kunz and Moran (1958) and Gianzero and Rau ii977 j.…”

Section: Devices-borehole Effectsmentioning

confidence: 99%

Effects of formation anisotropy on resistivity‐logging measurements

1979

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Some developments in the mathematical analysis of resistivity well-logging measurements in anisotroplc beds are presented. The no-borehole case in which two thick, anixotropic beds meet at a plane interface for bedding planes parallel to the interface has been discussed previously by Kunz and Moran (I 9%). The treatment here is extended to include arbitrary orientation of the bedding planes. Relations are derived for finding the potential distributions in the two media produced by a point current source in one of them. Numerically evaluated apparent-resistivity profiles across the boundary between two anisotropic beds are shown for a normal resistivity-lopgin g device for various conditions of anisotropy and dip.The effect on the responses of a normal device of introducing a borehole perpendicular to the bedding planes of a thick anisotropic bed was also treated by Kunz and Moran (1958). The added effect oC eccentering has been studied following the methods of Gianzero and Rau (1977) but, since the results added nothing of interest. no details are given. For the borehole axis not perpendicular to the bedding planes, no progress can be reported in the analysis.When alternating currents are used, the solutions acquire characteristics dependent on the frequency. Appropriate relations are developed starting from Maxwell' s equations.For electrode devices using alternating current, such as a normal or a LaterologT" . solutions are derived in terms of the vector potential for the case of a borehole penetrating a thick anisotropic bed normal to the bedding planes and for the no-borehole case where the sonde axis is perpendicular to a sequence of beds with all bedding planes parallel to the bed boundaries. Details of the frequency effects are considered only for the case of a homogeneous medium, but indications of the method of solution for heterogeneous media are given. One principal result is that the "paradox of anisotropy" (see Kunz and Moran, 1958) still remains valid.For induction-logging devices, the transmitter-coil sources of the electromagnetic (EM) field are treated as (alternating) magnetic dipoles. When the source-and receiver-coil axes both are oriented perpendicularly to the bedding planes, only the component of resistivity parallel to the bedding planes affects the responses. With the addition of coils oriented parallel to the bedding planes, it is theoretically possible to determine formation dip from the out-of-phase (reactive) voltages in the receiver coils. Analyses arc outlined for a homogeneous medium. for a thin bed. and for borehole cases usually considered.Values of the horizontal and vertical conductivities (and coefficient of anisotropy) can. in principle, be derived from the measured values of the induction-logging conductivity signal and the ou-of-phase signal from the formation. A difficulty with the method is the effect of heterogeneities. When true horizontal conductivity changes across a bed boundary, a plot of computed apparent values of horizontal and vertical resistivities across the b...

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“…Furthermore, a number of isotropic layers can cause pseudoanisotropy. Elongated small particles in the sedimentation such as clay or sand prefer certain directions, which also gives rise to electrical anisotropy (Kunz and Moran, 1958;Rey and Jongmans, 2007). Figure 7 shows a synthetic 2D model.…”

Section: Micro-and Macroanisotropymentioning

confidence: 99%

Resistivity inversion of transversely isotropic media

Yas¹

2018

Turkish J Earth Sci

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IntroductionElectrical conductivity of a geological formation may vary in different directions depending on the formation's properties. This type of directional property of conductivity gives rise to electrical anisotropy (Maillet, 1947). Ignoring the electrical anisotropy of a geological formation or assuming that the formation is isotropic may yield to a misleading interpretation (Nguyen et al., 2007;Wiese et al., 2009;Greenhalgh et al., 2010).Electrical anisotropy detection in the field can be determined by using a square array, since the square array is more sensitive to electrical anisotropy in a geological formation than the most commonly used Schlumberger

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Some Effects of Formation Anisotropy on Resistivity Measurements in Boreholes

Cited by 75 publications

References 1 publication

On the magnetic field and the electrical potential generated by bioelectric sources in an anisotropic volume conductor

On the magnetic field and the electrical potential generated by bioelectric sources in an anisotropic volume conductor

Effects of formation anisotropy on resistivity‐logging measurements

Resistivity inversion of transversely isotropic media

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