Patent
Method and apparatus for complex resistivity measurements with elimination of electromagnetic coupling effects
TLDR
In this article, a logging tool with electrodes for introducing a current into a downhole formation and detecting a voltage produced in the formation by the current is presented, where the electrodes are equidistantly spaced but adjustable (either on a single logging tool or as between different logging tools).Abstract:
An apparatus includes a logging tool having electrodes for introducing a current into a downhole formation and for detecting a voltage produced in the formation by the current. The current is provided by a transmitter circuit, and the voltage is received and processed by a receiver circuit including a computer programmed to provide induced polarization and resistivity measurements based on the detected voltage. The electrodes are equidistantly spaced but are adjustable (either on a single logging tool or as between different logging tools) so that various logging runs can be made to obtain different measurements whereby the intrinsic complex resistivity (induced polarization) of formation layers can be suitably resolved. The apparatus also includes a contact resistance measurement circuit for making measurements used by another computer means to determine the contact resistance of each of the electrodes. The contact resistance measurements are used to compute the coupling phase angles for correcting the data at the output of the initial computer means. The logging tool is constructed to reduce water, and therefore electrical, leakage.read more
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Patent
Relative impedance measurement
TL;DR: In this paper, a method for calibrating impedance includes coupling at least first, second, and third electrodes at respective locations to a surface of a body of a subject, and a contact factor is derived that is indicative of the impedance between at least one of the body-surface electrodes and the surface of the subject.
Journal ArticleDOI
A review of some experience with the induced-polarization/resistivity method for hydrocarbon surveys: Successes and limitations
TL;DR: In this paper, the authors developed a geological/geochemical model for the formation of induced polarization and resistivity anomalies over hydrocarbon reservoirs and found that the two main requirements for formation of IP and resistance anomalies, according to this model, are: (1) absence of any thick impermeable seals, such as evaporites, above the reservoir and (2) presence of porous, iron-rich, near-surface host rocks, including clastic rock sequences.
Patent
Geophysical technique for mineral exploration and discrimination based on electromagnetic methods and associated systems
TL;DR: In this article, the authors used remote geophysical observations to determine the parameters of an effective conductivity relaxation model using a composite analytical multi-phase model of the rock formations, which can be used for the discrimination of different components in underground formations, and in this way provide an ability to distinguish between uneconomic mineral deposits and zones of economic mineralization using geophysical remote sensing technology.
Patent
Borehole electric field survey with improved discrimination of subsurface features
Alberto Marsala,Andrew D. Hibbs +1 more
TL;DR: In this paper, the effects of near surface electrical anomalies are detected in the data and removable from the survey data of interest regarding the formations, which can more accurately indicate formation features or properties of interest.
Journal ArticleDOI
Complex resistivity spectra and pore geometry for predictions of reservoir properties in carbonate rocks
TL;DR: In this paper, the authors quantify the complex resistivity spectra (CRS) curves by extracting the slope of both real and imaginary part of complex resistivities in the 10,000-100,000 Hz range.
References
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Patent
Method and apparatus for determining shaliness and oil saturations in earth formations using induced polarization in the frequency domain
TL;DR: In this article, an apparatus for borehole measurements of the induced polarization of earth formations is described, which consists of an induced polarization logger capable of measuring both in-phase and quadrature conductivities in the frequency domain.
Patent
Well logging fiber optic communication system
TL;DR: In this article, the optic source and detector at the surface are mounted on the winch drum to facilitate use of logging cables with fiber optic signal conductors, and electrical signals communicate between the control/processing unit and the optic sources and detectors.
Journal ArticleDOI
Interpretation of buried electrode resistivity data using a layered Earth model
TL;DR: In this paper, a solution for the layered earth problem for a buried current source and a buried receiver is presented, where the model is developed for source and receiver electrodes buried anywhere within a horizontally stratified layered earth containing an arbitrary number of resistivity layers.
Patent
Logging bore holes
TL;DR: In this paper, an electrical logging of bore holes is described. But the present work is directed to the electrical logging and is not related to the work of the present paper, since it is often possible to differentiate between earth formations by making measurements of impedance or resistance between electrodes of several different spreads or configurations when...