Electricity: measuring and testing – Of geophysical surface or subsurface in situ – By magnetic means
Reexamination Certificate
2000-04-10
2002-09-03
Patidar, Jay (Department: 2862)
Electricity: measuring and testing
Of geophysical surface or subsurface in situ
By magnetic means
C324S368000, C324S244000
Reexamination Certificate
active
06445187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the measurement of magnetic fields. More specifically, this invention relates to the measurement of electrical characteristics of geological formations from within steel cased wells using magnetic circuits.
2. Description of Related Art
Recently the U.S. Department of Energy has sought research proposals on the development of technology to measure the magnetic fields that are outside a steel well casing from inside the steel well casing. A number of partial solutions have been proposed. Generally, these approaches have important limitations, these limitations include: the need for magnetically saturating the well casings, operating only within a few dozen hertz, relying on electromagnetic effects the saturation of the magnetic well casing, a magnetic focusing device, and passing an electromagnetic signal through a conductor, and do not address the use of magnetic sensors suitable for the measurement of the effects of magnetic signals with frequencies above 2 k Hz. Prior approaches also are limited by the electrical skin depth of the conductor, thus as the frequency increases the signal strength decreases. Nor do they use magnetic circuits to direct the magnetic flux directly to the magnetic sensor. Nevertheless, the reader is referred to the following U.S. patent documents for general background material. Each of these patents is hereby incorporated by reference in its entirety for the material contained therein.
U.S. Pat. No. 3,980,881 describes a well logging system of the type utilizing a single conductor cable to provide power from the surface equipment to a down hole subsurface unit and for simultaneously supplying current mode telemetry signals from one or more radiation detectors in the subsurface unit to the surface equipment.
U.S. Pat. No. 3,982,176 describes a well logging system that simultaneously employs a conventional deep induction log and a radio frequency dielectric log to differentiate similar high resistivity fresh water and oil prospective zones.
U.S. Pat. No. 4,071,815 describes a borehole tool for logging the remnant magnetic field of the earth formations surrounding a borehole that includes a coil system having a transmitter, receiver, and nulling coils, a phase-sensitive detector connected across the receiver and nulling coils and a detector system having a pair of axially spaced magnetometers, a pair of counters, an oscillator, a comparator, and a transmitter.
U.S. Pat. No. 4,100,483 describes a dielectric well logging system that includes a logging tool adapted to be passed through a borehole traversing an earth formation.
U.S. Pat. No. 4,110,682 describes a well logging apparatus that uses a narrow wall-engaging pad equipped with an array of vertical electrodes.
U.S. Pat. No. 4,117,394 describes a well logging apparatus that uses a narrow wall-engaging pad equipped with an array of long vertical electrodes.
U.S. Pat. No. 4,130,793 describes a dielectric well logging means that utilizes the signals from a pair of receivers for providing clock pulses corresponding to earth formation dielectric constant.
U.S. Pat. No. 4,205,288 describes an electrical transformer having an electrical winding and a magnetic core having two parallel magnetic circuits having unequal mean lengths.
U.S. Pat. No. 4,319,191 describes a dielectric well logging system that has its coils aligned radially, rather than in alignment, with respect to the longitudinal axis of a sonde, which moves a coil through a borehole.
U.S. Pat. No. 4,320,340 describes a well logging method and apparatus that measures the density of the flux field established inside the casing due to galvanic current flow longitudinally within the casing.
U.S. Pat. No. 4,323,848 describes a method of well logging in petroleum exploration, where a magnetometer is disposed in a well bore to provide indications of the distribution, filimentation, and distortion of a controlled current flow within adjoining strata of interest.
U.S. Pat. No. 4,334,205 describes an electromagnetic device that comprises an annular armature, an inner stator structure defining outwardly extending pole pieces and an outer stator structure defining inwardly extending pole pieces.
U.S. Pat. No. 4,359,687 describes an apparatus for borehole measurements of the induced polarization of earth formations.
U.S. Pat. No. 4,361,808 describes methods and systems for measuring the dielectric constant of an earth formation.
U.S. Pat. No. 4,435,977 describes a method of identifying potential low water cut hydrocarbon producing zones in a sand or sandstone formation by logging the formation to determine its permeability and porosity values and generating from said two sets of values a log of specific surface areas of the formation.
U.S. Pat. No. 4,456,898 describes thermal compensators that comprise at least one metallic alloy in amorphous form, which are especially useful in stabilizing magnetic devices under conditions of changing ambient operating temperature.
U.S. Pat. No. 4,499,422 describes a digital induction resistivity-logging tool for digitally measuring both the in-phase and the quadrature phase components in a receiver signal generated in response to induce eddy currents flowing in the earth's sub-surface formations.
U.S. Pat. No. 4,502,010 describes a method of well logging in petroleum exploration and apparatus for use in the method.
U.S. Pat. No. 4,524,272 describes a method for measuring the location, linear.
flow rate and volume flow rate of undesired water flow behind well casing in a well, that includes irradiating borehole environs with high energy neutrons from a neutron source located in a well tool in the borehole.
U.S. Pat. No. 4,528,508 describes a method and apparatus, which allows remote sensing and in-situ volumetric measurement of liquid petroleum reserves.
U.S. Pat. No. 4,553,097 describes a well logging apparatus and method which can be used as a wireline logging device or technique, and is also suitable for being employed in a logging-while-drilling device.
U.S. Pat. No. 4,560,663 describes a well logging method for identifying the presence of crude petroleum within subsurface earth formations by detecting electron spin resonance signals along a well bore and identifying crude petroleum as the source of those signals by enhancing and/or suppressing the signal by the presence of a chemical.
U.S. Pat. No. 4,609,873 describes a dielectric well logging system that determines dielectric constant and resistivity in formations invaded by water to determine oil and water saturation of the formations.
U.S. Pat. No. 4,631,604 describes a magnetic circuit that is biased by applying signals having noise-like properties to the magnetic circuit.
U.S. Pat. No. 4,652,828 describes well logging techniques for obtaining improved measurements of formation dielectric permitivity, conductivity, and water-filled porosity.
U.S. Pat. Nos. 4,656,422 and 4,792,757 describe oil well logging tools, which make use of nucleons, which are chemically bound to oil and water in geological formations that possess magnetic moments, which align in the earth's magnetic field causing the natural nuclear paramagnetism of the formation.
U.S. Pat. No. 4,692,706 describes a method and apparatus for determining the water saturation of a petroleum reservoir earth formation that includes transmitting electromagnetic energy in the earth formation from within a borehole traversing the earth formation and at least two frequencies within a preferred range of frequencies.
U.S. Pat. No. 4,697,150 describes a well logging instrument for measuring the resistivity of relatively thin formation beds.
U.S. Pat. No. 4,748,415 describes methods and apparatus, which allow induction logging of geological formation through borehole casing.
U.S. Pat. No. 4,820,989 describes methods and apparatus which allow measurement of the resistivity of a geological formation through borehole casing that may be surrounded by brine saturated cement.
U.S. Pat. No. 4,882,542 describes methods and apparatus for me
Montgomery Jerry R.
Montgomery Nathan Rich
Montgomery Sarah Elle
Patidar Jay
Sadler Lloyd W.
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