Methods and apparatus for evaluating downhole conditions through fluid sensing
First Claim
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1. An assembly, comprising:
- a body member forming a portion of a casing string disposed within a borehole defined by formation sidewalls to define an annulus between the casing string and the formation sidewalls;
a first fluid sensing component supported by the body member, the first fluid sensing component including a first plurality of electrodes attached over an outer surface of the casing string and arranged as one or more pairs of electrodes between each of which impedance of fluid in the annulus is measured, wherein for each of the one or more pairs of electrodes, one of the electrodes is offset from the other electrode in a direction longitudinally parallel to the casing string; and
an electronics assembly operably coupled to the first fluid sensing component, including,a signal generator to provide a first excitation current to at least one electrode of the first plurality of electrodes,measurement circuitry to measure currents or voltages resulting from the first excitation current traversing fluid in the annulus that is proximate the first fluid sensing component, anda data processor configured to determine impedances corresponding to the measured currents or voltages.
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Abstract
An apparatus and method may operate to mount one or more communication assemblies relative to the exterior of a casing being placed in a borehole. Two communication assemblies can be placed in longitudinally spaced relation to one another along the casing, wherein each communication assembly is configured to obtain excitation responses from electrodes of a fluid sensing component, where the excitation responses vary based on properties of fluids in one or more regions of the annulus surrounding the casing. Additional apparatus, systems, and methods are disclosed.
191 Citations
21 Claims
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1. An assembly, comprising:
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a body member forming a portion of a casing string disposed within a borehole defined by formation sidewalls to define an annulus between the casing string and the formation sidewalls; a first fluid sensing component supported by the body member, the first fluid sensing component including a first plurality of electrodes attached over an outer surface of the casing string and arranged as one or more pairs of electrodes between each of which impedance of fluid in the annulus is measured, wherein for each of the one or more pairs of electrodes, one of the electrodes is offset from the other electrode in a direction longitudinally parallel to the casing string; and an electronics assembly operably coupled to the first fluid sensing component, including, a signal generator to provide a first excitation current to at least one electrode of the first plurality of electrodes, measurement circuitry to measure currents or voltages resulting from the first excitation current traversing fluid in the annulus that is proximate the first fluid sensing component, and a data processor configured to determine impedances corresponding to the measured currents or voltages. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, comprising:
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a casing string in a borehole defined by formation sidewalls, wherein an annulus is defined between the casing string and the formation sidewalls; and first and second communication assemblies supported by the casing string and disposed in longitudinally spaced relation to one another along the casing string, wherein each of the first and second communication assemblies comprises, a frequency generator, and at least one fluid sensing component attached over an outer surface of the casing string that includes one or more pairs of electrodes between each of which impedance of fluid in the annulus is measured, wherein the pairs of electrodes are coupled to the frequency generator and positioned on the outer surface of the casing string, and wherein for each of the pairs of electrodes, one of the electrodes is offset from the other electrode in a direction longitudinally parallel to the casing string. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of making measurements in a borehole, comprising:
- associating a sensor assembly with the exterior of a casing string being placed in the borehole, the sensor assembly configured to sense an electrical property of a fluid in an annulus between the casing string and formation walls defining the borehole, the sensor assembly including a plurality of electrodes in spaced relation to one another;
providing an oscillating excitation signal to a first electrode of the plurality of electrodes;
receiving a first signal at a second electrode of the plurality of electrodes in response to the oscillating excitation signal;determining the electrical property of the fluid in response to the received signal, wherein the electrical property of the fluid is a frequency-dependent dielectric property; and generating a display to display the property of the fluid as a function of frequencies of a series of the oscillating excitation signals. - View Dependent Claims (16, 17, 18, 19, 20, 21)
- associating a sensor assembly with the exterior of a casing string being placed in the borehole, the sensor assembly configured to sense an electrical property of a fluid in an annulus between the casing string and formation walls defining the borehole, the sensor assembly including a plurality of electrodes in spaced relation to one another;
Specification