Patent US3701006A successfully refreshed from Google Patents.
US3701006A
Expired / Lapsed
US
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Methods and apparatus for measuring the electrical resistivity of flowing drilling muds
Assignee: Schlumberger Technology Corp
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Filing: 1970-11-05
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Granted: 1972-10-24
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Expires: 1990-11-05
Abstract
Abstract As a representative embodiment of the invention disclosed herein, one or more electrical measuring devices are placed at selected locations in the drilling mud circulating system of a conventional drilling rig for accurately determining the resistivity of the drilling mud flowing past those locations. To obtain these measurements, electrical current is passed between spaced electrodes arranged in an electrically-isolated conduit that is disposed in a stream of the drilling mud. In one embodiment of the invention, new and improved means are provided for measuring all of the current passing between the electrodes regardless of the diverse paths which the current may follow. In an alternative embodiment of the invention, unique means are employed for assuring that all of the current passing between the electrodes will be only along specified paths within the electrically-isolated conduit so that a measurement of the current flowing along only of these specified paths will be sufficient for accurately determining the resistivity of the mud. New and improved thermally-responsive control means are also disclosed for converting the resistivity measurements obtained while practicing the present invention to resistivity measurements at a selected temperature.
Inventors
- 👤 George D Volkel
- 👤 Milton E Cram
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:19
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/06; G01N27/08; E; E21; E21B; E21B49/00; E21B49/005
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
363 words
Apparatus adapted for measuring the electrical resistivity of drilling muds and comprising: an electrically insulated tubular conduit adapted to be immersed in a flow of drilling mud for dividing the flowing mud into a first stream flowing exteriorly of said conduit and a second stream flowing through the interior bore of said conduit and electrically insulated from said first stream; current-supplying means adapted for dividing a constant electrical current of a known total magnitude into one current fraction of an unknown magnitude passing exteriorly of said conduit through said first stream of drilling mud as well as along one portion of said conduit bore through said second stream of drilling mud and into a remaining current fraction of an unknown magnitude passing exclusively along another portion of said conduit bore through said second stream of drilling mud and consisting solely of a single pair of current electrodes spatially disposed in said conduit bore at opposite ends of said other portion thereof, and constant-current source means adapted for supplying an alternating current of said known total magnitude to said current electrodes; first measuring means exclusively responsive to said one current fraction and including a first pair of measuring electrodes spatially disposed in said one portion of said conduit bore to one side of said current electrodes, and first coupling means operatively coupled to said first pair of measuring electrodes for providing a first signal representative of the potential difference between said first measuring electrodes; second measuring means exclusively responsive to said other current fraction and including a second pair of measuring electrodes spatially disposed in said other portion of said conduit bore between said current electrodes, and second coupling means operatively coupled to said second pair of measuring electrodes for providing a second signal representative of the potential difference between said measuring electrodes; and output means operatively coupled to said first and second coupling means and adapted for combining said first and second signals to provide measurements representative solely of the electrical resistivity of said second stream of drilling mud flowing through said conduit bore in response to the flow of said constant electrical current between said constant-current source means and said current electrodes.
Claim 2
Dependent Claim
363 words
Apparatus adapted for measuring the electrical resistivity of drilling muds and comprising: an electrically insulated tubular conduit adapted to be immersed in a flow of drilling mud for dividing the flowing mud into a first stream flowing exteriorly of said conduit and a second stream flowing through the interior bore of said conduit and electrically insulated from said first stream; current-supplying means adapted for dividing a constant electrical current of a known total magnitude into one current fraction of an unknown magnitude passing exteriorly of said conduit through said first stream of drilling mud as well as along one portion of said conduit bore through said second stream of drilling mud and into a remaining current fraction of an unknown magnitude passing exclusively along another portion of said conduit bore through said second stream of drilling mud and consisting solely of a single pair of current electrodes spatially disposed in said conduit bore at opposite ends of said other portion thereof, and constant-current source means adapted for supplying an alternating current of said known total magnitude to said current electrodes; first measuring means exclusively responsive to said one current fraction and including a first pair of measuring electrodes spatially disposed in said one portion of said conduit bore to one side of said current electrodes, and first coupling means operatively coupled to said first pair of measuring electrodes for providing a first signal representative of the potential difference between said first measuring electrodes; second measuring means exclusively responsive to said other current fraction and including a second pair of measuring electrodes spatially disposed in said other portion of said conduit bore between said current electrodes, and second coupling means operatively coupled to said second pair of measuring electrodes for providing a second signal representative of the potential difference between said measuring electrodes; and output means operatively coupled to said first and second coupling means and adapted for combining said first and second signals to provide measurements representative solely of the electrical resistivity of said second stream of drilling mud flowing through said conduit bore in response to the flow of said constant electrical current between said constant-current source means and said current electrodes.
Claim 3
Dependent Claim
18 words
The apparatus of claim 1 wherein said conduit bore is cylindrical at least between all of said electrodes.
Claim 4
Dependent Claim
19 words
The apparatus of claim 1 wherein the output frequency of said constant-current source means is between 60 to 2,000-cycles/second.
Claim 5
Dependent Claim
91 words
The apparatus of claim 1 wherein said output means include: recorder means adapted for recording input signals applied thereto as a function of electrical resistivity, and an amplifier having its output coupled to said recorder means; and wherein said first and second coupling means respectively include first and second transformers operatively coupled between the input of said amplifier and said first and second measuring electrodes for supplying input signals to said amplifier which are representative of the summation of the potential differences respectively developed across said first and second measuring electrodes.
Claim 6
Dependent Claim
63 words
The apparatus of claim 4 wherein the spacing between said second and third electrodes is equal to the spacing between said fourth and fifth electrodes so that the summation of said potential differences will be equal to the product of the total current output of said current-source means and the electrical resistance of a drilling mud flowing between said second and third electrodes.
Claim 7
Dependent Claim
66 words
The apparatus of claim 4 further comprising: a resistive network including thermally-responsive variable resistance means mounted on said conduit and operatively coupled to the input of said amplifier, and fixed resistance means operatively coupled to said amplifier and said thermally responsive resistance means for selectively regulating the gain of said amplifier in linear correspondence with changes in the temperature of a drilling mud passing said conduit.
Claim 8
Dependent Claim
111 words
The apparatus of claim 13 wherein said thermally responsive resistance means are in series with said amplifier input, and said fixed resistance means include a first resistor in series with said thermally responsive means, a second resistor in parallel with said first resistor and said thermally responsive resistance means, and a third resistor coupled to the output and said input of said amplifier, the values of said first, second and third resistors being selected in relation to the characteristics of said thermally responsive resistance means to regulate the gain of said amplifier in accordance with a linear equation converting resistivity at a given temperature to resistivity at a selected constant temperature.
Claim 9
Dependent Claim
307 words
Apparatus adapted for measuring the electrical resistivity of drilling muds and comprising: an electrically-insulated tubular conduit adapted to be immersed in a stream of drilling mud for electrically isolating that portion of the stream flowing through the interior bore of said conduit from the remainder of the stream flowing exteriorly of said conduit; six electrodes spatially disposed along said conduit bore; current-source means operatively coupled across the first and fourth ones of said electrodes and adapted for applying thereto an alternating current of a constant amplitude; recorder means adapted for recording input signals applied thereto as a function of electrical resistivity; an amplifier having its output coupled to said recorder means; first and second coupling means respectively coupled between said second and third electrodes and said fifth and sixth electrodes and the input of said amplifier for supplying input signals to said amplifier which are representative of the summation of the potential differences respectively developed across said second and third electrodes and said fifth and sixth electrodes; and temperature-compensating means for selectively regulating the gain of said amplifier response to changes in the temperature of a drilling mud passing said conduit including a resistive network having thermally-responsive variable resistance means mounted on said conduit and operatively coupled in series with the input of said amplifier, and fixed resistance means including a first resistor in series with said thermally-responsive resistance means, a second resistor in parallel with said first resistor and said thermally responsive resistance means, and a third resistor coupled to the output and said input of said amplifier, the values of said first, second and third resistors being selected in relation to the characTeristics of said thermally responsive resistance means to regulate the gain of said amplifier in accordance with a linear equation converting resistivity at a given temperature to resistivity at a selected constant temperature.
Claim 10
Dependent Claim
307 words
Apparatus adapted for measuring the electrical resistivity of drilling muds and comprising: an electrically-insulated tubular conduit adapted to be immersed in a stream of drilling mud for electrically isolating that portion of the stream flowing through the interior bore of said conduit from the remainder of the stream flowing exteriorly of said conduit; six electrodes spatially disposed along said conduit bore; current-source means operatively coupled across the first and fourth ones of said electrodes and adapted for applying thereto an alternating current of a constant amplitude; recorder means adapted for recording input signals applied thereto as a function of electrical resistivity; an amplifier having its output coupled to said recorder means; first and second coupling means respectively coupled between said second and third electrodes and said fifth and sixth electrodes and the input of said amplifier for supplying input signals to said amplifier which are representative of the summation of the potential differences respectively developed across said second and third electrodes and said fifth and sixth electrodes; and temperature-compensating means for selectively regulating the gain of said amplifier response to changes in the temperature of a drilling mud passing said conduit including a resistive network having thermally-responsive variable resistance means mounted on said conduit and operatively coupled in series with the input of said amplifier, and fixed resistance means including a first resistor in series with said thermally-responsive resistance means, a second resistor in parallel with said first resistor and said thermally responsive resistance means, and a third resistor coupled to the output and said input of said amplifier, the values of said first, second and third resistors being selected in relation to the characTeristics of said thermally responsive resistance means to regulate the gain of said amplifier in accordance with a linear equation converting resistivity at a given temperature to resistivity at a selected constant temperature.
Claim 11
Dependent Claim
336 words
Apparatus adapted for measuring the electrical resistivity of drilling muds and comprising: an electrically-insulated tubular conduit adapted to be immersed in a stream of drilling mud for electrically isolating that portion of the stream flowing through the interior bore of said conduit from the remainder of the stream flowing exteriorly of said conduit; three current-conducting electrodes spatially disposed along said conduit bore; current-source means operatively coupled between the two outwardly disposed ones of said current-conducting electrodes and the intermediate one of said current-conducting electrodes and adapted for applying thereto an alternating current of a constant amplitude; a pair of measuring electrodes spatially disposed along said conduit bore between one of said outwardly-disposed current-conducting electrodes and said intermediate current-conducting electrode; recorder means adapted for recording input signals applied thereto as a function of electrical resistivity; an amplifier having its output coupled to said recorder means; transformer means operatively coupled between the input of said amplifier and said measuring electrodes for supplying input signals to said amplifier which are representative of the potential differences developed across said measuring electrodes in response to the flow of electrical current between said current-source means and said current-conducting electrodes; and temperature-compensating means for selectively regulating the gain of said amplifier in response to changes in the temperature of a drilling mud passing said conduit including a resistive network having thermally responsive variable resistance means mounted on said conduit and operatively coupled in series with the input of said amplifier, and fixed resistance means including a first resistor in series with said thermally responsive resistance means, a second resistor in parallel with said first resistor and said thermally responsive resistance means, and a third resistor coupled to the output of said input of said amplifier, the values of said first, second and third resistors being selected in relation to the characteristics of said thermally responsive resistance means to regulate the gain of said amplifier in accordance with a linear equation converging resistivity at a given temperature to resistivity at a selected constant temperature.
Claim 12
Dependent Claim
336 words
Apparatus adapted for measuring the electrical resistivity of drilling muds and comprising: an electrically-insulated tubular conduit adapted to be immersed in a stream of drilling mud for electrically isolating that portion of the stream flowing through the interior bore of said conduit from the remainder of the stream flowing exteriorly of said conduit; three current-conducting electrodes spatially disposed along said conduit bore; current-source means operatively coupled between the two outwardly disposed ones of said current-conducting electrodes and the intermediate one of said current-conducting electrodes and adapted for applying thereto an alternating current of a constant amplitude; a pair of measuring electrodes spatially disposed along said conduit bore between one of said outwardly-disposed current-conducting electrodes and said intermediate current-conducting electrode; recorder means adapted for recording input signals applied thereto as a function of electrical resistivity; an amplifier having its output coupled to said recorder means; transformer means operatively coupled between the input of said amplifier and said measuring electrodes for supplying input signals to said amplifier which are representative of the potential differences developed across said measuring electrodes in response to the flow of electrical current between said current-source means and said current-conducting electrodes; and temperature-compensating means for selectively regulating the gain of said amplifier in response to changes in the temperature of a drilling mud passing said conduit including a resistive network having thermally responsive variable resistance means mounted on said conduit and operatively coupled in series with the input of said amplifier, and fixed resistance means including a first resistor in series with said thermally responsive resistance means, a second resistor in parallel with said first resistor and said thermally responsive resistance means, and a third resistor coupled to the output of said input of said amplifier, the values of said first, second and third resistors being selected in relation to the characteristics of said thermally responsive resistance means to regulate the gain of said amplifier in accordance with a linear equation converging resistivity at a given temperature to resistivity at a selected constant temperature.
Claim 13
Dependent Claim
18 words
The apparatus of claim 9 wherein said conduit bore is cylindrical at least between said outwardly disposed electrodes.
Claim 14
Dependent Claim
18 words
The apparatus of claim 9 wherein the output frequency of said current-source means is between 60 and 2,000-cycles/second.
Claim 15
Dependent Claim
38 words
The apparatus of claim 9 wherein said intermediate current-conducting electrode is positioned midway between said outwardly disposed current-conducting electrodes so that the current output of said current-source means will be divided equally between said outwardly disposed current-conducting electrodes.
Claim 16
Independent Claim
215 words
A method for measuring the electrical resistivity of a stream of drilling mud comprising the steps of: placing an electrically-insulated tubular conduit into said mud stream for isolating a part thereof within the interior bore of said conduit from the remainder of said mud stream exterior of said conduit; passing a first portion of electrical current directly through a first part of said isolated mud stream between a pair of spaced current electrodes; passing a second portion of electrical current from one of said spaced electrodes in an indirect path looping from one end of said conduit outwardly around the exterior of said conduit and back through a second part of said isolated mud stream between the other end of said conduit and the other one of said spaced electrodes; measuring the potential difference developed across a seLected segment of said first part of said isolated mud stream by the passage of said first current portion; measuring the potential difference developed across a selected segment of said second part of said isolated mud stream by the passage of said second current portion; and adding a function of said measured potential differences, respectively, to obtain a characteristic which is representative of the resistivity of said isolated mud stream flowing through said interior bore of said conduit.
Claim 17
Independent Claim
215 words
A method for measuring the electrical resistivity of a stream of drilling mud comprising the steps of: placing an electrically-insulated tubular conduit into said mud stream for isolating a part thereof within the interior bore of said conduit from the remainder of said mud stream exterior of said conduit; passing a first portion of electrical current directly through a first part of said isolated mud stream between a pair of spaced current electrodes; passing a second portion of electrical current from one of said spaced electrodes in an indirect path looping from one end of said conduit outwardly around the exterior of said conduit and back through a second part of said isolated mud stream between the other end of said conduit and the other one of said spaced electrodes; measuring the potential difference developed across a seLected segment of said first part of said isolated mud stream by the passage of said first current portion; measuring the potential difference developed across a selected segment of said second part of said isolated mud stream by the passage of said second current portion; and adding a function of said measured potential differences, respectively, to obtain a characteristic which is representative of the resistivity of said isolated mud stream flowing through said interior bore of said conduit.
Claim 18
Dependent Claim
16 words
The method of claim 13 wherein said selected segments are distributed longitudinally along said conduit bore.
Claim 19
Dependent Claim
40 words
The method of claim 13 wherein said selected segments are distributed longitudinally along said conduit bore and are of equal lengths so that the summation of said potential differences will be directly proportional to the resistivity of said mud stream.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |