US3792428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for controlling the downhole acoustic transmitter of a logging-while-drilling system
Assignee: Mobil Oil AS
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Filing: 1972-07-18
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Granted: 1974-02-12
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Expires: 1992-07-18
Abstract
Abstract A logging-while-drilling system utilizes the flow of drilling fluid within a borehole as the transmission medium for telemetering downhole logging measurements to the earth''s surface. The hydraulic power within the drilling fluid is converted to suitable power for driving a downhole acoustic transmitter which produces an acoustic wave within the drilling fluid which is modulated with the information describing the downhole logging conditions. The power available for driving the transmitter is applied to the transmitter when it exceeds the minimum starting power requirement of the transmitter and is continuously applied to the transmitter so long as it does not, after starting the transmitter, drop below the minimum operating power requirement of the transmitter.
Inventors
- 👤 J Harrell
- 👤 J Sexton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:25
CPC Classifications
E; E21; E21B; E21B47/00; E21B47/12; E21B47/14; E21B47/18; E21B47/20
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
291 words
A logging-while-drilling tool comprising: a. an elongated housing adapted for insertion into a borehole, and through which drilling fluid is circulated during drilling operation, b. a rotary-driven member responsive to the hydraulic power in said drilling fluid for generating mechanical power, c. means for converting said mechanical power to electrical power, said electrical power being of alternating current with a frequency directly proportional to the speed of said rotary driven member, d. an acoustic transmitter, driven by said electrical power, said acoustic transmitter periodically interrupting the flow of said drilling fluid through said housing so as to produce a continuous acoustic wave in the drilling fluid, e. means for modulating said acoustic wave in response to a measured downhole condition, the modulated acoustic wave passing upward through the drilling fluid to the surface of the earth where it is demodulated to provide a readout of the measured condition, f. means for converting the frequency of the alternating current of said electrical power to an analog signal of amplitude proportional to the frequency of said alternating current, such analog signal thereby representing the speed of said rotarydriven member, and g. means responsive to said analog signal for providing a control signal of a first state when said analog signal initially exceeds a first voltage level representing the speed of said rotary-driven member required for the generation of the required starting power for said acoustic transmitter and of a second state when said analog signal, after initially exceeding said first voltage level, drops below a second voltage level representing the speed of said rotary-driven member required for the generation of the required operating power for mAintaining continuous operation of said acoustic transmitter, said second voltage level being lower than said first voltage level.
Claim 2
Dependent Claim
291 words
A logging-while-drilling tool comprising: a. an elongated housing adapted for insertion into a borehole, and through which drilling fluid is circulated during drilling operation, b. a rotary-driven member responsive to the hydraulic power in said drilling fluid for generating mechanical power, c. means for converting said mechanical power to electrical power, said electrical power being of alternating current with a frequency directly proportional to the speed of said rotary driven member, d. an acoustic transmitter, driven by said electrical power, said acoustic transmitter periodically interrupting the flow of said drilling fluid through said housing so as to produce a continuous acoustic wave in the drilling fluid, e. means for modulating said acoustic wave in response to a measured downhole condition, the modulated acoustic wave passing upward through the drilling fluid to the surface of the earth where it is demodulated to provide a readout of the measured condition, f. means for converting the frequency of the alternating current of said electrical power to an analog signal of amplitude proportional to the frequency of said alternating current, such analog signal thereby representing the speed of said rotarydriven member, and g. means responsive to said analog signal for providing a control signal of a first state when said analog signal initially exceeds a first voltage level representing the speed of said rotary-driven member required for the generation of the required starting power for said acoustic transmitter and of a second state when said analog signal, after initially exceeding said first voltage level, drops below a second voltage level representing the speed of said rotary-driven member required for the generation of the required operating power for mAintaining continuous operation of said acoustic transmitter, said second voltage level being lower than said first voltage level.
Claim 3
Dependent Claim
86 words
The tool of claim 1 wherein said means for converting the frequency of the alternating current of said electrical power to an analog signal comprises: a. means responsive to said alternating current for generating a digital signal of fixed amplitude and pulse width, the period of said digital signal being the same as the period of the frequency of said alternating current, and b. means for converting said digital signal to an analog signal whose amplitude varies in accordance with the period of said digital signal.
Claim 4
Dependent Claim
166 words
The tool of claim 1 wherein said means for providing said control signal comprises: a. a detector with input supplied by said analog signal, said detector providing a digital output of a first logic level when the amplitude of said analog signal has initially exceeded said first voltage level and has not thereafter dropped below said second voltage level and of a second logic level when the amplitude of said analog signal has not initially exceeded said first voltage level or has, after exceeding said first voltage level, thereafter dropped below said second voltage level, b. a switch coupled to said detector which is turned ON when the digital output of said detector is at said first logic level and is turned OFF when said digital output is at said second logic level, and c. means operable in response to the setting of said switch for providing said control signal, said control signal enabling the acoustic transmitter during the period when said switch is turned ON.
Claim 5
Dependent Claim
92 words
The logging-while-drilling tool of claim 1 wherein said detector comprises: a. an amplifier to which said analog signal is applied, and b. a gate having its input connected to the output of said amplifier and having its output connected through a feedback path to the input of said amplifier, whereby said gate is set to said first logic level when said analog signal exceeds said first voltage level and is maintained at said first logic level by means of said feedback path until said analog signal drops below said second voltage level.
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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) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |