Method and apparatus for trelemetry while drilling by changing drill string rotation angle or speed
First Claim
1. A method for communicating well platform information from a well platform downhole comprising the steps of:
- selectively rotating a drill string according to said well platform information to be communicated downhole;
simultaneously measuring downhole an angularly dependent geophysical parameter while rotating said drill string, said step of rotating and measuring being effectuated during a predetermined data time interval; and
converting downhole variations of said geophysical parameter, which variations arise during said step of selectively rotating said drill string in accordance with said well platform information, into corresponding information so that said well platform information is transmitted downhole through selective rotation of said drill string.
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Accused Products
Abstract
The cyclic angular dependence of the output of gravitational inclinometers and magnetometers is used to communicate from the well surface to a microprocessor downhole. The microprocessor controls an arbitrary downhole function. Information is communicated to the microprocessor via the inclinometer and magnetometer by selectively rotating the drill string during a data time interval through a predetermined magnitude of angular displacement or angular velocity. Each additional multiple of angular displacement or angular velocity is interpreted as a distinguishable unit of information. A command word is assembled from a sequential plurality of units of information in the microprocessor and a downhole function is executed according to the command word.
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Citations
20 Claims
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1. A method for communicating well platform information from a well platform downhole comprising the steps of:
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selectively rotating a drill string according to said well platform information to be communicated downhole; simultaneously measuring downhole an angularly dependent geophysical parameter while rotating said drill string, said step of rotating and measuring being effectuated during a predetermined data time interval; and converting downhole variations of said geophysical parameter, which variations arise during said step of selectively rotating said drill string in accordance with said well platform information, into corresponding information so that said well platform information is transmitted downhole through selective rotation of said drill string. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. In an apparatus comprising a drill string, platform means for selectively rotating said drill string, and transducer means for generating an analog output signal corresponding to the magnitude of an angularly dependent geophysical parameter downhole, an improvement comprising:
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digitizer means for converting said analog output signal from said transducer means into digital data; and a digital processor means coupled to said digitizer means, said digital processor means for interpreting a measure of periodicity of said geophysical parameter during a predetermined data interval as a distinguishable unit of information, so that communication downhole is simply and reliably effectuated by said platform means for selectively rotating said drill string in accordance with information to be communicated downhole, selective rotation being sensed downhole by said transducer means, converted into digital data by said digitizer means, and being interpreted downhole by said digital processor means as said information. - View Dependent Claims (17, 18, 19)
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20. A method for communicating information downhole on a drill string comprising the steps of:
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measuring a geophysical parameter downhole with at least one sensor; selectively changing the orientation of said sensor downhole during a predetermined data time interval in accordance with said information to be communicated downhole by selective rotation of said drill string; determining the cyclic changes in said geophysical parameter dependent upon orientation of said sensor downhole during said data time interval; and converting said determination of said cyclic nature of said geophysical parameter downhole during said data time interval into a distinguishable unit of information in accordance with said step of selectively changing the downhole orientation of said sensor, so that information is reliably communicated downhole.
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Specification