Methods of evaluating rock properties while drilling using downhole acoustic sensors and telemetry system
First Claim
1. A method of determining properties of rock in a formation in real-time during drilling, the method comprising the steps of:
- receiving raw acoustic sensor data from one or more acoustic sensors by a downhole processor assembly, the one or more acoustic sensors carried by a downhole sensor subassembly positioned adjacent a drill bit and between a drill string and the drill bit, the downhole processor assembly positioned in close proximity to the one or more acoustic sensors and operably coupled thereto, the raw acoustic sensor data representing an acoustic signal generated real-time as a result of rotational contact of a drill bit with rock during drilling; and
processing the raw acoustic sensor data by the downhole processor assembly, the processing including deriving a plurality of acoustic characteristics associated with the rock from the raw acoustic sensor data, the plurality of acoustics characteristics including mean frequency and normalized deviation of frequency;
transmitting the plurality of acoustic characteristics to a surface computer over a borehole telemetry system, wherein the surface computer is configured to output a plot of at least one of the plurality of acoustic characteristics versus depth;
performing one or more of the following processing steps at the surface computer;
identifying lithology type of rock being encountered by the drill bit utilizing one or more of the following sets of acoustic characteristics of the plurality of acoustic characteristics;
the mean frequency and the normalized deviation of frequency, the mean frequency and mean amplitude, the mean frequency, the mean amplitude, the normalized deviation of frequency, normalized deviation of amplitude, and apparent power, andderiving petrophysical properties of rock being encountered by the drill bit utilizing a petrophysical properties evaluation algorithm employable to evaluate one or more petrophysical properties of rock undergoing drilling utilizing one or more of the plurality of acoustic characteristics.
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Abstract
Methods of identifying rock properties in real-time during drilling, are provided. An example of method includes connecting a downhole sensor subassembly between a drill bit and a drill string, operably coupling acoustic sensors to a downhole processor, operably coupling a borehole telemetry system, downhole and surface data transmitting interfaces, and a surface computer to the downhole data transmitting interface. The method also includes receiving raw acoustic sensor data resulting from rotational contact of the drill bit with rock by the downhole processor, transforming the raw acoustic sensor data into the frequency domain, filtering the transformed data, and deriving acoustic characteristics from the filtered data. The method also includes the surface computer receiving the acoustic characteristics and deriving petrophysical properties from the acoustic characteristics directly or by utilizing a petrophysical properties evaluation algorithm.
117 Citations
23 Claims
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1. A method of determining properties of rock in a formation in real-time during drilling, the method comprising the steps of:
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receiving raw acoustic sensor data from one or more acoustic sensors by a downhole processor assembly, the one or more acoustic sensors carried by a downhole sensor subassembly positioned adjacent a drill bit and between a drill string and the drill bit, the downhole processor assembly positioned in close proximity to the one or more acoustic sensors and operably coupled thereto, the raw acoustic sensor data representing an acoustic signal generated real-time as a result of rotational contact of a drill bit with rock during drilling; and processing the raw acoustic sensor data by the downhole processor assembly, the processing including deriving a plurality of acoustic characteristics associated with the rock from the raw acoustic sensor data, the plurality of acoustics characteristics including mean frequency and normalized deviation of frequency; transmitting the plurality of acoustic characteristics to a surface computer over a borehole telemetry system, wherein the surface computer is configured to output a plot of at least one of the plurality of acoustic characteristics versus depth; performing one or more of the following processing steps at the surface computer; identifying lithology type of rock being encountered by the drill bit utilizing one or more of the following sets of acoustic characteristics of the plurality of acoustic characteristics;
the mean frequency and the normalized deviation of frequency, the mean frequency and mean amplitude, the mean frequency, the mean amplitude, the normalized deviation of frequency, normalized deviation of amplitude, and apparent power, andderiving petrophysical properties of rock being encountered by the drill bit utilizing a petrophysical properties evaluation algorithm employable to evaluate one or more petrophysical properties of rock undergoing drilling utilizing one or more of the plurality of acoustic characteristics. - View Dependent Claims (2, 3)
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4. A method of determining properties of rock in a formation in real-time during drilling, the method comprising the steps of:
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receiving, over a borehole telemetry system, acoustic characteristics data from a downhole processor assembly by a surface computer, the acoustic characteristics data providing one or more acoustic characteristics derived from acoustic signals, at the downhole processor, provided by one or more acoustic sensors positioned adjacent to a drill bit and generated in real-time as a result of rotational contact of the drill bit with rock during drilling, wherein the one or more acoustic characteristics comprise a plurality of acoustic characteristics including mean frequency and normalized deviation of frequency; outputting a plot, at the surface computer, of at least one of the plurality of acoustic characteristics versus depth; and performing one or more of the following processing steps, at the surface computer, using the acoustic characteristics data; identifying the lithology type of rock being encountered by the drill bit utilizing the mean frequency and the normalized deviation of frequency evaluated from the acoustic signal, and deriving petrophysical properties of rock being encountered by the drill bit utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling utilizing the one or more acoustic characteristics. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of analyzing properties of rock in a formation in real-time during drilling, the method comprising the steps of:
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providing a downhole sensor subassembly, a downhole processor assembly, a downhole data transmitting interface, a surface data transmitting interface, a borehole telemetry system, and a surface computer; connecting the downhole sensor subassembly adjacent to a drill bit for drilling rock and between a drill string and the drill bit, the downhole sensor subassembly carrying one or more acoustic sensors positioned to detect drill sounds during drilling operations and the downhole processor assembly; operably coupling the downhole processor assembly to at least one of the one or more acoustic sensors to receive and process real-time raw acoustic sensor data generated as a result of rotational contact of the drill bit with rocks during operational drilling; operably coupling the downhole processor assembly to the borehole telemetry system via the downhole data transmitting interface to receive and process acoustic characteristics data generated by the downhole processor assembly; transmitting the acoustic characteristics from the downhole processor assembly to the surface computer via the borehole telemetry system; receiving raw acoustic sensor data from the one or more acoustic sensors by the downhole processor assembly, the raw acoustic sensor data representing an acoustic signal generated real-time as a result of rotational contact of the drill bit with rock during drilling; processing the raw acoustic sensor data by the downhole processor assembly, the step of processing including deriving a plurality of acoustic characteristics from the raw acoustic sensor data, the plurality of acoustics characteristics including mean frequency and normalized deviation of frequency; receiving at the surface computer, over the borehole telemetry system, acoustic characteristics data from the downhole processor assembly, the acoustic characteristics data providing the plurality of acoustic characteristics; and performing one or more of the following processing steps at the surface computer; identifying lithology type of rock being encountered by the drill bit utilizing the mean frequency and the normalized deviation of frequency, and deriving petrophysical properties of rock being encountered by the drill bit utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling utilizing one or more of the plurality of acoustic characteristics. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification