Methods of evaluating rock properties while drilling using downhole acoustic sensors and a downhole broadband transmitting system
First Claim
1. A method of analyzing properties of rock in a formation in real-time during drilling, the method comprising the steps of:
- sending sampling commands to a surface data acquisition unit in communication with a downhole data interface through a surface data interface and a communication medium extending between the surface data interface and the downhole data interface, the downhole data interface operably coupled to a plurality of acoustic sensors carried by a downhole sensor assembly;
receiving, by a computer, digitized raw acoustic sensor data from the surface data acquisition unit, the digitized 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;
transforming the digitized raw acoustic sensor data into the frequency domain;
filtering the transformed data; and
performing, by the computer, the following processing steps in real-time during rotational contact of a drill bit with rock during drilling;
deriving a plurality of acoustic characteristics from the filtered data, the plurality of acoustic characteristics including mean frequency and normalized deviation of frequency,comparing the mean frequency and the normalized deviation of frequency for the rock undergoing drilling with mean frequency and normalized deviation of frequency for a plurality of rock samples having different lithologies; and
identifying lithology type of the rock undergoing drilling responsive to the step of comparing;
deriving petrophysical properties from the filtered data utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling;
providing the one or more petrophysical properties of rock undergoing drilling or the lithology type of the rock undergoing drilling to a driller to assist in drilling operations.
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Abstract
Methods of identifying rock properties in real-time during drilling, are provided. An example of such a method includes connecting a downhole sensor subassembly between a drill bit and a drill string, operably coupling acoustic sensors to a downhole data interface, and operably coupling a surface computer to the downhole data interface. The method can also include receiving raw acoustic sensor data generated real-time as a result of rotational contact of the drill bit with rock during drilling, transforming the raw data into the frequency domain, filtering the transformed data, and deriving a plurality of acoustic characteristics from the filtered data. This can be performed by a petrophysical properties analyzing program stored in memory of the computer. The method can also include deriving petrophysical properties from the filtered data utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling.
111 Citations
20 Claims
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1. 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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sending sampling commands to a surface data acquisition unit in communication with a downhole data interface through a surface data interface and a communication medium extending between the surface data interface and the downhole data interface, the downhole data interface operably coupled to a plurality of acoustic sensors carried by a downhole sensor assembly; receiving, by a computer, digitized raw acoustic sensor data from the surface data acquisition unit, the digitized 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; transforming the digitized raw acoustic sensor data into the frequency domain; filtering the transformed data; and performing, by the computer, the following processing steps in real-time during rotational contact of a drill bit with rock during drilling; deriving a plurality of acoustic characteristics from the filtered data, the plurality of acoustic characteristics including mean frequency and normalized deviation of frequency, comparing the mean frequency and the normalized deviation of frequency for the rock undergoing drilling with mean frequency and normalized deviation of frequency for a plurality of rock samples having different lithologies; and identifying lithology type of the rock undergoing drilling responsive to the step of comparing; deriving petrophysical properties from the filtered data utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling; providing the one or more petrophysical properties of rock undergoing drilling or the lithology type of the rock undergoing drilling to a driller to assist in drilling operations. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. 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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receiving, by a computer, raw acoustic sensor data from a surface data acquisition unit in communication with a downhole data interface through a surface data interface and a communication medium extending between the surface data interface and the downhole data interface, the downhole data interface operably coupled to a plurality of acoustic sensors; and performing, by the computer, the following processing steps in real-time during rotational contact of a drill bit with rock during drilling; deriving a plurality of acoustic characteristics from the raw acoustic sensor data, the plurality of acoustic characteristics including mean frequency, normalized deviation of frequency, mean amplitude, normalized deviation of amplitude, and apparent power, and deriving petrophysical properties from the raw acoustic sensor data utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drillings providing the one or more petrophysical properties of rock undergoing drilling to a driller to assist in drilling operations. - View Dependent Claims (12, 13, 14, 15)
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16. 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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receiving, by a computer, raw acoustic sensor data from a surface data acquisition unit in communication with a downhole data interface through a surface data interface and a communication medium extending between the surface data interface and the downhole data interface, the downhole data interface operably coupled to a plurality of acoustic sensors, 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 deriving a plurality of acoustic characteristics from the raw acoustic sensor data in real-time during rotational contact of a drill bit with rock during drilling, the plurality of acoustic characteristics including mean frequency and normalized deviation of frequency; comparing the mean frequency and the normalized deviation of frequency of the rock undergoing drilling with mean frequency and normalized deviation of frequency of a plurality of rock samples having different lithologies, the mean frequency and normalized deviation of frequency being examined together to determine an amount of correlation of the acoustic characteristics associated with the rock undergoing drilling and the acoustic characteristics associated with the rock samples, the step of comparing being performed substantially continuously during drill bit steering; and performing one or more of the following responsive to the step of comparing; identifying lithology type of the rock undergoing drilling, and determining a location of a formation boundary encountered during drilling; and providing the lithology type of the rock undergoing drilling or the location of the formation boundary to a driller to assist in drilling operations. - View Dependent Claims (17, 18)
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19. 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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receiving, by a computer, raw acoustic sensor data from a surface data acquisition unit in communication with a downhole data interface through a surface data interface and a communication medium extending between the surface data interface and the downhole data interface, 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; deriving petrophysical properties from the raw acoustic sensor data in real-time during rotational contact of a drill bit with rock during drilling utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling; collecting petrophysical properties data describing one or more petrophysical properties of rocks for a plurality of formation samples and correspondent acoustic data for a preselected type of drill bit; processing the collected acoustic data to produce filtered Fast Fourier Transform data; determining one or more relationships between features of the filtered Fast Fourier Transform data and correspondent one or more petrophysical properties of rocks describing petrophysical properties of a plurality of formation samples for the preselected type of drill bit; and coding the determined relationships into computer program code defining the bit-specific petrophysical properties evaluation algorithm; and wherein the step of deriving the petrophysical properties includes employing the bit-specific petrophysical properties evaluation algorithm to predict one or more petrophysical properties of the rock undergoing drilling real-time responsive to filtered data associated with raw acoustic sensor data produced in response to the drillings providing the one or more petrophysical properties of rock undergoing drilling to a driller to assist in drilling operations.
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20. A method of analyzing properties of rock in a formation in realtime during drilling, the method comprising the steps of:
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receiving, by a computer, raw acoustic sensor data from a surface data acquisition unit in communication with a downhole data interface through a surface data interface and a communication medium extending between the surface data interface and the downhole data interface, 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; deriving petrophysical properties from the raw acoustic sensor data in real-time during rotational contact of a drill bit with rock during drilling utilizing a petrophysical properties evaluation algorithm employable to predict one or more petrophysical properties of rock undergoing drilling; collecting petrophysical properties data describing one or more petrophysical properties of rocks for a plurality of formation samples and correspondent acoustic data for a plurality of different types of drill bits; processing the collected acoustic data to produce filtered Fast Fourier Transform data; determining bit-type independent features of the filtered Fast Fourier Transform data; determining one or more relationships between the bit-type independent features of the filtered Fast Fourier Transform data and correspondent one or more petrophysical properties of the rocks; and coding the determined relationships into computer program code defining the bit-independent petrophysical properties evaluation algorithm; and wherein the step of deriving the petrophysical properties includes employing the bit-independent petrophysical properties evaluation algorithm to predict one or more petrophysical properties of the rock undergoing drilling real-time responsive to filtered data associated with raw acoustic sensor data produced in response to the drillings providing the one or more petrophysical properties of rock undergoing drilling to a driller to assist in drilling operations.
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Specification