Apparatus, program product, and methods of evaluating rock properties while drilling using downhole acoustic sensors and a downhole broadband transmitting system

An apparatus for identifying rock properties in real-time during drilling, the apparatus comprising:

• a drill string comprising a plurality of drill pipes each have an inner bore;
• a drill bit connected to the downhole end of the drill string;
• a downhole sensor subassembly connected to and between the drill bit and the drill string, the subassembly containing a downhole data interface;
• a plurality of acoustic sensors contained by the downhole sensor assembly and operably coupled to the downhole data interface;
• a borehole telemetry system for carrying data to a surface computer, the borehole telemetry system comprising the downhole data interface, a communication medium operably coupled to the downhole data interface, and a surface data interface operably coupled to the communication medium, the communication medium comprising a broadband conductor positioned in the inner bore of the plurality of drill pipes and having a bandwidth sufficient to provide substantially lossless transmission of streaming raw acoustic sensor data from the downhole sensor interface to the surface data interface;
• a top drive system for rotating the drill string, the top drive system including rotating and stationary portions, the surface data interface connected to a stationary portion of the top drive system;
• a data acquisition unit positioned to sample acoustic data received from the acoustic sensors and converting data therefrom into digital format;
• and
• the surface computer operably coupled to the downhole data interface through the surface data interface and the communication medium, the computer including a processor, memory in communication with the processor, and a petrophysical properties analyzing program, the computer configured to perform the following operations:
• sending sampling commands to the data acquisition unit,
• receiving digitized raw acoustic sensor data from the data acquisition unit, 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, and
• performing one or more of the following processing operations:
• deriving a plurality of acoustic characteristics from the raw acoustic sensor data, the plurality of acoustic characteristics including mean frequency and normalized deviation of frequency, 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 drilling.

A non-transitory computer readable medium having processor readable petrophysical properties analyzing program code embodied on the computer readable medium, the processor readable program code for programming one or more processors to perform operations for analyzing properties of rock in a formation in real-time during drilling, the processor readable program code comprising a set of instructions that when executed by the one or more processors, cause the one or more processors to perform the operations 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 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, the downhole data interface operably coupled to a plurality of acoustic sensors carried by a downhole sensor assembly,
• receiving digitized raw acoustic sensor data from the surface data acquisition unit;
• transforming the raw acoustic sensor data into the frequency domain,
• filtering the transformed data, and
• performing one or more of the following processing operations:
• deriving a plurality of acoustic characteristics from the filtered data, the plurality of acoustic characteristics including mean frequency and, normalized deviation of frequency, and
• 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.

A non-transitory computer readable medium having processor readable petrophysical properties analyzing program code embodied on the computer readable medium, the processor readable program code for programming one or more processors to perform operations for analyzing properties of rock in a formation in real-time during drilling, the processor readable program code comprising a set of instructions that when executed by the one or more processors, cause the one or more processors to perform the operations of:

• receiving 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 one or more of the following processing operations:
• deriving a plurality of acoustic characteristics from the raw acoustic sensor data, the plurality of acoustic characteristics including mean frequency and normalized deviation of frequency, 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 drilling.