Systems and methods for performing focused blind deconvolution of signals received by a plurality of sensors are disclosed. In some embodiments, this may include determining a cross-correlation of first and second signals, obtaining a cross-correlation of a first response function and a second response function based on the cross-correlation of the first and second signals and subject to a first constraint that the first and second response functions are maximally white, and obtaining the first and second response functions based on the cross-correlation of the first and second response functions and subject to a second constraint that the first and second response functions are maximally front-loaded.

A method includes drilling a wellbore into a subsurface using a drill bit and, for each of a plurality of depths of the drill bit in the wellbore, detecting, at each of a plurality of receiver stations located along a fiber optic cable disposed behind a casing string within the wellbore, a seismic signal created by the drill bit drilling the wellbore, sending an optical signal generated by the detection of the seismic signal from each of the plurality of receiver stations to an interrogator, sorting, using a computer processor, the optical signals by receiver station, and determining, using the computer processor, a seismic velocity using first breaks picked from the sorted optical signals.

Acoustic imaging waveforms are measured utilizing a downhole acoustic tool within a wellbore, and then aligned relative to a main echo of each waveform. The aligned waveforms are then subjected to a first low-pass filter. Residuals are extracted by determining differences between the aligned waveforms and the filtered waveforms. The residuals are aligned to corresponding acoustic firing pulses of the downhole acoustic tool. The aligned residuals are subjected to a second low-pass filter. The measured waveforms are aligned to the corresponding acoustic firing pulses. Noise associated with the downhole acoustic tool is removed from the pulse-aligned, measured waveforms utilizing the filtered residuals.

Drilling systems and related methods are disclosed. A drilling systems may include a tool configured to be positioned at an end of a drill string adjacent a drill bit, and the tool may be configured to detect localized seismo-electromagnetic conversion from one or more predetermined positions within a medium ahead of the drill bit. The tool may include two or more pressure sources configured to generate focused acoustic and/or elastic energy at the one or more predetermined positions to generate the localized seismo-electric conversion.

A system includes at least one processing unit and a bottomhole assembly (BHA) that includes or communicates with the at least one processing unit. The BHA includes at least one drilling component and at least one acoustic transducer to convert drilling noise into one or more electrical signals. The at least one processing unit analyzes the one or more electrical signals or related data to categorize different components of the drilling noise as rock contact noise and mechanical noise. The at least one processing unit derives a data log, a plan, or a control signal based on the categorized drilling noise components.

A method for determining properties of rock formations using drill string vibration measurements includes entering into a processor signals corresponding to vibrations detected along a rotating part of a drill string while drilling a borehole. The vibration signals are transformed into transformed signals representing elastic response of the drill string, the rock formations and borehole fluid to a filtered impulse originating at a known location along the drill string. Properties of the rock formations are calculated using the transformed signals.

A vibration while drilling acquisition and signal processing system include a sensor assembly affixable to a drill string in a drilling unit and a sensor for detecting vibrations in the drill string. A first processor is in signal communication with the sensor and is programmed to digitally sample signals from the sensor. A transmitter in signal communication with the first processor communicates the digitized signals to a device disposed apart from the drill string. The first processor is programmed to operate the signal. An electric power source to provides power to the sensor, the first processor and transmitter. Either or both the first processor and a second processor associated with the device is programmed to calculate properties of rock formations using only detected vibration signals from the drill string.

A method for determining properties of rock formations using drill string vibration measurements includes entering into a processor signals corresponding to vibrations detected along a rotating part of a drill string while drilling a borehole. The vibration signals are transformed into transformed signals representing elastic response of the drill string, the rock formations and borehole fluid to a filtered impulse originating at a known location along the drill string. Properties of the rock formations are calculated using the transformed signals.

Extracting a core sample from within a wellbore is optimized based on information extracted from acoustic signals that are generated downhole. The acoustic signals provide an indication of the formation being cored, which is used to obtain or adjust designated coring operating parameters for accomplishing an efficient and effective coring procedure. Coring operating parameters that are adjusted include weight on bit and bit rotational speed. Optimizing coring operating parameters reduces wear on the bit and produces samples with less fractures. Generating acoustic signals is done by the operation of coring itself, or contacting the formation with a coring bit. Contacting includes impacting the coring bit radially against the wellbore's sidewall, or moving the bit laterally after coring operations have initiated.

Apparatus (10) and methods for combining time reversal and elastic nonlinearity of formation materials for qualtitatively probing for over-pressured regions down hole in advance of a well drilling bit, to determine the distance to the over-pressured region, and for accurately measuring pore pressure downhole in a formation, are described. Classical and reciprocal time reversal methods may be utilized to achieve these measurements.