Systems and methods for downhole signal filtering. A method for downhole signal filtering may comprise defining outliers as isolated values; providing thresholds; determining the outliers from a buffer; computing a difference in slowness between adjacent pairs of values; comparing the adjacent pairs of values to other values in a same window; determining if the adjacent pairs of values vary more than the threshold; assigning a 2D flag array a value of 0 if the adjacent pairs of values vary more than the threshold; and computing a 75% percentile distribution for each adjacent pair of values to determine if each adjacent pair of values are the outliers.

Image feature alignment is provided. In some implementations, a computer-readable tangible medium includes instructions that direct a processor to access a reference feature point associated with a high contrast region in a first sub-image that is associated with a first section of a borehole. Instructions are also present that direct the processor to identify several candidate feature points in a second sub-image associated with a second section of the borehole adjacent to the first section of the borehole, with each of the candidate feature points being believed to possibly be associated with the high contrast region. Additional instructions are present that direct the processor to prune the candidate feature points using global solution pruning to arrive at a matching candidate feature point in the second sub-image.

Some systems and methods for determining depths of subterranean formation layer tops while drilling through the subterranean formation include a drill bit, a drill rig, a microphone, a depth sensor, and a processor. While drilling the through the subterranean formation, the processor receives a measured sound from the microphone and a measured drill bit depth from the depth sensor, normalizes the measured sound across all measured drill bit depths, determines frequency information of the normalized sound for each depth of the plurality of depths, determines frequency spectrums of the normalized sound for one or more depths of the plurality of depths, transforms the frequency spectrums into a depth spectrum, and determines the depths of subterranean formation layer tops based on the depth spectrum.

An example mud pulse telemetry method includes positioning an external acoustic or vibration sensor on or near a pump to collect acoustic or vibration data during operation of the pump. The method also includes monitoring a pressure of fluid in a tubular, the fluid conveying a data stream as a series of pressure variations. The method also comprises processing the monitored pressure to demodulate the data stream. The processing uses a pump noise estimate obtained at least in part from analysis of the acoustic or vibration data.

A method and system for real-time prediction of jamming in TBM tunneling. The method includes: (1) obtaining actually measured TSP physical property parameters by applying a TSP method; (2) analyzing value ranges and change trends of the TSP physical property parameters obtained in real time; (3) establishing a TSP physical property parameter sample database of a TBM tunnel; (4) establishing a mapping relationship between TSP physical property parameters and occurrence or not of jamming; (5) establishing a mapping relationship between time sequence values of tunneling parameters and occurrence or not of jamming; and (6) forecasting a TBM jamming risk in real time, and storing reliable data into the TSP physical property parameter sample database. The method and system can effectively obtain a state of surrounding rocks in time, thereby providing real-time forecasting of TBM tunneling jamming, avoiding occurrence of accidents to some extent, and improving the TBM tunneling efficiency.

A method evaluating borehole subsurface geologies can include receiving a total response signal by a sensor array disposed in a borehole, the response signal represents a pressure wave propagating in the borehole. A secondary signal can be extracted from the total response signal and a depth location for at least one secondary source that corresponds to the secondary signal is determined. An estimated reflectivity response for the secondary signal as a function of frequency is determined and the estimated reflectivity response is inverted to determine the secondary source includes at least one of a potential fracture or a potential washout. The at least one of a fracture conductivity or a washout volume for the secondary source is compared to one or more borehole images corresponding to the depth location of the secondary source to determine the potential fracture is an actual fracture or the potential washout is an actual washout.

A technique facilitates use of acoustic measurements to enable geo-steering during a well operation. A steerable well string is provided with acoustic systems used to collect data which is then processed to determine geo-steering inputs. In some applications, the well string may comprise a coiled tubing drilling tool. The coiled tubing drilling tool or other well string tool is combined with an azimuthally distributed pitch-catch micro-sonic sensor system and an azimuthally distributed ultrasonic pulse-echo transducer system. Data from these two systems is provided to a processing system which processes the data to determine, for example, real-time, geo-steering inputs. These inputs may then be used to more effectively steer the coiled tubing drilling tool or other well string tool.

A method can include accessing data associated with a well and one or more offset wells; based on at least a portion of the data, generating a set of distributions via parametric estimation, where the distributions are associated with a well-related activity and time; analyzing individual distributions in the set of distributions with respect to at least a portion of the data to pass or fail each of the individual distributions; and, for one or more passed individual distributions, outputting one of the passed individual distributions for the well.

Systems and methods for monitoring subsea equipment are described herein. In one embodiment, such a system can include a plurality of acoustic sensor arrays that each include at least two acoustic sensors, wherein at least a first acoustic sensor array is mounted on an outer surface of subsea equipment being monitored and at least a second acoustic sensor array is positioned remote from the subsea equipment. The system can also include a digital data processor in communication with the plurality of acoustic sensor arrays, the digital data processor can be configured to process data from selected sensors of the plurality of acoustic sensor arrays to both selectively focus on a portion of the subsea equipment and to determine a point of origin of an acoustic signal. The system can be particularly useful in detecting leaks and other events in subsea drilling equipment.

In some embodiments, a method acquires acoustic data with a receiver. The acoustic data is provided by a down hole tool, comprising the receiver, that can move within a borehole in a geological formation. Quality control workflow charts, representing selected acoustic data related to the down hole tool, the geological formation, and/or the borehole can be displayed, transformation controlled, and analyzed on a monitor. The quality control workflow charts comprise the selected acoustic data and/or transformed versions of signal waveforms of the selected acoustic data.