Production capability of cased hole perforations in a cased completed well lined with a casing in an under-pressured gas producing reservoir is tested. A sonde of a dipole shear or array sonic (full waveform) acoustic well logging tool is moved in a well bore of the cased completed well in the reservoir across a depth interval of interest, which covers cased hole perforations zones in the reservoir. The well logging sonde has in it an acoustic energy source and acoustic energy receivers. Responses are logged at depth intervals of interest to the transit of Stoneley waves along the casing walls from the acoustic energy source to the acoustic energy receivers. Measures of characteristics (e.g., travel time and attenuation) of the Stoneley wave are obtained. The responses are then processed to indicate production capability of the cased hole perforations.

A method for deblending seismic signals includes entering as input to a computer recorded signals comprising seismic energy from a plurality of actuations of one or more seismic energy sources. A model of deblended seismic data and a blending matrix are initialized. A blending matrix inversion is performed using the initialized model. The inversion includes using a scaled objective function. The inversion is constrained by a thresholding operator. The thresholding operator is arranged to recover coefficients of the model of the deblended seismic data that are substantially nonzero, against a Gaussian white noise background. The thresholded model is projected into data space. Performing the blending matrix inversion is repeated if a data residual exceeds a selected threshold and the inversion is terminated if the data residual is below the selected threshold. At least one of storing and displaying an output of the blending matrix inversion is performed when the blending matrix inversion is terminated.

Waves from cement bond logging with a sonic logging-while-drilling tool (LWD-CBL) are often contaminated with tool waves and may yield biased CBL amplitudes. The disclosed LWD-CBL wave processing corrects the first echo amplitudes of LWD-CBL before calculating the BI. The LWD-CBL wave processing calculates a tool wave amplitude and a phase angle difference as the difference of the phases between the tool waves and casing waves. The tool waves are then used to correct the LWD-CBL casing wave amplitude and remove errors introduced from tool waves. In conjunction with the sets of operations described, the LWD-CBL wave processing also include array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool wave.

A sonic logging method is provided that transmits acoustic signals using a high order acoustic source and processes waveform data to identify a set of arrival events and time picks by automatic and/or manual methods. Ray tracing inversion is carried out for each arrival event over a number of possible raypath types that include at least one polarized shear raypath type to determine two-dimensional reflector positions and predicted inclination angles of the arrival event for the possible raypath types. One or more three-dimensional slowness-time coherence representations are generated for the arrival event and raypath type(s) and evaluated to determine azimuth, orientation and raypath type of a corresponding reflector. The method outputs a three-dimensional position and orientation for at least one reflector. The information derived from the method can be conveyed in various displays and plots and structured formats for reservoir understanding and also output for use in reservoir analysis and other applications.

Aspects provide for methods that successfully evaluates multiple compressional and shear arrival events received by a sonic logging tool to evaluate the presence of structures, such as shoulder beds, in downhole environments. In particular, the methods described herein enable automated determination of properties of laminated reservoir formations by, for example, enabling the automated determination of arrival times and slownesses of multiple compressional and shear arrival events received by a sonic logging tool.

Computing device, computer instructions and method for processing input seismic data d. The method includes receiving the input seismic data d recorded in a first domain by seismic receivers that are towed in water, the input seismic data d including pressure data and/or and particle motion data; generating a model p in a second domain to describe the input data d; processing the model p to generate an output particle motion dataset; and generating an image of the surveyed subsurface based on the output particle motion dataset.

Apparatus, methods, and systems for determining body wave slowness values for a target formation zone. A method includes selecting a target axial resolution based on the size of a receiver array, obtaining a plurality of waveform data sets corresponding to a target formation zone and each acquired at a different shot position, reconstructing the plurality of waveform data sets to generate a plurality of subarray data sets corresponding to the target formation zone, determining a slowness value for each subarray data set and determining a slowness versus offset value for each subarray data set. The method may also include generating a borehole model having at least one alteration formation zone and a virgin formation zone and generating a slowness versus offset model based at least in part on the borehole model. The method may also include determining a radial depth of the alteration formation zone.

A method is provided for identifying and characterizing structures of interest in a formation traversed by a wellbore, which involves obtaining waveform data associated with received acoustic signals as a function of measured depth in the wellbore. A set of arrival events and corresponding time picks is identified by automatic and/or manual methods that analyze the waveform data. A ray tracing inversion is carried out for each arrival event (and corresponding time pick) over a number of possible raypath types to determine i) two-dimensional reflector positions corresponding to the arrival event for the number of possible raypath types and ii) predicted inclination angles of the reflected wavefield for the number of possible raypath types. The waveform data associated with each time pick (and corresponding arrival event) is processed to determine a three-dimensional slowness-time coherence representations of the waveform data for the number of possible raypath types, which is evaluated to determine azimuth position and orientation of a corresponding reflector, and determine the ray path type of the reflected wavefield. The method outputs a three-dimensional position and/or orientation for at least one reflector, wherein the three-dimensional position of the reflector is based on the two-dimensional position of the reflector determined from the ray tracing inversion and the azimuth position of the reflector determined from the three-dimensional slowness-time coherence representation. The information derived from the method can be conveyed in various displays and plots and structured formats for reservoir understanding and also output for use in reservoir analysis and other applications.

A method and system for producing a Quasi-Static Stoneley Slowness log. The method for producing a Quasi-Static Stoneley Slowness log may comprise recording a pressure wave at a receiver; determining a slowness-frequency range with an information handling system from the pressure wave, processing a frequency-domain semblance, extracting a Stoneley Dispersion, minimizing a misfit between theoretical and the Stoneley Dispersion, and identifying Quasi-Static Stoneley slowness from the Stoneley Dispersion. The well measurement system for producing an Quasi-Static Stoneley Slowness log and shear slowness anisotropy may comprise a downhole tool, a vehicle, and an information handling system. Wherein the information handling system may be operable to record a pressure wave at a receiver, determine a slowness-frequency range with an information handling system from the pressure wave, process a frequency-domain semblance, extract a Stoneley Dispersion; minimize a misfit between theoretical and the Stoneley Dispersion; and identify Quasi-Static Stoneley slowness from the Stoneley Dispersion.

A system for attenuating coherent noise from seismic data comprises one or more sensors configured to sense waves generated by a seismic source and a coherent noise attenuation module communicably coupled to the one or more sensors and comprising a processor and memory. The coherent noise attenuation module is operable to receive a plurality of traces of seismic data from the one or more sensors and apply a first transformation to the plurality of traces, identify one or more outlier waveforms in the transformed traces, attenuate the identified outlier waveforms, and apply a second transformation to the plurality of traces that is the inverse of the first transformation.