Methods, systems, and devices for evaluating an earth formation intersected by a borehole using information from standard resolution measurements. Methods include generating an image representative of the formation over an interval of borehole depth, the image having a second resolution greater than the first resolution. Generating the image may be carried out by identifying layers corresponding to lithotype facies within the interval, the layers defined by boundaries having boundary locations along the borehole; and using a unified characterization of the formation within the interval determined from the standard resolution measurements and the boundary locations within the interval to solve for a value for the formation parameter corresponding to each layer consistent with the unified characterization of the interval. The unified characterization may be an average value for the formation parameter within the interval.

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.

Techniques involve obtaining acoustic data (including waves reflected from the casing, the annular fill material, the formation, and/or interfaces between any of the mud, the casing, and the annular fill material) from an acoustic logging tool. Techniques include normalizing the acoustic wave to result in a normalized wave having a comparable spectral shape with a reference wave, and comparing the normalized wave with the reference wave. The reference wave may be generated or modeled or produced from a look-up table or database, and may be estimated based on initial estimates of wellbore parameters. Based on the comparison of the normalized wave with the reference wave, a best-fit reference wave substantially matching the normalized wave may be identified. The best-fit reference wave may correspond with a thickness of the casing, an acoustic impedance of the annular fill material, and an acoustic impedance of mud.

An Earth model of a subsurface is created from acquired seismic data by migrating at least one of the incident wavefields and reflected wavefields to generate angle gathers for the seismic data and identifying for the subsurface an elastic Earth model equation for the incident wavefields and the reflected wavefields in the acquired seismic data. The elastic Earth model is a function of reflection angle between the incident wavefields and reflected wavefields and elastic parameters and is fit to the generated angle gathers through perturbation in the elastic parameters. The generated perturbations are used to create the Earth model of the subsurface.

Methods, systems, and devices for downhole evaluation using a sensor assembly that includes a sensor plate, wherein a surface of the sensor plate forms a portion of a surface of a downhole tool. Methods include bringing the surface of the sensor plate into contact with downhole fluid; generating a guided wave that propagates in the sensor plate by activating the sensor assembly at at least one frequency configured to excite both a symmetric mode and an anti-symmetric mode; making at least one first attenuation measurement of the symmetric mode of the guided wave; making at least one second attenuation measurement of the anti-symmetric mode of the guided wave; and using the at least one first attenuation measurement and the at least one second attenuation measurement to estimate at least one parameter of interest of the fluid. Methods may include submerging the surface of the sensor plate in a downhole fluid.

Mapping is performed of chemostratigraphic signatures of hydrocarbon reservoirs in three dimensions. Up-scaled chemostratigraphic data from well cuttings and well cores are tied with high-resolution elastic wireline data at well locations in the reservoir. The wireline data is used to determine suitable seismic attributes for mapping the desired chemostratigraphic property, and are obtained by performing pre- and/or post-stack inversions. A multi-attribute template, derived from the well data, is developed to characterize the reservoir in terms of its chemostratigraphic properties. The seismic data is then inverted to map the chemostratigraphic signatures of reservoir in three dimensions.

The present disclosure generally relates to a real-time synthetic logging method for optimizing one or more operations in a well. The method generally includes receiving measurements of one or more parameters in real time while performing operations in the well, the measurements being captured without using tools that include active nuclear sources. The method further includes providing the measurements as input to a machine learning algorithm (MLA) that is trained using historical or training well data. The method further includes generating, using the MLA and based on the measurements, a synthetic mechanical property log of the well. The method further includes generating, based on the synthetic mechanical property log, optimized parameters for at least one operation selected from the following list: drilling the well in real-time; steering the well in real-time; and stimulating a reservoir in real-time.

A system for processing seismic data for a geologic formation generated by an array of acoustic transducers responsive to an acoustic source may include a seismic data storage device and a processor. The processor may cooperate with the seismic data storage device to use a volatility measurement model to generate current correlations of data from the array of acoustic transducers based upon a current estimate for at least one of density and velocity of the geologic formation, and compare the current correlations to a threshold. When the current correlations are below the threshold, the processor may update the current estimate for at least one of density and velocity of the geologic formation, and repeat use of the volatility measurement model to generate updated correlations of data from the array of acoustic transducers based upon the updated estimate for at least one of density and velocity of the geologic formation.

A method to measure borehole Stoneley wave slowness and its associated tool-corrected dispersion curve. The method for measuring borehole Stoneley wave slowness may comprise gathering waveforms, conditioning waveforms, identifying slowness constraints, computing a time-slowness mask, computing a coherence map from differential phase time semblance, processing a two-dimensional time-slowness map, determining slownesses from a one-dimensional variable density log, and tracking time pick from a two-dimensional map. The method may further comprise identifying one or more of coherence, power, instantaneous frequency, signal-to-noise ratio, or error bars from the two-dimensional time-slowness map. The method may further computing a spline interpolation locally around the pick from the one-dimensional variable density log to produce a final data product.

Techniques for estimating and visually presenting formation slowness are disclosed herein. The techniques include receiving acoustic signal responses from adjacent formations at a plurality of depths in a borehole environment, mapping a distribution of the acoustic signal responses at each depth according to slowness and a frequency values, determining at least one confidence interval to define a coherence threshold for the distribution of the acoustic signal responses at each depth, generating a variable density log for each depth based on the distribution of acoustic signals responses that satisfy the confidence interval for one or more frequency ranges, determining a formation slowness value for each depth based on the variable density log for the each depth, and presenting a semblance map that includes a slowness axis, a depth axis, the formation slowness value for each depth, and at least a portion of the distribution of acoustic signal responses at each depth.