Methods and systems for identifying a pay zone in a subterranean formation can include: logging a well extending into the subterranean formation including measuring bulk density, compressional wave travel time and shear wave travel time at different depths in the subterranean formation; calculating elastic attributes including acoustic impedance and compressional velocity-shear velocity ratio at different depths in the subterranean formation; and displaying and analyzing the calculated elastic attributes to identify the low resistivity pay zones.

A method is claimed for automatically transforming sonic well logs from a depth domain to a seismic two-way travel-time domain. The method includes obtaining a training well with a measured sonic well log in the depth domain and a borehole seismic dataset in the depth domain and obtaining an application well with only a measured sonic well log in the depth domain. The method further includes training a network to predict a transformed sonic well log for the training well based, at least in part, on the measured sonic well log and the borehole seismic dataset in the training well, and predicting with the network, the transformed sonic well log in the application well.

A method and system for logging. The method may include disposing an acoustic logging tool into a wellbore, insonifing a pipe string within the wellbore with the acoustic logging tool, recording a plurality of flexural waves with the acoustic logging tool as one or more traces, and identifying a condition of a material behind the pipe string using the plurality of flexural waves. The acoustic logging tool may include one or more transmitters for insonifing a pipe string within a wellbore and one or more receivers configured to record a plurality of flexural waves. Additionally an information handling system may be configured to identify a condition of a material behind the pipe string using the plurality of flexural waves.

Methods and systems for determining an interbed multiple attenuated pre-stack seismic dataset are disclosed. The methods include forming a post-stack seismic image composed of post-stack traces from the pre-stack seismic dataset and identifying a first, second, and third post-stack horizon on each of the post-stack traces. The methods further include for each pre-stack trace, generating a first, second, and third multiple-generator trace based on the first, second and third post-stack horizon and determining a correlation trace based, at least in part, on a correlation between the first multiple-generator trace and the second multiple-generator trace. The methods still further include predicting an interbed multiple trace by convolving the correlation trace and the third multiple-generator trace, determining an interbed multiple attenuated trace by subtracting the interbed multiple trace from a corresponding pre-stack seismic trace, and determining the interbed multiple attenuated pre-stack seismic dataset by combining the interbed multiple attenuated traces.

In seismic imaging, accurate velocity functions (velocity model) defining seismic velocity as a function of depth in the earth are required. The velocity model is obtained as a result of seismic surveying. Delayed travel times in near surface refraction seismic surveys, an effect known as shingling, can result from an anomalous condition, seismic velocity decreasing with depth. Inclusion of such delayed travel times in a tomographic process for seismic imaging would otherwise cause large errors in determination of a seismic velocity model for seismic imaging of subsurface features. At locations (source-receiver offset) in the survey where the shingling occurs, the velocity inversions are identified. The undesirable effects the delayed travel times caused by the velocity inversions are removed from the survey dataset.

The disclosure relates to a method and system for downhole processing of data, such as images, including using a set of downhole sensors to measure parameters relative to the borehole at a plurality of depths and azimuths and detecting predetermined features of the borehole, using a downhole processor, with a trained machine-learning model and extracting characterization data, characterizing the shape and position of the predetermined features that are transmitted to the surface. It also provides a method and system for providing an image of a geological formation at the surface including transmitting a first dataset to the surface that will be used for reconstructing an image at the surface, downhole processing of a second dataset to detect predetermined features and extract characterization data that are transmitted at the surface and displaying a combined image comprising the predetermined features overlaid on the first image.

A method for weathered layer correction of seismic data includes identifying arrival times in the seismic data corresponding to a weathered layer velocity gradient. A velocity model of the weathered layer is generated using the arrival times. The seismic data are time adjusted using the velocity model.

Methods and apparatus are described for using ambient acoustic energy as a passive source in marine seismic surveys. An example embodiment includes (a) accessing signals that were recorded by sensors in the presence of acoustic energy that was emitted by a passive source during a marine seismic survey; (b) identifying a point to represent a location from which the acoustic energy was emitted; (c) isolating, from the recorded signals, a direct wavefield arriving at the sensors from a direction of the identified point; and (d) generating an estimated passive source wavefield at the identified point by backpropagating the isolated direct wavefield to the identified point. The estimated passive source wavefield may be used, together with signals recorded by the sensors, to generate an image of a subsurface earth volume without the use of active seismic sources.

A DAS VSP technique is used to determine the induced fracture height and fracture density of an induced fracture region. The DAS VSP technique obtains pre-hydraulic fracturing DAS VSP survey time-lapse data to establish a baseline reference for the direct acoustic wave travel time. The DAS VSP technique obtains one or more time-lapse data corresponding to the subsequent monitor surveys conducted after each hydraulic fracturing stage along the well. Forward modeling is used to determine a theoretical acoustic wave travel time difference. The forward modeling uses seismic anisotropy to describe the behavior of seismic waves traveling through the induced fracture regions. An inversion scheme is then used to invert for the induced fracture height and the fracture density using the forward modeling. The two extracted induced fracture characteristics may then be used to determine optimal hydraulic fracturing parameters.

Methods and systems including computer programs encoded on a computer storage medium, for utilizing equivalent linear velocity for first arrival picking of seismic refraction. In one aspect, a method includes receiving data for the shot gather record, generating a diving wave equation curve for a particular parameter pair of multiple parameter pairs, and integrating the shot gather record data corresponding to the diving wave equation curve over a selected range of offsets of the shot gather to generate an equivalent linear velocity value for the particular parameter pair and the shot gather record data, selecting, from the equivalent linear velocity values for the plurality of parameter pairs, a greatest equivalent linear velocity value of the equivalent linear velocity values, the greatest equivalent linear velocity value corresponding to a first-arrival parameter pair, and determining, using the first-arrival parameter pair, a set of first-arrival onsets for the selected sub-range of offsets.