A method comprises conveying a downhole tool in a production tubing within a casing that is around a wall of a wellbore formed in a subsurface formation, wherein cement is placed in an annulus defined between the casing and the wall of the wellbore. The downhole tool includes at least one unipole receiver and at least one of a unipole and a monopole transmitter. The transmitter and receiver are mounted on a rotatable portion of the downhole tool. The method includes performing the following operations at at least two azimuthal positions, emitting an acoustic transmission outward toward the cement and detecting an acoustic response that is in response to the acoustic transmission propagating through the production tubing and the casing and into the cement. The acoustic response includes casing extensional waves, casing non-extensional waves, and tubing waves. The method includes evaluating the cement based on the casing extensional waves.

The present invention pertains to the fields of geology and geophysics, is designed for use for onshore seismic acquisition. The method involves distributing and arranging the elements used in the acquisition of two-dimensional seismic data from dynamite sources, enabling imaging quality to be improved. The use of sources of dynamite with single charges and variable weight at each shot point results in the generation of seismic waves with variable energy that provide reflections with complementary frequency and amplitudes content for use in the geophysical imaging of geological features. The stacking of this incremental content generated by charges of variable weights results in a significant improvement in the resolution of the processed seismic data on both the continuity of stratigraphic reflectors and existing geological framework.

System for building a geological model of oil or other mineral deposit. The system determines functionals represented by the sum of coefficients of correlation for a set of well log curves. A technical result is the improvement of the accuracy of evaluating parameters that are used to build geological model of the location of oil or other deposits. The system makes it possible, given set of markers, chosen as initial solution and to calculate their depths at each well to ensure the best total correlation. For any marker in the set, functional is determined, represented by the sum of correlation coefficients for the set of well log methods for pairs of wells located within specified distance from one another. Partial derivatives are evaluated for this functional, and the vector thus obtained is smoothed and used to search for a larger value of the functional within certain segment along this vector.

Computer-implemented method for determining optimal sampling grid during seismic data reconstruction includes: a) constructing an optimization model, via a computing processor, given by min.sub.uSu.sub.1s.t. Rub.sub.2 wherein S is a discrete transform matrix, b is seismic data on an observed grid, u is seismic data on a reconstruction grid, and matrix R is a sampling operator; b) defining mutual coherence as $\sqrt{\frac{C}{S}\frac{m}{{\left(\log n\right)}^6}},$
wherein C is a constant, S is a cardinality of Su, m is proportional to number of seismic traces on the observed grid, and n is proportional to number of seismic traces on the reconstruction grid; c) deriving a mutual coherence proxy, wherein the mutual coherence proxy is a proxy for mutual coherence when S is over-complete and wherein the mutual coherence proxy is exactly the mutual coherence when S is a Fourier transform; and d) determining a sample grid r.sub.*=arg min.sub.r (r).

Marine vibrators and methods of use are disclosed. A marine vibrator may comprise a containment housing, where the containment housing comprises a marine vibrator internal volume, wherein the marine vibrator internal volume comprises a first gas at a first gas pressure. The marine vibrator may further comprise a sound radiating surface. The marine vibrator may additionally comprise a compliance chamber in contact with the first gas, wherein the compliance chamber comprises a chamber housing and a moveable structure, wherein at least the chamber housing and the moveable structure form a compliance chamber internal volume which holds a second gas at a second gas pressure, wherein the moveable structure is configured to move in response to a change in the first gas pressure, and wherein the compliance chamber is configured to condense the second gas in response to compression of the marine vibrator internal volume by the moveable structure.

In at least one embodiment, a well inspection method and system is disclosed. The method includes transmitting an acoustic signal from a well inspection tool into a casing structure, receiving return signals from the casing structure to the well inspection tool, performing, using at least one processor associated with the well inspection tool, a Fast Fourier Transform (FFT) on a plurality of frequencies of the return signals to generate spectrogram data, determining entropy spectra from the spectrogram data, and determining casing loadings associated with the casing structure based at least in part on the entropy spectra.

The present disclosure provides a physics-based and data-driven integrated method for rock burst hazard assessment, including the following steps: determining an initial stress concentration coefficient by conducting grid discretization on an assessment region, and assigning a value to each of grid nodes using a Weibull distribution function; obtaining a stress concentration coefficient value of each grid node under physics-based models; introducing seismic wave CT detection data to obtain stress concentration coefficient distribution in the assessment region under the integration of a seismic wave CT detection and its derived characterization stress model; introducing microseismic data to obtain stress concentration coefficient distribution in the assessment region under the integration of a microseismic damage reconstruction stress model; and assessing the degree of rock burst hazard according to the size of the stress concentration coefficient value.