Implementations described and claimed herein provide systems and methods for isolation detection. In one implementation, an acoustic signal is obtained. The acoustic signal is captured at a set of acoustic receivers deployed in a structure in a subterranean surface. A differential acoustic signal is produced from the acoustic signal captured at the set of acoustic receivers. A symmetry within a portion of the structure is determined based on a value of the differential acoustic signal. At least one isolation region is detected within the structure based on the symmetry.

Implementations described and claimed herein provide systems and methods for isolation detection. In one implementation, an axial acoustic signal is obtained. The axial acoustic signal is captured using an axial sensor deployed in a structure in a subterranean surface. The axial acoustic signal is separated into a first wave region and a second wave region by applying velocity filtering. An axial symmetry of a portion of the structure is determined based on at least one of the first wave region or the second wave region.

A seismic system that includes a seismic source configured to generate a first seismic signal and a second seismic signal in a formation adjacent the seismic source. A first downhole sensing device disposed in a first borehole configured to detect the first seismic signal and the second seismic signal in the formation; and a first surface acquisition system is in communication with the first downhole sensing device. The first surface acquisition system is configured to: determine a first reference transit time based at least in part on detection of the first seismic signal by the first downhole sensing device; a first subsequent transit time based at least in part on detection of the second seismic signal by the first downhole sensing device; and whether a synchronization variation is expected to be present based at least in part on the first reference transit time and the first subsequent transit time.

Processes and systems described herein are directed to performing marine surveys with marine vibrators that emit orthogonal coded pseudo-random sweeps. In one aspect, coded pseudo-random signals are generated based on coded pseudo-random sequences. The coded pseudo-random sequences are used to activate the marine vibrators in a body of water above a subterranean formation. The activated marine vibrators generate orthogonal coded pseudo-random sweeps. A wavefield emitted from the subterranean formation in response to the orthogonal coded pseudo-random sweeps is detected at receivers located in a body of water. Seismic signals generated by the receivers may be cross-correlated with a signature of one of the orthogonal coded pseudo-random sweeps to obtain seismic data with incoherent residual noise.

Implementations described and claimed herein provide systems and methods for isolation detection. In one implementation, a radial acoustic log is obtained. The radial acoustic log is captured using a radial sensor of an acoustic logging tool deployed within a first structure. The first structure disposed within a second structure in a subterranean environment. A radial symmetry is determined using the radial acoustic log. An eccentricity of the first structure relative to the second structure is determined based on the radial symmetry.

An acoustic tool, system, and method for performing down-hole measurements. An encoded pulse sequence is transmitted from an acoustic tool. First reflections are received from the encoded pulse sequences. The first reflections from the encoded pulse sequence are identified from a number of reflections of the encoded pulse sequence. Measurements are performed utilizing the first reflections of the encoded pulse sequence. Other systems and methods are presented.

A method for applying separated wave-field imaging onshore (1) by artificially creating up-going and down-going fields and (2) by using these fields in a migration algorithm. If there are any surface multiples in the data, the resulting image created using the migration algorithm will be distorted by the unknown free-surface reflection coefficient. In fact, the surface multiples may be generated with a complex series of reflection coefficients. The distortions found in the resulting image created using the migration algorithm are then removed.

Methods comprising electronically receiving information of a reflection of a known first sound pulse, electronically receiving information of a reflection of a known second sound pulse, determining, by a processor, a change in a first property between a known first sound pulse and a reflection of the known first sound pulse, determining, by the processor, a change in a second property between a known second sound pulse and a reflection of the known second sound pulse, comparing, by the processor, the change in the first property of the first known sound pulse with the change in the second property of the second known sound pulse, and determining, by the processor, a condition of a well in response to the comparison of the change of the first property with the change of the second property are disclosed. Systems for determining a condition of a well are also disclosed.

Non-impulsive source actuation can include actuating a plurality of non-impulsive sources such that each one of a plurality of common midpoint (CMP) bins receives a desired aggregate signal exposure. Each one of the plurality of non-impulsive sources exposes each one of the plurality of CMP bins to a different part of the desired aggregate signal exposure at different times during the survey.

Processes and systems described herein are directed to performing marine surveys with a moving vibrational source that emits a continuous source wavefield into a body of water above a subterranean formation. The continuous source wavefield is formed from multiple sweeps in which each sweep is emitted from the moving vibrational source into the body of water with a randomized phase and/or with a randomized sweep duration. Reflections from the subterranean formation are continuously recorded in seismic data as the moving vibrational source travels above the subterranean formation. Processes and systems include iteratively deconvolving the source wavefield from the continuously recorded seismic data to obtain an earth response in the common receiver domain with little to no harmful effects from spatial aliasing and residual crosstalk noise. The earth response may be processed to generate an image of the subterranean formation.