Deghosting by echo-deblending

Because of the strong sea surface reflectivity, a marine source generates both a direct wavefield and a ghost wavefield. This corresponds to a blended source array, the blending process being natural. Consequently, deghosting becomes deblending ('echo-deblending'). We discuss source deghosting by an iterative deblending algorithm that properly...

Using Ghost Reflections Rather than Removing Them

In marine acquisition both a direct wavefield and a ghost wavefield are produced as well as recorded. Hence, the seismic data can be considered to be a natural blend of four wavefields related to the real sources, ghost sources, real detectors and ghost detectors respectively. We consider deghosting to be deblending ('echo-deblending'), leading...

Broadband seismic by means of dispersed source arrays

Seismic sources deployed during a particular survey are historically chosen to be equal. However, from a physical point of view the constraint of using only identical source units is not required. We suggest to abandon this constraint and to replace, or reinforce, traditional broadband sources with narrower-band devices, together representing a...

Benefits of blended acquisition with dispersed source arrays (DSA)

In blended data acquisition, the recorded wave field is incoherent. Nevertheless blended source units in the arrays are historically chosen to be equal. We propose to abandon this constraint. This allows us to suggest the exploitation of inhomogeneous blended sources, together representing a Dispersed Source Array (DSA). Each source unit...

Toward the limits of deblending

If we bring sources closer together, they start to `sense' the nearness of each other and their physical behaviour will change. If the separation becomes smaller than half a wavelength, they start to act as one source with new properties (temporal bandwidth, directivity). This fusion process is very complex and nonlinear. To find out whether...

Marine survey design and analysis using all multiples

Despite a tremendous leap in efficiency and wave field sampling over the last two decades, it is sometimes still difficult to achieve adequate coverage and resolution with marine streamer acquisition. It is therefore necessary to carefully study the acquisition geometry, especially with respect to resolution and image quality in the cross-line...

The impact of surface-wave separation on seismic survey design

3-D seismic survey design provides an acquisition geometry for obtaining seismic data that enable imaging and amplitude-versus-offset applications of target reflectors with sufficient quality under given economical and operational constraints. However, in land or shallow water environments, surface waves are often dominant and will lower the...

3-D acquisition geometry analysis: Incorporating information from multiples

Recent advances in survey design have led to conventional common-midpoint-based analysis being replaced by the subsurface-based seismic acquisition analysis and design, with the emphasis on advance techniques of illumination analysis. Amongst them are wave-equation-based seismic illumination analyses such as the so-called focal beam method. The...

Dispersive multi-modal mud-roll estimation and removal using feedback-loop approach

In a shallow water environment, mud-rolls are often dominant and appear as a prevailing coherent linear noise in OBC seismic data. Their complex properties make the noise removal notably challenging in seismic processing. To address the challenges, we propose a method of dispersive multi-modal mud-roll estimation and removal, using the feedback...

Separation of Blended Data by Sparse Inversion Utilizing Surface-related Multiples

Blended surveys have recently appeared in production environments. This underlines the need for processing tools that will either process the recorded data directly or perform the separation into single source data (deblending). An inversion technique for the separation of such data is described here. The problem parameterization utilises the...

Blended acquisition with optimized dispersed source arrays

Until now, blended source arrays are configured with closely spaced source units, such as broadband airgun arrays (marine) and broadband vibrator arrays (land). In the latter case the source units are equal. We refer to this concept as homogeneous blending. In this paper the blending concept is extended to inhomogeneous blending, meaning that a...

Fast multifrequency focal beam analysis for 3D seismic acquisition geometry

A method for the efficient computation of multifrequency focal beams for 3D seismic acquisition geometry analysis has been developed. By computing them for all the frequency components of seismic data, single-frequency focal beams can be extended to multifrequency focal beams. However, this straightforward method involves considerable computer...

Multiscattering illumination in blended acquisition

In traditional seismic surveys, the firing time between shots is such that the shot records do not interfere in time. However, in the concept of blended acquisition, the records do overlap, allowing denser source sampling and wider azimuths in an economic way. A denser shot sampling and wider azimuths make that each subsurface gridpoint is...

Acquisition design for fluid front monitoring: The Schoonebeek field

The subsurface image obtained from seismic data can be biased by the acquisition geometry: it contains an acquisition footprint, which can obstruct the subsurface characterization. So the acquisition geometry for a seismic experiment should be designed in such a way that it allows high-quality images and fulfills the criteria for the reservoir...

Separation of blended data by iterative estimation and subtraction of blending interference noise

Seismic acquisition is a trade-off between economy and quality. In conventional acquisition the time intervals between successive records are large enough to avoid interference in time. To obtain an efficient survey, the spatial source sampling is therefore often (too) large. However, in blending, or simultaneous acquisition, temporal overlap...