Advanced geohazards assessment in shallow water through the estimation of primaries by sparse inversion

Toxopeus, Gerrit; Borselen, Roald van; Baardman, Rolf; Auer, L. M.; Ødegaard, E.

doi:10.1190/1.3627932

Cited by 5 publications

(2 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(), Toxopeus et al . (), and Buckley and Cottee (in press); however, Games () considered that, for very shallow targets, exploration 3D data may be unusable for AVO purposes. Extended AVO methods such as fluid‐factor, stack projection, EI, and EEI, for the purposes of MEG data interpretation, remain comparatively unreported.…”

Section: Petrophysical Methodologies and Data Sourcesmentioning

confidence: 99%

“…AVO methods of interpreting for shallow gas in top-hole drilling hazard studies are discussed in Townsend and Armstrong (1990), Lee et al (2010), Toxopeus et al (2011), and Buckley and Cottee (in press); however, Games (2012) value of 0.567 (Simm and Bacon 2014), a time-analysis-intervalto-wavelet-length ratio of 6.4, and an NMSE of 0.029. The estimated wavelet has a phase shift of 26° from the 3D seismic with a time shift of -4 ms.…”

Section: Case Study No 1-synthetic Well-tie North Seamentioning

confidence: 99%

See 1 more Smart Citation

A petrophysical approach to the investigation of shallow marine geology

Buckley

Cottee

2017

Near Surface Geophysics

View full text Add to dashboard Cite

Interpretations of commercial marine shallow seismic data are generally limited to a prognosis of lithologies based on sparse ground truth data and regional stratigraphic models and a probability assessment of encountering perceived geohazards. However, an approach based on analyses of available petrophysical data can provide a more robust assessment of shallow marine lithologies and a more confident interpretation of shallow gas and overpressured formations. Generation of well‐ and borehole‐log acoustic impedance curves provides the starting point for these investigations and, although not all of the requisite data may be present in shallow section wireline suites, the Faust and Gardner equations, and other empirically derived relationships, can supply acceptable mathematical approximations. Impedance inversions of reflection seismic data facilitate more confident interpretations of lithological units, especially when combined with additional datasets such as gamma‐ray, resistivity, porosity, and S‐wave sonic, as elastic and extended elastic inversions. Anomalous seismic events interpreted to represent a probability of encountering shallow gas using traditional interpretation methods may be further investigated using amplitude‐versus‐offset cross‐plotting techniques, including fluid factor calculations, and the potential for overpressured gas accumulations or flow sands may be estimated from velocity‐derived pore pressure calculations. Geological and synthetic seismic modelling exercises provide the opportunity to test petrophysical interpretations in the absence of ground truth control data.

show abstract

Section: Petrophysical Methodologies and Data Sourcesmentioning

confidence: 99%

Section: Case Study No 1-synthetic Well-tie North Seamentioning

confidence: 99%

A petrophysical approach to the investigation of shallow marine geology

Buckley

Cottee

2017

Near Surface Geophysics

View full text Add to dashboard Cite

show abstract

Frequency-dependent Amplitude Versus Offset analysis of a Cenozoic mass-transport deposit on the Namibian slope

Buckley¹,

Carnell²,

Al-Maskari³

et al. 2022

View full text Add to dashboard Cite

A partially tuned, ‘soft’ seismic reflection, overlying a regional limestone marker on the west African slope, is shown to represent a sequence, up to 30m thick, within which various individual stratigraphic units are identified, some of which display characteristics of a mass-transport deposit. The seismic reflection is described in terms of its two-way time structure, reflection amplitude pattern, complex seismic attributes and AVO response. Frequency dependent aspects of the AVO response, resulting from velocity attenuation and dispersion of seismic signals, are shown to indicate variations in pore-fluid gas concentration. These are exploited to assess lithological, petrophysical and pore-fluid characteristics of the various sub-units within the sequence. A relative acoustic impedance inversion of the seismic data is combined with a low-frequency model, constructed from acoustic velocity data, to approximate absolute acoustic impedance characteristics of the sequence and to model behaviour of the various sub-units across the area. This pseudo-absolute impedance data is combined with evidence from AVO analysis, to construct a 2D model of the mass-transport deposit (MTD) unit and to generate a synthetic seismic record, which confirms the interpretation of stratigraphic, petrophysical and lithological properties of the MTD complex.

show abstract

Robust estimation of primaries by sparse inversion via one-norm minimization

Lin

Herrmann

2013

GEOPHYSICS

View full text Add to dashboard Cite

A recently proposed method called estimation of primaries by sparse inversion (EPSI) avoids the need for adaptive subtraction of approximate multiple predictions by directly inverting for the multiple-free subsurface impulse response as a collection of band-limited spikes. Although it can be shown that the correct primary impulse response is obtained through the sparsest possible solution, the original EPSI algorithm was not designed to take advantage of this result, and instead it relies on a multitude of inversion parameters, such as the level of sparsity per gradient update. We proposed and tested a new algorithm, named robust EPSI, in which we make obtaining the sparsest solution an explicit goal. Our approach remains a gradient-based approach like the original algorithm, but it is derived from a new biconvex optimization framework based on an extended basis-pursuit denoising formulation. Furthermore, because it is based on a general framework, robust EPSI can recover the impulse response in transform domains, such as sparsifying curvelet-based representations, without changing the underlying algorithm. We discovered that the sparsity-minimizing objective of our formulation enabled it to operate successfully on a variety of synthetic and field marine data sets without excessive tweaking of inversion parameters. We also found that recovering the solution in alternate sparsity domains can significantly improve the quality of the directly estimated primaries, especially for weaker late-arrival events. In addition, we found that robust EPSI produces a more artifact-free impulse response compared to the original algorithm.

show abstract

Advanced geohazards assessment in shallow water through the estimation of primaries by sparse inversion

Cited by 5 publications

References 7 publications

A petrophysical approach to the investigation of shallow marine geology

A petrophysical approach to the investigation of shallow marine geology

Frequency-dependent Amplitude Versus Offset analysis of a Cenozoic mass-transport deposit on the Namibian slope

Robust estimation of primaries by sparse inversion via one-norm minimization

Contact Info

Product

Resources

About