Integrated reflection and refraction processing of an ultra-shallow seismic survey

Meulenbroek, Alan

doi:10.1071/aseg2015ab032

Cited by 2 publications

(8 citation statements)

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“…In general, the shallower event (at ∼ 0.1 s) on the dispersion-velocity stack produces a simpler structure (more-pronounced mostly-singular event with less splitting). This is likely to correspond to the base of weathering and compares more favourably with ultra-shallow P-wave reflection results previously acquired along the line (Meulenbroek, 2015).…”

Section: Application To S-wave Reflection Processingsupporting

confidence: 56%

“…Structural features on the section are supported by a previously performed P-wave refraction analysis (Meulenbroek, 2015), as will be considered in more detail below.…”

Section: Mode Selection and Inversionmentioning

confidence: 65%

“…This is more clearly defined on the S-wave data with distinct lateral variation around Station 3200. This may correlate to some of the structures suggested by the P-wave reflection data (Meulenbroek, 2015).…”

Section: Structural Comparison With Refraction Tomographymentioning

confidence: 95%

“…Of particular interest was an ultra-high resolution vertical-component (1C) P-wave survey (Trial 1). The processing of this survey included P-wave refraction tomography (Meulenbroek, 2015). Table 8.1 compares some of the parameters used in the 1C and 3C surveys.…”

Section: Structural Comparison With Refraction Tomographymentioning

confidence: 99%

“…This was mounted in a frame and coupled using a vehicle ( Figure 8.1). A manually-operated vertical impactor (Bigfoot, see Meulenbroek, 2015) was used to generate the P-wave energy (Figure 8.2). This was also used in an inclined configuration to generate S waves where vehicle access was restricted.…”

Section: Introductionmentioning

confidence: 99%

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Resolution enhancement in shallow 3D-PS seismic reflection

Strong¹

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This thesis aims to advance methodology for acquiring and processing 3D multicomponent seismic data for shallow (< 300 m) exploration targets. The primary focus is to improve seismic resolution, and hence geological interpretation, for coal-scale targets.The coal industry is a significant contributor to the energy security and economy of Australia and the world. Conventional P-wave seismic methods are widely used in this industry, providing economic, safety and environmental benefits. There is potential for expanding these benefits by including multicomponent procedures. In this thesis, the primary focus is on converted-wave (PS) reflection, which is a logical extension to the standard approach. This has theoretical potential to provide extra geological information. It has also been proposed that there may be resolution advantages for shallower targets such as coal.A valuable starting point for understanding resolution in shallow P and PS reflection is via visco-elastic finite-difference simulation. This provides a useful indication of the reflection response of different targets, and can include the influence of different processing flows. For typical coal-scale environments, modelling with reasonable anelasticity assumptions suggests that PS resolution is unlikely to be superior to P resolution, even with idealised acquisition and processing. In real-world situations, achieving good PS resolution may be even more challenging. There are a number of factors across the acquisition and processing flow which incrementally influence resolution.Survey design is intrinsically more complex for PS surveys than for P, primarily because of ray-path asymmetry. In addition, phase and amplitude effects require careful analysis, and finite-difference modelling provides a useful tool. Such modelling suggests that for shallow surveys in particular, it may be possible to incorporate longer relative offsets, compared to the petroleum scale. An examination of bin fold, and offset/azimuth distribution, suggests that the natural bin size of a PS survey is mostly dependent on the receiver spacing, and is generally larger than for P waves. This favours the use of higher receiver densities for multicomponent surveys. These observations can be more important at the shallow scale, again because of greater ray-path asymmetry and potentially higher V P /V S value.One of the most critical steps in the shallow PS processing sequence is correcting for the S-wave receiver statics. Three relatively conventional approaches have been evaluated. A surface-consistent inversion approach has been shown to fail for shallow targets, or in the presence of strong noise. For our 3D data set, PPS refraction analysis provided the preferred solution. In other cases where PPS refractions are poorly defined, our robust statistical approach may be useful for determining short-wavelength statics, although additional long-wavelength control would then be needed.ii In exploration seismology, surface waves are commonly considered to be noise. However, the d...

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Section: Application To S-wave Reflection Processingsupporting

confidence: 56%

“…Structural features on the section are supported by a previously performed P-wave refraction analysis (Meulenbroek, 2015), as will be considered in more detail below.…”

Section: Mode Selection and Inversionmentioning

confidence: 65%

Section: Structural Comparison With Refraction Tomographymentioning

confidence: 95%

Section: Structural Comparison With Refraction Tomographymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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