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Consequently, four response cases are possible, as shown in [[:file:amplitude-versus-offset-avo-analysis_fig1.png|Figure 1]]. Two of these cases—(a) and (c)—represent constructive summation of the two terms, yielding a large AVO response. The other two cases—(b) and (d)—are destructive, and the total AVO response is small. A third case consisting of little shear response and strong acoustic response may produce high AVO and may not be associated with a Poisson's ratio contrast.

Consequently, four response cases are possible, as shown in [[:file:amplitude-versus-offset-avo-analysis_fig1.png|Figure 1]]. Two of these cases—(a) and (c)—represent constructive summation of the two terms, yielding a large AVO response. The other two cases—(b) and (d)—are destructive, and the total AVO response is small. A third case consisting of little shear response and strong acoustic response may produce high AVO and may not be associated with a Poisson's ratio contrast.

In addition to the acoustic and shear components of the AVO response, there are the effects of AVO tuning from thin beds. In contrast to normal incidence tuning, AVO tuning varies with offset and gives rise to amplitude and waveform changes concurrently.

In addition to the acoustic and shear components of the AVO response, there are the effects of AVO [[tuning]] from thin beds. In contrast to [[normal incidence]] tuning, AVO tuning varies with offset and gives rise to amplitude and waveform changes concurrently.

Feasibility modeling requires the following: (1) a depth-velocity model, (2) density and velocity trend curves, (3) [[porosity]] ranges, (4) fluid content variation, (5) Poisson's ratio trend curves, and (6) a geological description of potential reservoir and encompassing environments. [[:file:amplitude-versus-offset-avo-analysis_fig2.png|Figures 2]] and [[:file:amplitude-versus-offset-avo-analysis_fig3.png|3]] show model examples consisting of two fluid types. [[:file:amplitude-versus-offset-avo-analysis_fig2.png|Figure 2]] is a brine sand model, and [[:file:amplitude-versus-offset-avo-analysis_fig3.png|Figure 3]] is a gas sand model. The sensitivity of the seismic expression can now be studied by changing model parameters. If the model studies indicate measurable AVO responses, then AVO processing and interpretation techniques can be undertaken at an early stage in the exploration effort.

Feasibility modeling requires the following: (1) a depth-[[velocity]] model, (2) density and velocity trend curves, (3) [[porosity]] ranges, (4) fluid content variation, (5) Poisson's ratio trend curves, and (6) a geological description of potential reservoir and encompassing environments. [[:file:amplitude-versus-offset-avo-analysis_fig2.png|Figures 2]] and [[:file:amplitude-versus-offset-avo-analysis_fig3.png|3]] show model examples consisting of two fluid types. [[:file:amplitude-versus-offset-avo-analysis_fig2.png|Figure 2]] is a brine sand model, and [[:file:amplitude-versus-offset-avo-analysis_fig3.png|Figure 3]] is a gas sand model. The sensitivity of the seismic expression can now be studied by changing model parameters. If the model studies indicate measurable AVO responses, then AVO processing and interpretation techniques can be undertaken at an early stage in the exploration effort.

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