Amplitude versus offset

Andreassen (1995) used the amplitude versus offset (AVO) technique to determine the phases at the BSR interface. The classical AVO technique, as stated by Ostrander (1984), measures the angle-dependent P-wave ratio amplitude (reflected to incident). Andreassen and coworkers determined that usually gas is just below the hydrate layer. 

Monitoring by 3D repeatable seismic measures [3], also commonly named 4D seismic, is still, more or less, at the research stage (even in E P field) but early tests seem promising. This system is based on techniques such as the use of seismic sensors placed at regular intervals on the surface or in wells (permanently) [4]. Advanced multi covering seismic such as AVO (Amplitude Versus Offset) can help in better investigating petrophysical properties of reservoirs. 

Amplitude versus offset (AVO) techniques use the partititMiing of elastic wave energy at a reflecting boundary for extractirMi of information about fluid and lithology. This is controlled by the elastic properties of the two materials and the angle of the incident wave. It results in an offset-dependent reflectivity (amplitude), observed as Amplitode versus offset . 

Figure 9.6 Log modulus of survival amplitude for = 0.5 versus t in dimensionless units, in Longhi s discrete model. Solid lines exact analytical solution dashed line approximation of Eq. (100) (upper curve) and Eq. (99) (lower curve, offset by two decades).

The same setup is used in impedance spectroscopy. Here, electrode impedance composed of amplitude and phase is measured by putting a sine voltage with varying frequency (V/jy in Fig. 1.6) on the electrode (a DC offset of Vr will exist at Vw) and measuring the resulting current amplitude and phase shift over the frequency. The impedance spectrum of the electrode under test, i.e. Z-w rk versus frequency of Vi, is determined. An electrode model can be extracted from the resulting impedance data. It is usually composed of the prevalent linear components in electrical engineering like resistor and capacitor and components which are defined for the especial use in electrochemistry. One of these elements is introduced in Chap. 8, namely the constant phase element. 

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