Geoscience Reference
In-Depth Information
Porosity vs Dry Rock Poisson Ratio
0.5
0.45
0.4
0.35
σ
d
0.3
0.25
0.2
0.15
0.1
0.05
0
0
0.1
0.2
0.3
0.4
Porosity
Fig. 5.28
Dry rock Poisson ratio versus porosity for some real sandstone examples.
amplitude change, or a flat event that may be a DHI, the following checklist may be
useful.
Are there analogues to show the effects of lithology/ fluid fill on seismic amplitude?
Are there enough good quality well data to carry out modelling studies?
Are the well data from a closely analogous case (e.g. sedimentary environment)?
Is well data quality good enough (e.g. correction of logs for invasion effects)?
Is the amplitude change predicted from the model big enough to be detectable?
Has modelling addressed enough scenarios, including non-pay cases?
Is the effect of change in fluid greater than the effect of likely porosity changes?
Is there a good well tie to establish seismic phase and polarity?
Alternatively, can phase and polarity be deduced from known isolated reflectors?
Are horizon picks uncertain?
Has seismic been processed to preserve amplitudes?
In particular, has short-gate (
1000 ms) AGC been avoided?
Does the seismic have good signal/noise and imaging?
Are multiples a problem?
Do overburden complications affect seismic propagation?
Are the pre-stack data good enough to use AVO methods?
If there is a flat spot, does it have the right polarity?
Is the flat spot discordant with bedding-plane reflectors?
Is there a bright spot/dim spot?
Is the degree of brightening/dimming as expected for a fluid effect?
Are several features concordant in indicating hydrocarbons?
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