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Seismic Porosity Prediction in Chalks - Pitfalls and Potentials
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 73rd EAGE Conference and Exhibition incorporating SPE EUROPEC 2011, May 2011, cp-238-00614
- ISBN: 978-90-73834-12-5
Abstract
In this paper the effect of several factors influencing the porosity determination from seismic inversion as well as their interplay have been discussed. The main findings may be summarized in three points: 1) Porosity cannot be uniquely determined from acoustic impedance without having information about what fluid saturates the pore space. As the AI is decreasing, the range of the possible porosity values is increasing in function of effective fluid density. 2) Upscaled (Backus averaged) and the well data show the same (quadratic) trend, i.e. the scale does not affect the relationship between AI and porosity. However, high and low porosity tails are lost as a consequence of averaging a finite thickness into a single point, thus a high resolution information is lost. 3) Upscaled well log data with noise is showing a different trend in high porosity part when compared with quadratic trend from well log data and upscaled well log data.