Integrated seismic lithologic interpretation: The petrophysical basis. (Volumes I and II)

Reflection seismic methods are, and will continue to be, the key geophysical tool for imaging heterogeneities in the subsurface of the earth. Surprisingly, the amount of financial effort spent on quantitative lithologic interpretation is much less than that spent on acquisition and processing of the data. In spite of great advances in acquisition and processing, the primary product of conventional seismic work is still only the spatial pattern of reflectivity, which is essentially a measure of velocity variations. The seismic amplitude information is rich yet goes mostly unused. I attribute this to a general lack of understanding or knowledge of petrophysics, and I believe that petrophysics appears to have been the "weak link in quantitative seismic lithologic interpretation".; The above statement is the more surprising, when considering the following: (1) the pressing need for lithologic inversion as opposed to elastic velocity inversion, since explorationists and "exploitationists-productionists" are ultimately interested in rock properties, and not in velocities or impedance contrasts. (2) the necessity for a quantitative methodology to integrate different data types and scales, and to use them for the best parameterization possible in theoretical models of wave propagation.; The complexity of interaction between the numerous parameters affecting seismic waves dictates that any quantitative extraction of rock properties from seismic be model-based. Having recognized this fact, I first concentrate on understanding the wave equation and on details of wave propagation through complex media. This leads to the identification of the key parameters affecting seismic reflection signatures: elastic velocities, density, anisotropy, and anelasticity.; Second, I devise a state-of-the-art methodology to estimate these crucial parameters from diverse sets of different rock properties. An integrated deterministic modeling scheme is proposed, whereby detailed petrophysical properties from the microscale are used in the determination of smoothed long wavelength equivalent transverse isotropic media at the seismic macroscale. This is integration of scales. Integration reduces the non-uniqueness problem and allows for the combined benefits of borehole information which is very accurate in the vertical direction and of seismic which has a large scale lateral resolution. This is integration of techniques and disciplines.; The two previous theoretical efforts are then put to the test in the study of a loosely consolidated reservoir from the North Sea. Using both seismic amplitudes and velocities with emphasis on AVO analysis, I show that petrophysics can serve as the linking bridge between integrated reservoir characterization and the actual geology of the subsurface. I then show that the use of model-based seismic interpretation combined with sound petrophysical principles can lead to better reservoir management.