Chaveste, Alvaro1, Bruce Hill2, Darrel Corcoran2
(1) Traceseis, Houston, TX
(2) Core Laboratories, Houston, TX
ABSTRACT: Rock Properties - The Link Between Wireline and Pre-Stack Seismic Data
Amplitude Variation with Offset (AVO) of properly processed pre-stack seismic data is dependent upon angle of incidence of seismic waves to an interface as well as to the relative changes of the physical properties (P- and S-wave velocities and densities) across the interface. The information that can be extracted from pre-stack seismic is then, at best, related to these physical properties and the estimation, from seismic data, of petrophysical properties such as porosity, lithology or pore fluids has to be done through a link, provided by rock physics, between attributes related to velocities and density and the petrophysical property being evaluated.
The methodology presented links, at well log resolution, P- and S-wave velocities (VP and VS) and densities () to porosity (), shale percent (Vsh) and water saturation (Sw) through rock properties that can also be obtained from seismic data. The fact that the same properties are computed from both, log and seismic, allows for rigorous parameterization and QC of the processes applied to the seismic data at different stages of the processing sequence. Additionally, well log reconstruction allows for accurate environmental corrections (namely invasion) as well as modeling, at well log resolution, of different reservoir conditions; thus allowing for sensitivity and ambiguity analyses. This same evaluation can be done at seismic resolution through the generation of pre-stack synthetic gathers.
The different stages of the methodology are illustrated with both real and modeled data. In the end, the knowledge gained through Well Log Reconstruction and modeling at both log and seismic scales is used in the identification of potential reservoirs through the estimation of 3D pre-stack seismic data.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004