Seismic lithology analysis using acoustic impedance vs. Poisson Ratio crossplots
- Geophysical Development Corp., Houston, TX (United States)
Case studies demonstrate predictions of lithology, porosity and pore fluid variations for relatively high acoustic impedance ([rho]V) gas-sands. We utilize amplitude versus offset analysis (AVO) along with crossplotting well log and seismic parameters. These approaches extend application of AVO to non-bright spot sands where gas-sands [rho]V equals or even exceeds shale [rho]V. It also utilizes Poisson Ratio estimates ([sigma]) from Poisson Reflectivity analysis to overcome limitations in stack seismic inversion. One study investigates a Gulf of Mexico Miocene gas sand. The 110 ft target zone at [approximately]14000 ft consists of a high velocity, and low-density with respect to the encasing shale. Using a color crossplot display, different colors portray gas-sands, wet-sands and high [rho]V shale/shale boundaries. Location of the sand colors appears consistent with wells and with sand deposition along growth faults. Another study targets channel sands interfinger with debris-flow facies to reach a thickness of 160 ft, with net pay of 69 ft. Maximum porosity is 22% with pay reservoir quality to 9%. The channel facies provide excellent reservoir quality, while intergranular detrital clay in the debris-flow facies reduces it. A [rho]V - [sigma] inversion discriminates these facies. Near the productive wells, [sigma] shows a significant drop from the background. Also, crossplot displays reveal that these sands occur within a canyon-like feature. With this definition of geometry and seismic facies, we have the potential to predict well performance in areas where interfingered sands are below seismic resolution.
- OSTI ID:
- 6860169
- Report Number(s):
- CONF-960527-; CODEN: AABUD2
- Journal Information:
- AAPG Bulletin, Vol. 5; Conference: Annual convention of the American Association of Petroleum Geologists, Inc. and the Society for Sedimentary Geology: global exploration and geotechnology, San Diego, CA (United States), 19-22 May 1996; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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