Exploration-Scale Lithology Indicator
Facies Finder provides easy-to-interpret attribute volumes for "at-a-glance" lithology identification. It uses an elastic inversion scheme which generates a relative Vp/Vs layer attribute to help discriminate between sand and shale. The inversion method is robust and requires no well calibration, making it suitable for field and basin studies at the exploration phase.
Facies Finder maximizes the value of seismic data early in the E&P cycle to highlight and de-risk potential prospects.
Facies Finder volume offshore West Africa. A stratigraphic slice through the volume is displayed where the well track intersects high-quality sands in a stacked channel complex, indicated by low Vp/Vs (green). Facies Finder was instrumental in identifying this deep prospect which was subsequently drilled and developed.
- Facies Finder attribute indicates clastic lithology
- Relative elastic inversion for qualitative Vp/Vs estimate
- Consistent attribute scaling for intuitive interpretation
- Robust inversion scheme requiring no well calibration
- May be extended to fluid discrimination when well control is available
- Intuitive attribute volumes for easy facies detection
- Exploration-phase prospect identification and de-risking
- Suitable for large-scale field and basin-wide studies
- Maximises value of seismic data early in the E&P cycle
West African Case History
Amplitude bright spots are often used as direct hydrocarbon indicators offshore West Africa. However, deeper sands have a similar acoustic impedance to the shales, which means that this class of reservoir will not produce an acoustic "bright spot" response. In addition, mud-dominated channels may also show bright amplitudes on stack data. Elastic impedance attributes are required to detect these deeper reservoirs and discriminate between mud- and sand-filled channels. The relative Vp/Vs volume from Facies Finder is ideal for this qualitative assessment of lithology.
The channel-sand complex identified by Facies Finder in this example was successfully drilled and hydrocarbons were found. Without the use of elastic impedance attributes at the exploration stage this prospect may have been overlooked.
On the full-offset stack (left), the deep reservoir sands marked by the arrow do not produce an acoustic impedance amplitude "bright spot", widely used as a direct hydrocarbon indicator in this region. The Facies Finder volume (right) clearly highlights the high-quality sands in the channel complex based on their very low relative Vp/Vs signature (green).
The track of the well drilled through this structure is shown.