Below is a typical sequence in EcoStim's "sweet spot" map-generation process:
- Receipt of 3D seismic and well production information
- Wavelet extraction and creation of a deterministic inversion
- Analysis of sonic, density and impedance logs for appropriate distributions
- Generation of multiple (~100) realizations over the target zones(s)
- Presentation of results
The noise-attenuated and sharpened output is used as the input volume for all subsequent attribute and inversion work. The noise reduction capability is such that we can whiten the input data to an arbitrarily high-side cutoff, usually 80-120 Hz, and selectively attenuate the noise enhanced in the whitening process while preserving the additional signal to produce data with, on the average, a 20 Hz increase in bandwidth and less noise than the input data.
Note that acoustic inversion of any kind requires that variations in velocity and density relate to prospectivity. Stochastic inversion requires sufficient well control and is performed only for narrow target zones. Such zones may contain more than one producing interval, but producing intervals widely spaced in seismic time must be treated separately.
Acoustic Inversion Example
Tie Line Flattened on Top (Eagle Ford Shale)
Acoustic-impedance inversion of two wells in the Eagle Ford Shale. Well A was drilled in the deeper high-impedance zone and Well B rose from that zone to the lower-impedance section. Well A has high EUR due to its location in the more easily fractured brittle zone.