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Brittleness Computation Without Density For Unconventional Resource Exploration And Development
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 9th Congress of the Balkan Geophysical Society, Nov 2017, Volume 2017, p.1 - 5
Abstract
Brittleness (B) and total organic carbon (TOC) estimations are required to identify and produce unconventional resources like gas and oil-bearing shales and tight sands with near zero or no permeability. B is the key property for horizontal well placement, and fracture development and sustainability assessments because fracturing required for production. Conventionally B is estimated from Young’s modulus (E) and Poisson’s ratio (□).
As E is a function of density (□), field wise B estimation from E (BE) after seismic inversion may be compromised because □ is the poorest estimate compared to acoustic impedance (AI) and shear impedance (SI). We introduced a simple quantitatively equivalent BE computation using E□. We also showed that it is preferable to use the average B estimation from E□ and μρ rather than the BE and □ brittleness (B_ν) average.
The examples of B and TOC estimation first from the well logs, then the rock parameters inverted from 3D land seismic data successfully mapped a brittle shale zone. Core analysis made at another well on the same target shale in this study showed that it is a source rock with API 42o, porosity > 4 %, Sw > 50 % and TOC > 2 %wt.