The Woodford Shale like many other self-source unconventional rocks is evidently anisotropic. However, anisotropy (lamination/bedding) is not commonly included when defining “fracability”. Micro-resistivity logs, Core (Wyche-1) and thin section inspection illustrates that middle and lower Woodford Shale brittle intervals are characterized by more frequent and visible laminae, in comparison with the upper Woodford.
Thomsen’ coefficients e and ?, obtained from Ultra Pulse Velocities (UPV) analysis, were used to quantify anisotropy and to explore their potential effects on rock "fracability". The intervals that exhibit more laminae (anisotropy) are characterized by higher e and ? coefficients, which are also characterized by less Fracture toughness (K) and Tensile Strength (). A second order (~10-30 My), Sequence Stratigraphy model which was based on microfossils, geochemical and thin sections (Slatt et al., 2012), helps to explain the differences observed in laminations (anisotropy), between the upper Woodford Shale (HST) and the middle/lower (TST) organic-rich shale deposits.
This work illustrates that more laminae at middle Woodford brittle intervals creates more anisotropy planes of weakness, that may assist in reducing the effective minimum horizontal principal stress and they might affect clearly hydraulic stimulation.
Presentation Date: Wednesday, October 19, 2016
Start Time: 4:00:00 PM
Location: Lobby D/C
Presentation Type: POSTER
